Search Results: "andy"

10 January 2026

Matthias Geiger: Building a propagation box for oyster mushrooms

Inspiration In November I watched a short documentary about a guy who grew pearl oyster mushrooms in his backyard. They used pallet boxes (half of a europallet, 60x80x20 cm) as box to keep the substrate the mycelium feeds on in. Since I really enjoy (foraged) mushrooms and had the raw materials lying around, I opted to build it myself. This also had the benefit of using what was available and not just consuming, i.e. buying a pallet box. Preparing the raw materials I had 4.5 m x ~ 25 cm wooden spruce planks at home. My plan was to cut those into 2 m segments, then trim the edges down to 20 cm and then cut them into handy pieces, following the dimension of half a pallet box. This is what they looked after cutting them with an electric chainsaw to around 2 m: raw_planks You can see that the edges are still not straight, because that's how they came out of the sawmill. Once that was done I visited a family member that had a crosscut saw, a table saw and a band saw; all that I would need. First we trimmed the edges of the 2m planks with the table saw so they were somewhat straight; then they were flipped and the other edge was cut straight, and their width cut down to 20 cm. After moving them over to the crosscut saw dividing them into two 60 cm and one 80 cm was fairly easy. When cutting the 2m planks from the 4m ones I calculated with extra offcuts, so I got little waste overall and could use the whole length to get my desired board. This is what the cut pieces looked like: cut_planks Assembly I packed up my planks, now nicely cut to size, and I went to a hardware shop and bought hinges and screws. Assembly was fairly easy and fast: screw a hinge to a corner, hold the other plank onto the hinge so that the corners of both boards touch, and affix the hinge. plank_with_hinge corner_with_hinge When this was done, the frame looked like this: finished_frame As last step I drilled 10mm holes more or less random in the middle of the box. This is where the mushrooms will grow out of later and can be harvested. box_with_holes Closing thoughts This was a fun project I finished in a day. The hinges have the benefit that they allow the box to be folded up lenght-wise: folded This allows for convenient storage. Since it's too cold outside right now, cultivation will have to wait until spring. This also just needs mycelium one can just buy, and some material fungus digests. They can also be fed coffee grounds, and harvest of the fruit body is possible circa every two weeks.

31 December 2025

kpcyrd: 2025 wrapped

Same as last year, this is a summary of what I ve been up to throughout the year. See also the recap/retrospection published by my friends (antiz, jvoisin, orhun). Thanks to everybody who has been part of my human experience, past or present. Especially those who ve been closest.

25 December 2025

Russ Allbery: Review: Machine

Review: Machine, by Elizabeth Bear
Series: White Space #2
Publisher: Saga Press
Copyright: October 2020
ISBN: 1-5344-0303-5
Format: Kindle
Pages: 485
Machine is a far-future space opera. It is a loose sequel to Ancestral Night, but you do not have to remember the first book to enjoy this book and they have only a couple of secondary characters in common. There are passing spoilers for Ancestral Night in the story, though, if you care. Dr. Brookllyn Jens is a rescue paramedic on Synarche Medical Vessel I Race To Seek the Living. That means she goes into dangerous situations to get you out of them, patches you up enough to not die, and brings you to doctors who can do the slower and more time-consuming work. She was previously a cop (well, Judiciary, which in this universe is mostly the same thing) and then found that medicine, and specifically the flagship Synarche hospital Core General, was the institution in all the universe that she believed in the most. As Machine opens, Jens is boarding the Big Rock Candy Mountain, a generation ship launched from Earth during the bad era before right-minding and joining the Synarche, back when it looked like humanity on Earth wouldn't survive. Big Rock Candy Mountain was discovered by accident in the wrong place, going faster than it was supposed to be going and not responding to hails. The Synarche ship that first discovered and docked with it is also mysteriously silent. It's the job of Jens and her colleagues to get on board, see if anyone is still alive, and rescue them if possible. What they find is a corpse and a disturbingly servile early AI guarding a whole lot of people frozen in primitive cryobeds, along with odd artificial machinery that seems to be controlled by the AI. Or possibly controlling the AI. Jens assumes her job will be complete once she gets the cryobeds and the AI back to Core General where both the humans and the AI can be treated by appropriate doctors. Jens is very wrong. Machine is Elizabeth Bear's version of a James White Sector General novel. If one reads this book without any prior knowledge, the way that I did, you may not realize this until the characters make it to Core General, but then it becomes obvious to anyone who has read White's series. Most of the standard Sector General elements are here: A vast space station with rings at different gravity levels and atmospheres, a baffling array of species, and the ability to load other people's personalities into your head to treat other species at the cost of discomfort and body dysmorphia. There's a gruff supervisor, a fragile alien doctor, and a whole lot of idealistic and well-meaning people working around complex interspecies differences. Sadly, Bear does drop White's entertainingly oversimplified species classification codes; this is the correct call for suspension of disbelief, but I kind of missed them. I thoroughly enjoy the idea of the Sector General series, so I was delighted by an updated version that drops the sexism and the doctor/nurse hierarchy and adds AIs, doctors for AIs, and a more complicated political structure. The hospital is even run by a sentient tree, which is an inspired choice. Bear, of course, doesn't settle for a relatively simple James White problem-solving plot. There are interlocking, layered problems here, medical and political, immediate and structural, that unwind in ways that I found satisfyingly twisty. As with Ancestral Night, Bear has some complex points to make about morality. I think that aspect of the story was a bit less convincing than Ancestral Night, in part because some of the characters use rather bizarre tactics (although I will grant they are the sort of bizarre tactics that I could imagine would be used by well-meaning people using who didn't think through all of the possible consequences). I enjoyed the ethical dilemmas here, but they didn't grab me the way that Ancestral Night did. The setting, though, is even better: An interspecies hospital was a brilliant setting when James White used it, and it continues to be a brilliant setting in Bear's hands. It's also worth mentioning that Jens has a chronic inflammatory disease and uses an exoskeleton for mobility, and (as much as I can judge while not being disabled myself) everything about this aspect of the character was excellent. It's rare to see characters with meaningful disabilities in far-future science fiction. When present at all, they're usually treated like Geordi's sight: something little different than the differential abilities of the various aliens, or even a backdoor advantage. Jens has a true, meaningful disability that she has to manage and that causes a constant cognitive drain, and the treatment of her assistive device is complex and nuanced in a way that I found thoughtful and satisfying. The one structural complaint that I will make is that Jens is an astonishingly talkative first-person protagonist, particularly for an Elizabeth Bear novel. This is still better than being inscrutable, but she is prone to such extended philosophical digressions or infodumps in the middle of a scene that I found myself wishing she'd get on with it already in a few places. This provides good characterization, in the sense that the reader certainly gets inside Jens's head, but I think Bear didn't get the balance quite right. That complaint aside, this was very fun, and I am certainly going to keep reading this series. Recommended, particularly if you like James White, or want to see why other people do.
The most important thing in the universe is not, it turns out, a single, objective truth. It's not a hospital whose ideals you love, that treats all comers. It's not a lover; it's not a job. It's not friends and teammates. It's not even a child that rarely writes me back, and to be honest I probably earned that. I could have been there for her. I didn't know how to be there for anybody, though. Not even for me. The most important thing in the universe, it turns out, is a complex of subjective and individual approximations. Of tries and fails. Of ideals, and things we do to try to get close to those ideals. It's who we are when nobody is looking.
Followed by The Folded Sky. Rating: 8 out of 10

19 December 2025

Otto Kek l inen: Backtesting trailing stop-loss strategies with Python and market data

Featured image of post Backtesting trailing stop-loss strategies with Python and market dataIn January 2024 I wrote about the insanity of the Magnificent Seven dominating the MSCI World Index, and I wondered how long the number can continue to go up? It has continued to surge upward at an accelerating pace, which makes me worry that a crash is likely closer. As a software professional, I decided to analyze whether using stop-loss orders could reliably automate avoiding deep drawdowns. As everyone with some savings in the stock market (hopefully) knows, the stock market eventually experiences crashes. It is just a matter of when and how deep the crash will be. Staying on the sidelines for years is not a good investment strategy, as inflation will erode the value of your savings. Assuming the current true inflation rate is around 7%, a restaurant dinner that costs 20 euros today will cost 24.50 euros in three years. Savings of 1000 euros today would drop in purchasing power from 50 dinners to only 40 dinners in three years. Hence, if you intend to retain the value of your hard-earned savings, they need to be invested in something that grows in value. Most people try to beat inflation by buying shares in stable companies, directly or via broad market ETFs. These historically grow faster than inflation during normal years, but likely drop in value during recessions.

What is a trailing stop-loss order? What if you could buy stocks to benefit from their value increasing without having to worry about a potential crash? All modern online stock brokers have a feature called stop-loss, where you can enter a price at which your stocks automatically get sold if they drop down to that price. A trailing stop-loss order is similar, but instead of a fixed price, you enter a margin (e.g. 10%). If the stock price rises, the stop-loss price will trail upwards by that margin. For example, if you buy a share at 100 euros and it has risen to 110 euros, you can set a 10% trailing stop-loss order which automatically sells it if the price drops 10% from the peak of 110 euros, at 99 euros. Thus, no matter what happens, you only lost 1 euro. And if the stock price continues to rise to 150 euros, the trailing stop-loss would automatically readjust to 150 euros minus 10%, which is 135 euros (150-15=135). If the price dropped to 135 euros, you would lock in a gain of 35 euros, which is not the peak price of 150 euros, but still better than whatever the price fell down to as a result of a large crash. In the simple case above, it obviously makes sense in theory, but it might not make sense in practice. Prices constantly oscillate, so you don t want a margin that is too small, otherwise you exit too early. Conversely, having a large margin may result in too large a drawdown before exiting. If markets crash rapidly, it might be that nobody buys your stocks at the stop-loss price, and shares have to be sold at an even lower price. Also, what will you do once the position is sold? The reason you invested in the stock market was to avoid holding cash, so would you buy the same stock back when the crash bottoms? But how will you know when the bottom has been reached?

Backtesting stock market strategies with Python, YFinance, Pandas and Lightweight Charts I am not a professional investor, and nobody should take investment advice from me. However, I know what backtesting is and how to leverage open source software. So, I wrote a Python script to test if the trading strategy of using trailing stop-loss orders with specific margin values would have worked for a particular stock. First you need to have data. YFinance is a handy Python library that can be used to download the historic price data for any stock ticker on Yahoo.com. Then you need to manipulate the data. Pandas is the Python data analysis library with advanced data structures for working with relational or labeled data. Finally, to visualize the results, I used Lightweight Charts, which is a fast, interactive library for rendering financial charts, allowing you to plot the stock price, the trailing stop-loss line, and the points where trades would have occurred. I really like how the zoom is implemented in Lightweight Charts, which makes drilling into the data points feel effortless. The full solution is not polished enough to be published for others to use, but you can piece together your own by reusing some of the key snippets. To avoid re-downloading the same data repeatedly, I implemented a small caching wrapper that saves the data locally (as Parquet files):
python 
CACHE_DIR.mkdir(parents=True, exist_ok=True)
end_date = datetime.today().strftime("%Y-%m-%d")
cache_file = CACHE_DIR / f" TICKER - START_DATE -- end_date .parquet"

if cache_file.is_file():
 dataframe = pandas.read_parquet(cache_file)
 print(f"Loaded price data from cache:  cache_file ")
else:
 dataframe = yfinance.download(
 TICKER,
 start=START_DATE,
 end=end_date,
 progress=False,
 auto_adjust=False
 )

 dataframe.to_parquet(cache_file)
 print(f"Fetched new price data from Yahoo Finance and cached to:  cache_file ")
The dataframe is a Pandas object with a powerful API. For example, to print a snippet from the beginning and the end of the dataframe to see what the data looks like, you can use:
python 
print("First 5 rows of the raw data:")
print(df.head())
print("Last 5 rows of the raw data:")
print(df.tail())
Example output: 
First 5 rows of the raw data
Price Adj Close Close High Low Open Volume
Ticker BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA
Date
2014-01-02 29.956285 55.540001 56.910000 55.349998 56.700001 316552
2014-01-03 30.031801 55.680000 55.990002 55.290001 55.580002 210044
2014-01-06 30.080338 55.770000 56.230000 55.529999 55.560001 185142
2014-01-07 30.943321 57.369999 57.619999 55.790001 55.880001 370397
2014-01-08 31.385597 58.189999 59.209999 57.750000 57.790001 489940
Last 5 rows of the raw data
Price Adj Close Close High Low Open Volume
Ticker BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA
Date
2025-12-11 78.669998 78.669998 78.919998 76.900002 76.919998 357918
2025-12-12 78.089996 78.089996 80.269997 78.089996 79.470001 280477
2025-12-15 79.080002 79.080002 79.449997 78.559998 78.559998 233852
2025-12-16 78.860001 78.860001 79.980003 78.809998 79.430000 283057
2025-12-17 80.080002 80.080002 80.150002 79.080002 79.199997 262818
Adding new columns to the dataframe is easy. For example, I used a custom function to calculate the Relative Strength Index (RSI). To add a new column RSI with a value for every row based on the price from that row, only one line of code is needed, without custom loops:
python 
df["RSI"] = compute_rsi(df["price"], period=14)
After manipulating the data, the series can be converted into an array structure and printed as JSON into a placeholder in an HTML template:
python 
 baseline_series = [
  "time": ts, "value": val 
 for ts, val in df_plot[["timestamp", BASELINE_LABEL]].itertuples(index=False)
 ]

 baseline_json = json.dumps(baseline_series)
 template = jinja2.Template("template.html")
 rendered_html = template.render(
 title=title,
 heading=heading,
 description=description_html,
 ...
 baseline_json=baseline_json,
 ...
 )

 with open("report.html", "w", encoding="utf-8") as f:
 f.write(rendered_html)
 print("Report generated!")
In the HTML template, the marker variable in Jinja syntax gets replaced with the actual JSON:
html 
<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>  title  </title>
 ...
</head>
<body>
 <h1>  heading  </h1>
 <div id="chart"></div>
 <script>
 // Ensure the DOM is ready before we initialise the chart
 document.addEventListener('DOMContentLoaded', () =>  
 // Parse the JSON data passed from Python
 const baselineData =   baseline_json   safe  ;
 const strategyData =   strategy_json   safe  ;
 const markersData =   markers_json   safe  ;

 // Create the chart
 const chart = LightweightCharts.createChart(document.getElementById('chart'),  
 width: document.getElementById('chart').clientWidth,
 height: 500,
 layout:  
 background:   color: "#222"  ,
 textColor: "#ccc"
  ,
 grid:  
 vertLines:   color: "#555"  ,
 horzLines:   color: "#555"  
  
  );

 // Add baseline series
 const baselineSeries = chart.addLineSeries( 
 title: '  baseline_label  ',
 lastValueVisible: false,
 priceLineVisible: false,
 priceLineWidth: 1
  );
 baselineSeries.setData(baselineData);

 baselineSeries.priceScale().applyOptions( 
 entireTextOnly: true
  );

 // Add strategy series
 const strategySeries = chart.addLineSeries( 
 title: '  strategy_label  ',
 lastValueVisible: false,
 priceLineVisible: false,
 color: '#FF6D00'
  );
 strategySeries.setData(strategyData);

 // Add buy/sell markers to the strategy series
 strategySeries.setMarkers(markersData);

 // Fit the chart to show the full data range (full zoom)
 chart.timeScale().fitContent();
  )
 </script>
</body>
</html>
There are also Python libraries built specifically for backtesting investment strategies, such as Backtrader and Zipline, but they do not seem to be actively maintained, and probably have too many features and complexity compared to what I needed for doing this simple test. The screenshot below shows an example of backtesting a strategy on the Waste Management Inc stock from January 2015 to December 2025. The baseline Buy and hold scenario is shown as the blue line and it fully tracks the stock price, while the orange line shows how the strategy would have performed, with markers for the sells and buys along the way. Backtest run example

Results I experimented with multiple strategies and tested them with various parameters, but I don t think I found a strategy that was consistently and clearly better than just buy-and-hold. It basically boils down to the fact that I was not able to find any way to calculate when the crash has bottomed based on historical data. You can only know in hindsight that the price has stopped dropping and is on a steady path to recovery, but at that point it is already too late to buy in. In my testing, most strategies underperformed buy-and-hold because they sold when the crash started, but bought back after it recovered at a slightly higher price. In particular when using narrow margins and selling on a 3-6% drawdown the strategy performed very badly, as those small dips tend to recover in a few days. Essentially, the strategy was repeating the pattern of selling 100 stocks at a 6% discount, then being able to buy back only 94 shares the next day, then again selling 94 shares at a 6% discount, and only being able to buy back maybe 90 shares after recovery, and so forth, never catching up to the buy-and-hold. The strategy worked better in large market crashes as they tended to last longer, and there were higher chances of buying back the shares while the price was still low. For example, in the 2020 crash selling at a 20% drawdown was a good strategy, as the stock I tested dropped nearly 50% and remained low for several weeks; thus, the strategy bought back the stocks while the price was still low and had not yet started to climb significantly. But that was just a lucky incident, as the delta between the trailing stop-loss margin of 20% and total crash of 50% was large enough. If the crash had been only 25%, the strategy would have missed the rebound and ended up buying back the stocks at a slightly higher price. Also, note that the simulation assumes that the trade itself is too small to affect the price formation. We should keep in mind that in reality, if many people have stop-loss orders in place, a large price drop would trigger all of them, creating a flood of sell orders, which in turn would affect the price and drive it lower even faster and deeper. Luckily, it seems that stop-loss orders are generally not a good strategy, and we don t need to fear that too many people will be using them.

Conclusion Even though using a trailing stop-loss strategy does not seem to help in getting consistently higher returns based on my backtesting, I would still say it is useful in protecting from the downside of stock investing. It can act as a kind of insurance policy to considerably decrease the chances of losing big while increasing the chances of losing a little bit. If you are risk-averse, which I think I probably am, this tradeoff can make sense. I d rather miss out on an initial 50% loss and an overall 3% gain on recovery than have to sit through weeks or months with a 50% loss before the price recovers to prior levels. Most notably, the trailing stop-loss strategy works best if used only once. If it is repeated multiple times, the small losses in gains will compound into big losses overall. Thus, I think I might actually put this automation in place at least on the stocks in my portfolio that have had the highest gains. If they keep going up, I will ride along, but once the crash happens, I will be out of those particular stocks permanently. Do you have a favorite open source investment tool or are you aware of any strategy that actually works? Comment below!

1 December 2025

Russ Allbery: Review: Forever and a Day

Review: Forever and a Day, by Haley Cass
Series: Those Who Wait #1.5
Publisher: Haley Cass
Copyright: 2020
ISBN: 979-8-5902-5966-3
Format: Kindle
Pages: 101
Forever and a Day is a coda to Haley Cass's self-published sapphic romance novel Those Who Wait. There is no point in reading it unless you have already read and enjoyed the full book and wanted more of a denouement. Given that Those Who Wait is a romance novel, it is definitionally not a spoiler to reveal that Sutton and Charlotte ended up together. This novella is seven scenes sketching out the next few years of their lives, interspersed with press clippings and social media commentary. These tie up loose ends, give the characters a bit more time together, throw in one more conflict and resolution, add one more sex scene, and stick a few exclamation points after the happily ever after. I am the sort of person who likes long denouements in stories, so I'm the target audience for this sort of sequel that's essentially additional chapters to the book. (The funniest version of this I've read is Jacqueline Carey's Saints Astray.) They are usually not great literature, since there are good reasons for not including these chapters in the book. That is exactly what this is: a few more chapters of the characters being happy, entirely forgettable, and of interest only to people who want that. Cass does try to introduce a bit of a plot via some light family conflict, which was sweet and mostly worked, and some conflict over having children, which was very stereotyped and which I did not enjoy as much. I thought the earlier chapters of this novella were the stronger ones, although I do have to give the characters credit in the later chapters for working through conflict in a mature and fairly reasonable way. It does help, though, when the conflict is entirely resolved by one character being right and the other character being happily wrong. That's character conflict on easy mode. I was happy to see that Sutton got a career, although as in the novel I wish Cass had put some more effort into describing Sutton's efforts in building that career. The details are maddeningly vague, which admittedly matches the maddeningly vague description of Charlotte's politics but which left me unsatisfied. Charlotte's political career continues to be pure wish fulfillment in the most utterly superficial and trivialized way, and it bothered me even more in the novella than it did in the novel. We still have absolutely no idea what she stands for, what she wants to accomplish, and why anyone would vote for her, and yet we get endless soft-focus paeans to how wonderful she will be for the country. Her opponents are similarly vague to the point that the stereotypes Cass uses to signal their inferiority to Charlotte are a little suspect. I'm more critical of this in 2025 than I would have been in 2015 because the last ten years have made clear the amount of damage an absolute refusal to stand for anything except hazy bromides causes, and I probably shouldn't be this annoyed that Cass chose to vaguely gesture towards progressive liberalism without muddying her romance denouement with a concrete political debate. But, just, gah. I found the last chapter intensely annoying, in part because the narrative of that chapter was too cliched and trite to sufficiently distract me from the bad taste of the cotton-candy politics. Other than that, this was minor, sweet, and forgettable. If you want another few chapters of an already long novel, this delivers exactly what you would expect. If the novel was plenty, nothing about this novella is going to change your mind and you can safely skip it. I really liked the scene between Charlotte and Sutton's mom, though, and I'm glad I read the novella just for that. Rating: 6 out of 10

15 November 2025

Andrew Cater: 2025-11-15 17:16 UTC Debian media testing for point release 13.2 of Trixie

*Busy* day in Cambridge. A roomful of people, large numbers of laptops and a lot of parallel installations.

Joined here by Emyr, Chris, Helen and Simon with Isy doing speech installs from her university accommodation. Two Andy's always makes it interesting. Steve providing breakfast, as ever.

We're almost there: the last test install is being repeated to flush out a possible bug. Other release processes are being done in the background.

Thanks again to Steve for hosting and all the hard work that goes into this from everybody.

19 October 2025

Otto Kek l inen: Could the XZ backdoor have been detected with better Git and Debian packaging practices?

Featured image of post Could the XZ backdoor have been detected with better Git and Debian packaging practices?The discovery of a backdoor in XZ Utils in the spring of 2024 shocked the open source community, raising critical questions about software supply chain security. This post explores whether better Debian packaging practices could have detected this threat, offering a guide to auditing packages and suggesting future improvements. The XZ backdoor in versions 5.6.0/5.6.1 made its way briefly into many major Linux distributions such as Debian and Fedora, but luckily didn t reach that many actual users, as the backdoored releases were quickly removed thanks to the heroic diligence of Andres Freund. We are all extremely lucky that he detected a half a second performance regression in SSH, cared enough to trace it down, discovered malicious code in the XZ library loaded by SSH, and reported promtly to various security teams for quick coordinated actions. This episode makes software engineers pondering the following questions: As a Debian Developer, I decided to audit the xz package in Debian, share my methodology and findings in this post, and also suggest some improvements on how the software supply-chain security could be tightened in Debian specifically. Note that the scope here is only to inspect how Debian imports software from its upstreams, and how they are distributed to Debian s users. This excludes the whole story of how to assess if an upstream project is following software development security best practices. This post doesn t discuss how to operate an individual computer running Debian to ensure it remains untampered as there are plenty of guides on that already.

Downloading Debian and upstream source packages Let s start by working backwards from what the Debian package repositories offer for download. As auditing binaries is extremely complicated, we skip that, and assume the Debian build hosts are trustworthy and reliably building binaries from the source packages, and the focus should be on auditing the source code packages. As with everything in Debian, there are multiple tools and ways to do the same thing, but in this post only one (and hopefully the best) way to do something is presented for brevity. The first step is to download the latest version and some past versions of the package from the Debian archive, which is easiest done with debsnap. The following command will download all Debian source packages of xz-utils from Debian release 5.2.4-1 onwards: 
$ debsnap --verbose --first 5.2.4-1 xz-utils
Getting json https://snapshot.debian.org/mr/package/xz-utils/
...
Getting dsc file xz-utils_5.2.4-1.dsc: https://snapshot.debian.org/file/a98271e4291bed8df795ce04d9dc8e4ce959462d
Getting file xz-utils_5.2.4.orig.tar.xz.asc: https://snapshot.debian.org/file/59ccbfb2405abe510999afef4b374cad30c09275
Getting file xz-utils_5.2.4-1.debian.tar.xz: https://snapshot.debian.org/file/667c14fd9409ca54c397b07d2d70140d6297393f
source-xz-utils/xz-utils_5.2.4-1.dsc:
Good signature found
validating xz-utils_5.2.4.orig.tar.xz
validating xz-utils_5.2.4.orig.tar.xz.asc
validating xz-utils_5.2.4-1.debian.tar.xz
All files validated successfully.
Once debsnap completes there will be a subfolder source-<package name> with the following types of files:
  • *.orig.tar.xz: source code from upstream
  • *.orig.tar.xz.asc: detached signature (if upstream signs their releases)
  • *.debian.tar.xz: Debian packaging source, i.e. the debian/ subdirectory contents
  • *.dsc: Debian source control file, including signature by Debian Developer/Maintainer
Example: 
$ ls -1 source-xz-utils/
...
xz-utils_5.6.4.orig.tar.xz
xz-utils_5.6.4.orig.tar.xz.asc
xz-utils_5.6.4-1.debian.tar.xz
xz-utils_5.6.4-1.dsc
xz-utils_5.8.0.orig.tar.xz
xz-utils_5.8.0.orig.tar.xz.asc
xz-utils_5.8.0-1.debian.tar.xz
xz-utils_5.8.0-1.dsc
xz-utils_5.8.1.orig.tar.xz
xz-utils_5.8.1.orig.tar.xz.asc
xz-utils_5.8.1-1.1.debian.tar.xz
xz-utils_5.8.1-1.1.dsc
xz-utils_5.8.1-1.debian.tar.xz
xz-utils_5.8.1-1.dsc
xz-utils_5.8.1-2.debian.tar.xz
xz-utils_5.8.1-2.dsc

Verifying authenticity of upstream and Debian sources using OpenPGP signatures As seen in the output of debsnap, it already automatically verifies that the downloaded files match the OpenPGP signatures. To have full clarity on what files were authenticated with what keys, we should verify the Debian packagers signature with: 
$ gpg --verify --auto-key-retrieve --keyserver hkps://keyring.debian.org xz-utils_5.8.1-2.dsc
gpg: Signature made Fri Oct 3 22:04:44 2025 UTC
gpg: using RSA key 57892E705233051337F6FDD105641F175712FA5B
gpg: requesting key 05641F175712FA5B from hkps://keyring.debian.org
gpg: key 7B96E8162A8CF5D1: public key "Sebastian Andrzej Siewior" imported
gpg: Total number processed: 1
gpg: imported: 1
gpg: Good signature from "Sebastian Andrzej Siewior" [unknown]
gpg: aka "Sebastian Andrzej Siewior <bigeasy@linutronix.de>" [unknown]
gpg: aka "Sebastian Andrzej Siewior <sebastian@breakpoint.cc>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg: There is no indication that the signature belongs to the owner.
Primary key fingerprint: 6425 4695 FFF0 AA44 66CC 19E6 7B96 E816 2A8C F5D1
Subkey fingerprint: 5789 2E70 5233 0513 37F6 FDD1 0564 1F17 5712 FA5B
The upstream tarball signature (if available) can be verified with: 
$ gpg --verify --auto-key-retrieve xz-utils_5.8.1.orig.tar.xz.asc
gpg: assuming signed data in 'xz-utils_5.8.1.orig.tar.xz'
gpg: Signature made Thu Apr 3 11:38:23 2025 UTC
gpg: using RSA key 3690C240CE51B4670D30AD1C38EE757D69184620
gpg: key 38EE757D69184620: public key "Lasse Collin <lasse.collin@tukaani.org>" imported
gpg: Total number processed: 1
gpg: imported: 1
gpg: Good signature from "Lasse Collin <lasse.collin@tukaani.org>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg: There is no indication that the signature belongs to the owner.
Primary key fingerprint: 3690 C240 CE51 B467 0D30 AD1C 38EE 757D 6918 4620
Note that this only proves that there is a key that created a valid signature for this content. The authenticity of the keys themselves need to be validated separately before trusting they in fact are the keys of these people. That can be done by checking e.g. the upstream website for what key fingerprints they published, or the Debian keyring for Debian Developers and Maintainers, or by relying on the OpenPGP web-of-trust .

Verifying authenticity of upstream sources by comparing checksums In case the upstream in question does not publish release signatures, the second best way to verify the authenticity of the sources used in Debian is to download the sources directly from upstream and compare that the sha256 checksums match. This should be done using the debian/watch file inside the Debian packaging, which defines where the upstream source is downloaded from. Continuing on the example situation above, we can unpack the latest Debian sources, enter and then run uscan to download: 
$ tar xvf xz-utils_5.8.1-2.debian.tar.xz
...
debian/rules
debian/source/format
debian/source.lintian-overrides
debian/symbols
debian/tests/control
debian/tests/testsuite
debian/upstream/signing-key.asc
debian/watch
...
$ uscan --download-current-version --destdir /tmp
Newest version of xz-utils on remote site is 5.8.1, specified download version is 5.8.1
gpgv: Signature made Thu Apr 3 11:38:23 2025 UTC
gpgv: using RSA key 3690C240CE51B4670D30AD1C38EE757D69184620
gpgv: Good signature from "Lasse Collin <lasse.collin@tukaani.org>"
Successfully symlinked /tmp/xz-5.8.1.tar.xz to /tmp/xz-utils_5.8.1.orig.tar.xz.
The original files downloaded from upstream are now in /tmp along with the files renamed to follow Debian conventions. Using everything downloaded so far the sha256 checksums can be compared across the files and also to what the .dsc file advertised: 
$ ls -1 /tmp/
xz-5.8.1.tar.xz
xz-5.8.1.tar.xz.sig
xz-utils_5.8.1.orig.tar.xz
xz-utils_5.8.1.orig.tar.xz.asc
$ sha256sum xz-utils_5.8.1.orig.tar.xz /tmp/xz-5.8.1.tar.xz
0b54f79df85912504de0b14aec7971e3f964491af1812d83447005807513cd9e xz-utils_5.8.1.orig.tar.xz
0b54f79df85912504de0b14aec7971e3f964491af1812d83447005807513cd9e /tmp/xz-5.8.1.tar.xz
$ grep -A 3 Sha256 xz-utils_5.8.1-2.dsc
Checksums-Sha256:
0b54f79df85912504de0b14aec7971e3f964491af1812d83447005807513cd9e 1461872 xz-utils_5.8.1.orig.tar.xz
4138f4ceca1aa7fd2085fb15a23f6d495d27bca6d3c49c429a8520ea622c27ae 833 xz-utils_5.8.1.orig.tar.xz.asc
3ed458da17e4023ec45b2c398480ed4fe6a7bfc1d108675ec837b5ca9a4b5ccb 24648 xz-utils_5.8.1-2.debian.tar.xz
In the example above the checksum 0b54f79df85... is the same across the files, so it is a match.

Repackaged upstream sources can t be verified as easily Note that uscan may in rare cases repackage some upstream sources, for example to exclude files that don t adhere to Debian s copyright and licensing requirements. Those files and paths would be listed under the Files-Excluded section in the debian/copyright file. There are also other situations where the file that represents the upstream sources in Debian isn t bit-by-bit the same as what upstream published. If checksums don t match, an experienced Debian Developer should review all package settings (e.g. debian/source/options) to see if there was a valid and intentional reason for divergence.

Reviewing changes between two source packages using diffoscope Diffoscope is an incredibly capable and handy tool to compare arbitrary files. For example, to view a report in HTML format of the differences between two XZ releases, run: 
diffoscope --html-dir xz-utils-5.6.4_vs_5.8.0 xz-utils_5.6.4.orig.tar.xz xz-utils_5.8.0.orig.tar.xz
browse xz-utils-5.6.4_vs_5.8.0/index.html
Inspecting diffoscope output of differences between two XZ Utils releases If the changes are extensive, and you want to use a LLM to help spot potential security issues, generate the report of both the upstream and Debian packaging differences in Markdown with: 
diffoscope --markdown diffoscope-debian.md xz-utils_5.6.4-1.debian.tar.xz xz-utils_5.8.1-2.debian.tar.xz
diffoscope --markdown diffoscope.md xz-utils_5.6.4.orig.tar.xz xz-utils_5.8.0.orig.tar.xz
The Markdown files created above can then be passed to your favorite LLM, along with a prompt such as:
Based on the attached diffoscope output for a new Debian package version compared with the previous one, list all suspicious changes that might have introduced a backdoor, followed by other potential security issues. If there are none, list a short summary of changes as the conclusion.

Reviewing Debian source packages in version control As of today only 93% of all Debian source packages are tracked in git on Debian s GitLab instance at salsa.debian.org. Some key packages such as Coreutils and Bash are not using version control at all, as their maintainers apparently don t see value in using git for Debian packaging, and the Debian Policy does not require it. Thus, the only reliable and consistent way to audit changes in Debian packages is to compare the full versions from the archive as shown above. However, for packages that are hosted on Salsa, one can view the git history to gain additional insight into what exactly changed, when and why. For packages that are using version control, their location can be found in the Git-Vcs header in the debian/control file. For xz-utils the location is salsa.debian.org/debian/xz-utils. Note that the Debian policy does not state anything about how Salsa should be used, or what git repository layout or development practices to follow. In practice most packages follow the DEP-14 proposal, and use git-buildpackage as the tool for managing changes and pushing and pulling them between upstream and salsa.debian.org. To get the XZ Utils source, run: 
$ gbp clone https://salsa.debian.org/debian/xz-utils.git
gbp:info: Cloning from 'https://salsa.debian.org/debian/xz-utils.git'
At the time of writing this post the git history shows: 
$ git log --graph --oneline
* bb787585 (HEAD -> debian/unstable, origin/debian/unstable, origin/HEAD) Prepare 5.8.1-2
* 4b769547 d: Remove the symlinks from -dev package.
* a39f3428 Correct the nocheck build profile
* 1b806b8d Import Debian changes 5.8.1-1.1
* b1cad34b Prepare 5.8.1-1
* a8646015 Import 5.8.1
* 2808ec2d Update upstream source from tag 'upstream/5.8.1'
 \
  * fa1e8796 (origin/upstream/v5.8, upstream/v5.8) New upstream version 5.8.1
  * a522a226 Bump version and soname for 5.8.1
  * 1c462c2a Add NEWS for 5.8.1
  * 513cabcf Tests: Call lzma_code() in smaller chunks in fuzz_common.h
  * 48440e24 Tests: Add a fuzzing target for the multithreaded .xz decoder
  * 0c80045a liblzma: mt dec: Fix lack of parallelization in single-shot decoding
  * 81880488 liblzma: mt dec: Don't modify thr->in_size in the worker thread
  * d5a2ffe4 liblzma: mt dec: Don't free the input buffer too early (CVE-2025-31115)
  * c0c83596 liblzma: mt dec: Simplify by removing the THR_STOP state
  * 831b55b9 liblzma: mt dec: Fix a comment
  * b9d168ee liblzma: Add assertions to lzma_bufcpy()
  * c8e0a489 DOS: Update Makefile to fix the build
  * 307c02ed sysdefs.h: Avoid <stdalign.h> even with C11 compilers
  * 7ce38b31 Update THANKS
  * 688e51bd Translations: Update the Croatian translation
*   a6b54dde Prepare 5.8.0-1.
*   77d9470f Add 5.8 symbols.
*   9268eb66 Import 5.8.0
*   6f85ef4f Update upstream source from tag 'upstream/5.8.0'
 \ \
  *   afba662b New upstream version 5.8.0
   /
  * 173fb5c6 doc/SHA256SUMS: Add 5.8.0
  * db9258e8 Bump version and soname for 5.8.0
  * bfb752a3 Add NEWS for 5.8.0
  * 6ccbb904 Translations: Run "make -C po update-po"
  * 891a5f05 Translations: Run po4a/update-po
  * 4f52e738 Translations: Partially fix overtranslation in Serbian man pages
  * ff5d9447 liblzma: Count the extra bytes in LZMA/LZMA2 decoder memory usage
  * 943b012d liblzma: Use SSE2 intrinsics instead of memcpy() in dict_repeat()
This shows both the changes on the debian/unstable branch as well as the intermediate upstream import branch, and the actual real upstream development branch. See my Debian source packages in git explainer for details of what these branches are used for. To only view changes on the Debian branch, run git log --graph --oneline --first-parent or git log --graph --oneline -- debian. The Debian branch should only have changes inside the debian/ subdirectory, which is easy to check with: 
$ git diff --stat upstream/v5.8
debian/README.source   16 +++
debian/autogen.sh   32 +++++
debian/changelog   949 ++++++++++++++++++++++++++
...
debian/upstream/signing-key.asc   52 +++++++++
debian/watch   4 +
debian/xz-utils.README.Debian   47 ++++++++
debian/xz-utils.docs   6 +
debian/xz-utils.install   28 +++++
debian/xz-utils.postinst   19 +++
debian/xz-utils.prerm   10 ++
debian/xzdec.docs   6 +
debian/xzdec.install   4 +
33 files changed, 2014 insertions(+)
All the files outside the debian/ directory originate from upstream, and for example running git blame on them should show only upstream commits: 
$ git blame CMakeLists.txt
22af94128 (Lasse Collin 2024-02-12 17:09:10 +0200 1) # SPDX-License-Identifier: 0BSD
22af94128 (Lasse Collin 2024-02-12 17:09:10 +0200 2)
7e3493d40 (Lasse Collin 2020-02-24 23:38:16 +0200 3) ###############
7e3493d40 (Lasse Collin 2020-02-24 23:38:16 +0200 4) #
426bdc709 (Lasse Collin 2024-02-17 21:45:07 +0200 5) # CMake support for building XZ Utils
If the upstream in question signs commits or tags, they can be verified with e.g.: 
$ git verify-tag v5.6.2
gpg: Signature made Wed 29 May 2024 09:39:42 AM PDT
gpg: using RSA key 3690C240CE51B4670D30AD1C38EE757D69184620
gpg: issuer "lasse.collin@tukaani.org"
gpg: Good signature from "Lasse Collin <lasse.collin@tukaani.org>" [expired]
gpg: Note: This key has expired!
The main benefit of reviewing changes in git is the ability to see detailed information about each individual change, instead of just staring at a massive list of changes without any explanations. In this example, to view all the upstream commits since the previous import to Debian, one would view the commit range from afba662b New upstream version 5.8.0 to fa1e8796 New upstream version 5.8.1 with git log --reverse -p afba662b...fa1e8796. However, a far superior way to review changes would be to browse this range using a visual git history viewer, such as gitk. Either way, looking at one code change at a time and reading the git commit message makes the review much easier. Browsing git history in gitk --all

Comparing Debian source packages to git contents As stated in the beginning of the previous section, and worth repeating, there is no guarantee that the contents in the Debian packaging git repository matches what was actually uploaded to Debian. While the tag2upload project in Debian is getting more and more popular, Debian is still far from having any system to enforce that the git repository would be in sync with the Debian archive contents. To detect such differences we can run diff across the Debian source packages downloaded with debsnap earlier (path source-xz-utils/xz-utils_5.8.1-2.debian) and the git repository cloned in the previous section (path xz-utils):
diff 
$ diff -u source-xz-utils/xz-utils_5.8.1-2.debian/ xz-utils/debian/
diff -u source-xz-utils/xz-utils_5.8.1-2.debian/changelog xz-utils/debian/changelog
--- debsnap/source-xz-utils/xz-utils_5.8.1-2.debian/changelog 2025-10-03 09:32:16.000000000 -0700
+++ xz-utils/debian/changelog 2025-10-12 12:18:04.623054758 -0700
@@ -5,7 +5,7 @@
 * Remove the symlinks from -dev, pointing to the lib package.
 (Closes: #1109354)

- -- Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Fri, 03 Oct 2025 18:32:16 +0200
+ -- Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Fri, 03 Oct 2025 18:36:59 +0200
In the case above diff revealed that the timestamp in the changelog in the version uploaded to Debian is different from what was committed to git. This is not malicious, just a mistake by the maintainer who probably didn t run gbp tag immediately after upload, but instead some dch command and ended up with having a different timestamps in the git compared to what was actually uploaded to Debian.

Creating syntetic Debian packaging git repositories If no Debian packaging git repository exists, or if it is lagging behind what was uploaded to Debian s archive, one can use git-buildpackage s import-dscs feature to create synthetic git commits based on the files downloaded by debsnap, ensuring the git contents fully matches what was uploaded to the archive. To import a single version there is gbp import-dsc (no s at the end), of which an example invocation would be: 
$ gbp import-dsc --verbose ../source-xz-utils/xz-utils_5.8.1-2.dsc
Version '5.8.1-2' imported under '/home/otto/debian/xz-utils-2025-09-29'
Example commit history from a repository with commits added with gbp import-dsc: 
$ git log --graph --oneline
* 86aed07b (HEAD -> debian/unstable, tag: debian/5.8.1-2, origin/debian/unstable) Import Debian changes 5.8.1-2
* f111d93b (tag: debian/5.8.1-1.1) Import Debian changes 5.8.1-1.1
* 1106e19b (tag: debian/5.8.1-1) Import Debian changes 5.8.1-1
 \
  * 08edbe38 (tag: upstream/5.8.1, origin/upstream/v5.8, upstream/v5.8) Import Upstream version 5.8.1
   \
    * a522a226 (tag: v5.8.1) Bump version and soname for 5.8.1
    * 1c462c2a Add NEWS for 5.8.1
    * 513cabcf Tests: Call lzma_code() in smaller chunks in fuzz_common.h
An online example repository with only a few missing uploads added using gbp import-dsc can be viewed at salsa.debian.org/otto/xz-utils-2025-09-29/-/network/debian%2Funstable An example repository that was fully crafted using gbp import-dscs can be viewed at salsa.debian.org/otto/xz-utils-gbp-import-dscs-debsnap-generated/-/network/debian%2Flatest. There exists also dgit, which in a similar way creates a synthetic git history to allow viewing the Debian archive contents via git tools. However, its focus is on producing new package versions, so fetching a package with dgit that has not had the history recorded in dgit earlier will only show the latest versions: 
$ dgit clone xz-utils
canonical suite name for unstable is sid
starting new git history
last upload to archive: NO git hash
downloading http://ftp.debian.org/debian//pool/main/x/xz-utils/xz-utils_5.8.1.orig.tar.xz...
downloading http://ftp.debian.org/debian//pool/main/x/xz-utils/xz-utils_5.8.1.orig.tar.xz.asc...
downloading http://ftp.debian.org/debian//pool/main/x/xz-utils/xz-utils_5.8.1-2.debian.tar.xz...
dpkg-source: info: extracting xz-utils in unpacked
dpkg-source: info: unpacking xz-utils_5.8.1.orig.tar.xz
dpkg-source: info: unpacking xz-utils_5.8.1-2.debian.tar.xz
synthesised git commit from .dsc 5.8.1-2
HEAD is now at f9bcaf7 xz-utils (5.8.1-2) unstable; urgency=medium
dgit ok: ready for work in xz-utils
$ dgit/sid   git log --graph --oneline
* f9bcaf7 xz-utils (5.8.1-2) unstable; urgency=medium 9 days ago (HEAD -> dgit/sid, dgit/dgit/sid)
 \
  * 11d3a62 Import xz-utils_5.8.1-2.debian.tar.xz 9 days ago
* 15dcd95 Import xz-utils_5.8.1.orig.tar.xz 6 months ago
Unlike git-buildpackage managed git repositories, the dgit managed repositories cannot incorporate the upstream git history and are thus less useful for auditing the full software supply-chain in git.

Comparing upstream source packages to git contents Equally important to the note in the beginning of the previous section, one must also keep in mind that the upstream release source packages, often called release tarballs, are not guaranteed to have the exact same contents as the upstream git repository. Projects might strip out test data or extra development files from their release tarballs to avoid shipping unnecessary files to users, or projects might add documentation files or versioning information into the tarball that isn t stored in git. While a small minority, there are also upstreams that don t use git at all, so the plain files in a release tarball is still the lowest common denominator for all open source software projects, and exporting and importing source code needs to interface with it. In the case of XZ, the release tarball has additional version info and also a sizeable amount of pregenerated compiler configuration files. Detecting and comparing differences between git contents and tarballs can of course be done manually by running diff across an unpacked tarball and a checked out git repository. If using git-buildpackage, the difference between the git contents and tarball contents can be made visible directly in the import commit. In this XZ example, consider this git history: 
* b1cad34b Prepare 5.8.1-1
* a8646015 Import 5.8.1
* 2808ec2d Update upstream source from tag 'upstream/5.8.1'
 \
  * fa1e8796 (debian/upstream/v5.8, upstream/v5.8) New upstream version 5.8.1
  * a522a226 (tag: v5.8.1) Bump version and soname for 5.8.1
  * 1c462c2a Add NEWS for 5.8.1
The commit a522a226 was the upstream release commit, which upstream also tagged v5.8.1. The merge commit 2808ec2d applied the new upstream import branch contents on the Debian branch. Between these is the special commit fa1e8796 New upstream version 5.8.1 tagged upstream/v5.8. This commit and tag exists only in the Debian packaging repository, and they show what is the contents imported into Debian. This is generated automatically by git-buildpackage when running git import-orig --uscan for Debian packages with the correct settings in debian/gbp.conf. By viewing this commit one can see exactly how the upstream release tarball differs from the upstream git contents (if at all). In the case of XZ, the difference is substantial, and shown below in full as it is very interesting: 
$ git show --stat fa1e8796
commit fa1e8796dabd91a0f667b9e90f9841825225413a
(debian/upstream/v5.8, upstream/v5.8)
Author: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Date: Thu Apr 3 22:58:39 2025 +0200
New upstream version 5.8.1
.codespellrc   30 -
.gitattributes   8 -
.github/workflows/ci.yml   163 -
.github/workflows/freebsd.yml   32 -
.github/workflows/netbsd.yml   32 -
.github/workflows/openbsd.yml   35 -
.github/workflows/solaris.yml   32 -
.github/workflows/windows-ci.yml   124 -
.gitignore   113 -
ABOUT-NLS   1 +
ChangeLog   17392 +++++++++++++++++++++
Makefile.in   1097 +++++++
aclocal.m4   1353 ++++++++
build-aux/ci_build.bash   286 --
build-aux/compile   351 ++
build-aux/config.guess   1815 ++++++++++
build-aux/config.rpath   751 +++++
build-aux/config.sub   2354 +++++++++++++
build-aux/depcomp   792 +++++
build-aux/install-sh   541 +++
build-aux/ltmain.sh   11524 ++++++++++++++++++++++
build-aux/missing   236 ++
build-aux/test-driver   160 +
config.h.in   634 ++++
configure   26434 ++++++++++++++++++++++
debug/Makefile.in   756 +++++
doc/SHA256SUMS   236 --
doc/man/txt/lzmainfo.txt   36 +
doc/man/txt/xz.txt   1708 ++++++++++
doc/man/txt/xzdec.txt   76 +
doc/man/txt/xzdiff.txt   39 +
doc/man/txt/xzgrep.txt   70 +
doc/man/txt/xzless.txt   36 +
doc/man/txt/xzmore.txt   31 +
lib/Makefile.in   623 ++++
m4/.gitignore   40 -
m4/build-to-host.m4   274 ++
m4/gettext.m4   392 +++
m4/host-cpu-c-abi.m4   529 +++
m4/iconv.m4   324 ++
m4/intlmacosx.m4   71 +
m4/lib-ld.m4   170 +
m4/lib-link.m4   815 +++++
m4/lib-prefix.m4   334 ++
m4/libtool.m4   8488 +++++++++++++++++++++
m4/ltoptions.m4   467 +++
m4/ltsugar.m4   124 +
m4/ltversion.m4   24 +
m4/lt~obsolete.m4   99 +
m4/nls.m4   33 +
m4/po.m4   456 +++
m4/progtest.m4   92 +
po/.gitignore   31 -
po/Makefile.in.in   517 +++
po/Rules-quot   66 +
po/boldquot.sed   21 +
po/ca.gmo   Bin 0 -> 15587 bytes
po/cs.gmo   Bin 0 -> 7983 bytes
po/da.gmo   Bin 0 -> 9040 bytes
po/de.gmo   Bin 0 -> 29882 bytes
po/en@boldquot.header   35 +
po/en@quot.header   32 +
po/eo.gmo   Bin 0 -> 15060 bytes
po/es.gmo   Bin 0 -> 29228 bytes
po/fi.gmo   Bin 0 -> 28225 bytes
po/fr.gmo   Bin 0 -> 10232 bytes
To be able to easily inspect exactly what changed in the release tarball compared to git release tag contents, the best tool for the job is Meld, invoked via git difftool --dir-diff fa1e8796^..fa1e8796. Meld invoked by git difftool --dir-diff afba662b..fa1e8796 to show differences between git release tag and release tarball contents To compare changes across the new and old upstream tarball, one would need to compare commits afba662b New upstream version 5.8.0 and fa1e8796 New upstream version 5.8.1 by running git difftool --dir-diff afba662b..fa1e8796. Meld invoked by git difftool --dir-diff afba662b..fa1e8796 to show differences between to upstream release tarball contents With all the above tips you can now go and try to audit your own favorite package in Debian and see if it is identical with upstream, and if not, how it differs.

Should the XZ backdoor have been detected using these tools? The famous XZ Utils backdoor (CVE-2024-3094) consisted of two parts: the actual backdoor inside two binary blobs masqueraded as a test files (tests/files/bad-3-corrupt_lzma2.xz, tests/files/good-large_compressed.lzma), and a small modification in the build scripts (m4/build-to-host.m4) to extract the backdoor and plant it into the built binary. The build script was not tracked in version control, but generated with GNU Autotools at release time and only shipped as additional files in the release tarball. The entire reason for me to write this post was to ponder if a diligent engineer using git-buildpackage best practices could have reasonably spotted this while importing the new upstream release into Debian. The short answer is no . The malicious actor here clearly anticipated all the typical ways anyone might inspect both git commits, and release tarball contents, and masqueraded the changes very well and over a long timespan. First of all, XZ has for legitimate reasons for several carefully crafted .xz files as test data to help catch regressions in the decompression code path. The test files are shipped in the release so users can run the test suite and validate that the binary is built correctly and xz works properly. Debian famously runs massive amounts of testing in its CI and autopkgtest system across tens of thousands of packages to uphold high quality despite frequent upgrades of the build toolchain and while supporting more CPU architectures than any other distro. Test data is useful and should stay. When git-buildpackage is used correctly, the upstream commits are visible in the Debian packaging for easy review, but the commit cf44e4b that introduced the test files does not deviate enough from regular sloppy coding practices to really stand out. It is unfortunately very common for git commit to lack a message body explaining why the change was done, and to not be properly atomic with test code and test data together in the same commit, and for commits to be pushed directly to mainline without using code reviews (the commit was not part of any PR in this case). Only another upstream developer could have spotted that this change is not on par to what the project expects, and that the test code was never added, only test data, and thus that this commit was not just a sloppy one but potentially malicious. Secondly, the fact that a new Autotools file appeared (m4/build-to-host.m4) in the XZ Utils 5.6.0 is not suspicious. This is perfectly normal for Autotools. In fact, starting from XZ Utils version 5.8.1 it is now shipping a m4/build-to-host.m4 file that it actually uses now. Spotting that there is anything fishy is practically impossible by simply reading the code, as Autotools files are full custom m4 syntax interwoven with shell script, and there are plenty of backticks ( ) that spawn subshells and evals that execute variable contents further, which is just normal for Autotools. Russ Cox s XZ post explains how exactly the Autotools code fetched the actual backdoor from the test files and injected it into the build. Inspecting the m4/build-to-host.m4 changes in Meld launched via git difftool There is only one tiny thing that maybe a very experienced Autotools user could potentially have noticed: the serial 30 in the version header is way too high. In theory one could also have noticed this Autotools file deviates from what other packages in Debian ship with the same filename, such as e.g. the serial 3, serial 5a or 5b versions. That would however require and an insane amount extra checking work, and is not something we should plan to start doing. A much simpler solution would be to simply strongly recommend all open source projects to stop using Autotools to eventually get rid of it entirely.

Not detectable with reasonable effort While planting backdoors is evil, it is hard not to feel some respect to the level of skill and dedication of the people behind this. I ve been involved in a bunch of security breach investigations during my IT career, and never have I seen anything this well executed. If it hadn t slowed down SSH by ~500 milliseconds and been discovered due to that, it would most likely have stayed undetected for months or years. Hiding backdoors in closed source software is relatively trivial, but hiding backdoors in plain sight in a popular open source project requires some unusual amount of expertise and creativity as shown above.

Is the software supply-chain in Debian easy to audit? While maintaining a Debian package source using git-buildpackage can make the package history a lot easier to inspect, most packages have incomplete configurations in their debian/gbp.conf, and thus their package development histories are not always correctly constructed or uniform and easy to compare. The Debian Policy does not mandate git usage at all, and there are many important packages that are not using git at all. Additionally the Debian Policy also allows for non-maintainers to upload new versions to Debian without committing anything in git even for packages where the original maintainer wanted to use git. Uploads that bypass git unfortunately happen surpisingly often. Because of the situation, I am afraid that we could have multiple similar backdoors lurking that simply haven t been detected yet. More audits, that hopefully also get published openly, would be welcome! More people auditing the contents of the Debian archives would probably also help surface what tools and policies Debian might be missing to make the work easier, and thus help improve the security of Debian s users, and improve trust in Debian.

Is Debian currently missing some software that could help detect similar things? To my knowledge there is currently no system in place as part of Debian s QA or security infrastructure to verify that the upstream source packages in Debian are actually from upstream. I ve come across a lot of packages where the debian/watch or other configs are incorrect and even cases where maintainers have manually created upstream tarballs as it was easier than configuring automation to work. It is obvious that for those packages the source tarball now in Debian is not at all the same as upstream. I am not aware of any malicious cases though (if I was, I would report them of course). I am also aware of packages in the Debian repository that are misconfigured to be of type 1.0 (native) packages, mixing the upstream files and debian/ contents and having patches applied, while they actually should be configured as 3.0 (quilt), and not hide what is the true upstream sources. Debian should extend the QA tools to scan for such things. If I find a sponsor, I might build it myself as my next major contribution to Debian. In addition to better tooling for finding mismatches in the source code, Debian could also have better tooling for tracking in built binaries what their source files were, but solutions like Fraunhofer-AISEC s supply-graph or Sony s ESSTRA are not practical yet. Julien Malka s post about NixOS discusses the role of reproducible builds, which may help in some cases across all distros.

Or, is Debian missing some policies or practices to mitigate this? Perhaps more importantly than more security scanning, the Debian Developer community should switch the general mindset from anyone is free to do anything to valuing having more shared workflows. The ability to audit anything is severely hampered by the fact that there are so many ways to do the same thing, and distinguishing what is a normal deviation from a malicious deviation is too hard, as the normal can basically be almost anything. Also, as there is no documented and recommended default workflow, both those who are old and new to Debian packaging might never learn any one optimal workflow, and end up doing many steps in the packaging process in a way that kind of works, but is actually wrong or unnecessary, causing process deviations that look malicious, but turn out to just be a result of not fully understanding what would have been the right way to do something. In the long run, once individual developers workflows are more aligned, doing code reviews will become a lot easier and smoother as the excess noise of workflow differences diminishes and reviews will feel much more productive to all participants. Debian fostering a culture of code reviews would allow us to slowly move from the current practice of mainly solo packaging work towards true collaboration forming around those code reviews. I have been promoting increased use of Merge Requests in Debian already for some time, for example by proposing DEP-18: Encourage Continuous Integration and Merge Request based Collaboration for Debian packages. If you are involved in Debian development, please give a thumbs up in dep-team/deps!21 if you want me to continue promoting it.

Can we trust open source software? Yes and I would argue that we can only trust open source software. There is no way to audit closed source software, and anyone using e.g. Windows or MacOS just have to trust the vendor s word when they say they have no intentional or accidental backdoors in their software. Or, when the news gets out that the systems of a closed source vendor was compromised, like Crowdstrike some weeks ago, we can t audit anything, and time after time we simply need to take their word when they say they have properly cleaned up their code base. In theory, a vendor could give some kind of contractual or financial guarantee to its customer that there are no preventable security issues, but in practice that never happens. I am not aware of a single case of e.g. Microsoft or Oracle would have paid damages to their customers after a security flaw was found in their software. In theory you could also pay a vendor more to have them focus more effort in security, but since there is no way to verify what they did, or to get compensation when they didn t, any increased fees are likely just pocketed as increased profit. Open source is clearly better overall. You can, if you are an individual with the time and skills, audit every step in the supply-chain, or you could as an organization make investments in open source security improvements and actually verify what changes were made and how security improved. If your organisation is using Debian (or derivatives, such as Ubuntu) and you are interested in sponsoring my work to improve Debian, please reach out.

9 October 2025

Dirk Eddelbuettel: xptr 1.2.0 on CRAN: New(ly Adopted) Package!

Excited to share that xptr is back on CRAN! The xptr package helps to create, check, modify, use, share, external pointer objects. External pointers are used quite extensively throughout R to manage external resources such as datanbase connection objects and alike, and can be very useful to pass pointers to just about any C / C++ data structure around. While described in Writing R Extensions (notably Section 5.13), they can be a little bare-bones and so this package can be useful. It had been created by Randy Lai and maintained by him during 2017 to 2020, but then fell off CRAN. In work with nanoarrow and its clean and minimal Arrow interface xptr came in handy so I adopted it. Several extensions and updates have been added: (compiled) function registration, continuous integration, tests, refreshed and extended documentation as well as a print format extension useful for PyCapsule objects when passing via reticulate. The package documentation site was switched to altdoc driving the most excellent Material for MkDocs framework (providing my first test case of altdoc replacing my older local scripts; I should post some more about that ). The first NEWS entry follow.

Changes in version 1.2.0 (2025-10-03)
  • New maintainer
  • Compiled functions are now registered, .Call() adjusted
  • README.md and DESCRIPTION edited and update
  • Simple unit tests and continunous integration have been added
  • The package documentation site has been recreated using altdoc
  • All manual pages for functions now contain \value sections

For more, see the package page, the git repo or the documentation site.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can sponsor me at GitHub.

28 August 2025

Samuel Henrique: Debian 13: My list of exciting new features

A bunch of screenshots overlaid on top of each other showing different tools: lazygit, gnome settings, gnome system monitor, powerline-go, and the wcurl logo, the text at the top says 'Debian 13: My list of exciting new features', and there's a Debian logo in the middle of image

Beyond Debian: Useful for other distros too Every two years Debian releases a new major version of its Stable series, meaning the differences between consecutive Debian Stable releases represent two years of new developments both in Debian as an organization and its native packages, but also in all other packages which are also shipped by other distributions (which are getting into this new Stable release). If you're not paying close attention to everything that's going on all the time in the Linux world, you miss a lot of the nice new features and tools. It's common for people to only realize there's a cool new trick available only years after it was first introduced. Given these considerations, the tips that I'm describing will eventually be available in whatever other distribution you use, be it because it's a Debian derivative or because it just got the same feature from the upstream project. I'm not going to list "passive" features (as good as they can be), the focus here is on new features that might change how you configure and use your machine, with a mix between productivity and performance.

Debian 13 - Trixie I have been a Debian Testing user for longer than 10 years now (and I recommend it for non-server users), so I'm not usually keeping track of all the cool features arriving in the new Stable releases because I'm continuously receiving them through the Debian Testing rolling release. Nonetheless, as a Debian Developer I'm in a good position to point out the ones I can remember. I would also like other Debian Developers to do the same as I'm sure I would learn something new. The Debian 13 release notes contain a "What's new" section , which lists the first two items here and a few other things, in other words, take my list as an addition to the release notes. Debian 13 was released on 2025-08-09, and these are nice things you shouldn't miss in the new release, with a bonus one not tied to the Debian 13 release.

1) wcurl wcurl logo Have you ever had to download a file from your terminal using curl and didn't remember the parameters needed? I did. Nowadays you can use wcurl; "a command line tool which lets you download URLs without having to remember any parameters." Simply call wcurl with one or more URLs as parameters and it will download all of them in parallel, performing retries, choosing the correct output file name, following redirects, and more. Try it out: 
wcurl example.com
wcurl comes installed as part of the curl package on Debian 13 and in any other distribution you can imagine, starting with curl 8.14.0. I've written more about wcurl in its release announcement and I've done a lightning talk presentation in DebConf24, which is linked in the release announcement.

2) HTTP/3 support in curl Debian has become the first stable Linux distribution to ship curl with support for HTTP/3. I've written about this in July 2024, when we first enabled it. Note that we first switched the curl CLI to GnuTLS, but then ended up releasing the curl CLI linked with OpenSSL (as support arrived later). Debian was the first stable Linux distro to enable it, and within rolling-release-based distros; Gentoo enabled it first in their non-default flavor of the package and Arch Linux did it three months before we pushed it to Debian Unstable/Testing/Stable-backports, kudos to them! HTTP/3 is not used by default by the curl CLI, you have to enable it with --http3 or --http3-only. Try it out: 
curl --http3 https://www.example.org
curl --http3-only https://www.example.org

3) systemd soft-reboot Starting with systemd v254, there's a new soft-reboot option, it's an userspace-only reboot, much faster than a full reboot if you don't need to reboot the kernel. You can read the announcement from the systemd v254 GitHub release Try it out: 
# This will reboot your machine!
systemctl soft-reboot

4) apt --update Are you tired of being required to run sudo apt update just before sudo apt upgrade or sudo apt install $PACKAGE? So am I! The new --update option lets you do both things in a single command: 
sudo apt --update upgrade
sudo apt --update install $PACKAGE
I love this, but it's still not yet where it should be, fingers crossed for a simple apt upgrade to behave like other package managers by updating its cache as part of the task, maybe in Debian 14? Try it out: 
sudo apt upgrade --update
# The order doesn't matter
sudo apt --update upgrade
This is especially handy for container usage, where you have to update the apt cache before installing anything, for example: 
podman run debian:stable bin/bash -c 'apt install --update -y curl'

5) powerline-go powerline-go is a powerline-style prompt written in Golang, so it's much more performant than its Python alternative powerline. powerline-style prompts are quite useful to show things like the current status of the git repo in your working directory, exit code of the previous command, presence of jobs in the background, whether or not you're in an ssh session, and more. A screenshot of a terminal with powerline-go enabled, showing how the PS1 changes inside a git repository and when the last command fails Try it out: 
sudo apt install powerline-go
Then add this to your .bashrc: 
function _update_ps1()  
    PS1="$(/usr/bin/powerline-go -error $? -jobs $(jobs -p   wc -l))"

    # Uncomment the following line to automatically clear errors after showing
    # them once. This not only clears the error for powerline-go, but also for
    # everything else you run in that shell. Don't enable this if you're not
    # sure this is what you want.

    #set "?"
 

if [ "$TERM" != "linux" ] && [ -f "/usr/bin/powerline-go" ]; then
    PROMPT_COMMAND="_update_ps1; $PROMPT_COMMAND"
fi
Or this to .zshrc: 
function powerline_precmd()  
    PS1="$(/usr/bin/powerline-go -error $? -jobs $ $ (%):%j :-0 )"

    # Uncomment the following line to automatically clear errors after showing
    # them once. This not only clears the error for powerline-go, but also for
    # everything else you run in that shell. Don't enable this if you're not
    # sure this is what you want.

    #set "?"
If you'd like to have your prompt start in a newline, like I have in the screenshot above, you just need to set -newline in the powerline-go invocation in your .bashrc/.zshrc.

6) Gnome System Monitor Extension Tips number 6 and 7 are for Gnome users. Gnome is now shipping a system monitor extension which lets you get a glance of the current load of your machine from the top bar. Screenshot of the top bar of Gnome with the system monitor extension enabled, showing the load of: CPU, memory, network and disk I've found this quite useful for machines where I'm required to install third-party monitoring software that tends to randomly consume more resources than it should. If I feel like my machine is struggling, I can quickly glance at its load to verify if it's getting overloaded by some process. The extension is not as complete as system-monitor-next, not showing temperatures or histograms, but at least it's officially part of Gnome, easy to install and supported by them. Try it out: 
sudo apt install gnome-system-monitor gnome-shell-extension-manager
And then enable the extension from the "Extension Manager" application.

7) Gnome setting for battery charging profile After having to learn more about batteries in order to get into FPV drones, I've come to have a bigger appreciation for solutions that minimize the inevitable loss of capacity that accrues over time. There's now a "Battery Charging" setting (under the "Power") section which lets you choose between two different profiles: "Maximize Charge" and "Preserve Battery Health". A screenshot of the Gnome settings for Power showing the options for Battery Charging On supported laptops, this setting is an easy way to set thresholds for when charging should start and stop, just like you could do it with the tlp package, but now from the Gnome settings. To increase the longevity of my laptop battery, I always keep it at "Preserve Battery Health" unless I'm traveling. What I would like to see next is support for choosing different "Power Modes" based on whether the laptop is plugged-in, and based on the battery charge percentage. There's a GNOME issue tracking this feature, but there's some pushback on whether this is the right thing to expose to users. In the meantime, there are some workarounds mentioned in that issue which people who really want this feature can follow. If you would like to learn more about batteries; Battery University is a great starting point, besides getting into FPV drones and being forced to handle batteries without a Battery Management System (BMS). And if by any chance this sparks your interest in FPV drones, Joshua Bardwell's YouTube channel is a great resource: @JoshuaBardwell.

8) Lazygit Emacs users are already familiar with the legendary magit; a terminal-based UI for git. Lazygit is an alternative for non-emacs users, you can integrate it with neovim or just use it directly. I'm still playing with lazygit and haven't integrated it into my workflows, but so far it has been a pleasant experience. Screenshot of lazygit from the Debian curl repository, showing a selected commit and its diff, besides the other things from the lazygit UI You should check out the demos from the lazygit GitHub page. Try it out: 
sudo apt install lazygit
And then call lazygit from within a git repository.

9) neovim neovim has been shipped in Debian since 2016, but upstream has been doing a lot of work to improve the experience out-of-the-box in the last couple of years. If you're a neovim poweruser, you're likely not installing it from the official repositories, but for those that are, Debian 13 comes with version 0.10.4, which brings the following improvements compared to the version in Debian 12:
  • Treesitter support for C, Lua, Markdown, with the possibility of adding any other languages as needed;
  • Better spellchecking due to treesitter integration (spellsitter);
  • Mouse support enabled by default;
  • Commenting support out-of-the-box; Check :h commenting for details, but the tl;dr is that you can use gcc to comment the current line and gc to comment the current selection.
  • OSC52 support. Especially handy for those using neovim over an ssh connection, this protocol lets you copy something from within the neovim process into the clipboard of the machine you're using to connect through ssh. In other words, you can copy from neovim running in a host over ssh and paste it in the "outside" machine.

10) [Bonus] Running old Debian releases The bonus tip is not specific to the Debian 13 release, but something I've recently learned in the #debian-devel IRC channel. Did you know there are usable container images for all past Debian releases? I'm not talking "past" as in "some of the older releases", I'm talking past as in "literally every Debian release, including the very first one". Tianon Gravi "tianon" is the Debian Developer responsible for making this happen, kudos to him! There's a small gotcha that the releases Buzz (1.1) and Rex (1.2) require a 32-bit host, otherwise you will get the error Out of virtual memory!, but starting with Bo (1.3) all should work in amd64/arm64. Try it out: 
sudo apt install podman

podman run -it docker.io/debian/eol:bo
Don't be surprised when noticing that apt/apt-get is not available inside the container, that's because apt first appeared in Debian Slink (2.1).

Changes since publication

2025-08-30
  • Mention that Arch also enabled HTTP/3.

Samuel Henrique: Debian 13: My list of exciting new features

A bunch of screenshots overlaid on top of each other showing different tools: lazygit, gnome settings, gnome system monitor, powerline-go, and the wcurl logo, the text at the top says 'Debian 13: My list of exciting new features', and there's a Debian logo in the middle of image

Beyond Debian: Useful for other distros too Every two years Debian releases a new major version of its Stable series, meaning the differences between consecutive Debian Stable releases represent two years of new developments both in Debian as an organization and its native packages, but also in all other packages which are also shipped by other distributions (which are getting into this new Stable release). If you're not paying close attention to everything that's going on all the time in the Linux world, you miss a lot of the nice new features and tools. It's common for people to only realize there's a cool new trick available only years after it was first introduced. Given these considerations, the tips that I'm describing will eventually be available in whatever other distribution you use, be it because it's a Debian derivative or because it just got the same feature from the upstream project. I'm not going to list "passive" features (as good as they can be), the focus here is on new features that might change how you configure and use your machine, with a mix between productivity and performance.

Debian 13 - Trixie I have been a Debian Testing user for longer than 10 years now (and I recommend it for non-server users), so I'm not usually keeping track of all the cool features arriving in the new Stable releases because I'm continuously receiving them through the Debian Testing rolling release. Nonetheless, as a Debian Developer I'm in a good position to point out the ones I can remember. I would also like other Debian Developers to do the same as I'm sure I would learn something new. The Debian 13 release notes contain a "What's new" section , which lists the first two items here and a few other things, in other words, take my list as an addition to the release notes. Debian 13 was released on 2025-08-09, and these are nice things you shouldn't miss in the new release, with a bonus one not tied to the Debian 13 release.

1) wcurl wcurl logo Have you ever had to download a file from your terminal using curl and didn't remember the parameters needed? I did. Nowadays you can use wcurl; "a command line tool which lets you download URLs without having to remember any parameters." Simply call wcurl with one or more URLs as parameters and it will download all of them in parallel, performing retries, choosing the correct output file name, following redirects, and more. Try it out: 
wcurl example.com
wcurl comes installed as part of the curl package on Debian 13 and in any other distribution you can imagine, starting with curl 8.14.0. I've written more about wcurl in its release announcement and I've done a lightning talk presentation in DebConf24, which is linked in the release announcement.

2) HTTP/3 support in curl Debian has become the first stable Linux distribution to ship curl with support for HTTP/3. I've written about this in July 2024, when we first enabled it. Note that we first switched the curl CLI to GnuTLS, but then ended up releasing the curl CLI linked with OpenSSL (as support arrived later). Debian was the first Linux distro to enable it in the default build of the curl package, but Gentoo enabled it a few weeks earlier in their non-default flavor of the package, kudos to them! HTTP/3 is not used by default by the curl CLI, you have to enable it with --http3 or --http3-only. Try it out: 
curl --http3 https://www.example.org
curl --http3-only https://www.example.org

3) systemd soft-reboot Starting with systemd v254, there's a new soft-reboot option, it's an userspace-only reboot, much faster than a full reboot if you don't need to reboot the kernel. You can read the announcement from the systemd v254 GitHub release Try it out: 
# This will reboot your machine!
systemctl soft-reboot

4) apt --update Are you tired of being required to run sudo apt update just before sudo apt upgrade or sudo apt install $PACKAGE? So am I! The new --update option lets you do both things in a single command: 
sudo apt --update upgrade
sudo apt --update install $PACKAGE
I love this, but it's still not yet where it should be, fingers crossed for a simple apt upgrade to behave like other package managers by updating its cache as part of the task, maybe in Debian 14? Try it out: 
sudo apt upgrade --update
# The order doesn't matter
sudo apt --update upgrade
This is especially handy for container usage, where you have to update the apt cache before installing anything, for example: 
podman run debian:stable bin/bash -c 'apt install --update -y curl'

5) powerline-go powerline-go is a powerline-style prompt written in Golang, so it's much more performant than its Python alternative powerline. powerline-style prompts are quite useful to show things like the current status of the git repo in your working directory, exit code of the previous command, presence of jobs in the background, whether or not you're in an ssh session, and more. A screenshot of a terminal with powerline-go enabled, showing how the PS1 changes inside a git repository and when the last command fails Try it out: 
sudo apt install powerline-go
Then add this to your .bashrc: 
function _update_ps1()  
    PS1="$(/usr/bin/powerline-go -error $? -jobs $(jobs -p   wc -l))"

    # Uncomment the following line to automatically clear errors after showing
    # them once. This not only clears the error for powerline-go, but also for
    # everything else you run in that shell. Don't enable this if you're not
    # sure this is what you want.

    #set "?"
 

if [ "$TERM" != "linux" ] && [ -f "/usr/bin/powerline-go" ]; then
    PROMPT_COMMAND="_update_ps1; $PROMPT_COMMAND"
fi
Or this to .zshrc: 
function powerline_precmd()  
    PS1="$(/usr/bin/powerline-go -error $? -jobs $ $ (%):%j :-0 )"

    # Uncomment the following line to automatically clear errors after showing
    # them once. This not only clears the error for powerline-go, but also for
    # everything else you run in that shell. Don't enable this if you're not
    # sure this is what you want.

    #set "?"
If you'd like to have your prompt start in a newline, like I have in the screenshot above, you just need to set -newline in the powerline-go invocation in your .bashrc/.zshrc.

6) Gnome System Monitor Extension Tips number 6 and 7 are for Gnome users. Gnome is now shipping a system monitor extension which lets you get a glance of the current load of your machine from the top bar. Screenshot of the top bar of Gnome with the system monitor extension enabled, showing the load of: CPU, memory, network and disk I've found this quite useful for machines where I'm required to install third-party monitoring software that tends to randomly consume more resources than it should. If I feel like my machine is struggling, I can quickly glance at its load to verify if it's getting overloaded by some process. The extension is not as complete as system-monitor-next, not showing temperatures or histograms, but at least it's officially part of Gnome, easy to install and supported by them. Try it out: 
sudo apt install gnome-system-monitor gnome-shell-extension-manager
And then enable the extension from the "Extension Manager" application.

7) Gnome setting for battery charging profile After having to learn more about batteries in order to get into FPV drones, I've come to have a bigger appreciation for solutions that minimize the inevitable loss of capacity that accrues over time. There's now a "Battery Charging" setting (under the "Power") section which lets you choose between two different profiles: "Maximize Charge" and "Preserve Battery Health". A screenshot of the Gnome settings for Power showing the options for Battery Charging On supported laptops, this setting is an easy way to set thresholds for when charging should start and stop, just like you could do it with the tlp package, but now from the Gnome settings. To increase the longevity of my laptop battery, I always keep it at "Preserve Battery Health" unless I'm traveling. What I would like to see next is support for choosing different "Power Modes" based on whether the laptop is plugged-in, and based on the battery charge percentage. There's a GNOME issue tracking this feature, but there's some pushback on whether this is the right thing to expose to users. In the meantime, there are some workarounds mentioned in that issue which people who really want this feature can follow. If you would like to learn more about batteries; Battery University is a great starting point, besides getting into FPV drones and being forced to handle batteries without a Battery Management System (BMS). And if by any chance this sparks your interest in FPV drones, Joshua Bardwell's YouTube channel is a great resource: @JoshuaBardwell.

8) Lazygit Emacs users are already familiar with the legendary magit; a terminal-based UI for git. Lazygit is an alternative for non-emacs users, you can integrate it with neovim or just use it directly. I'm still playing with lazygit and haven't integrated it into my workflows, but so far it has been a pleasant experience. Screenshot of lazygit from the Debian curl repository, showing a selected commit and its diff, besides the other things from the lazygit UI You should check out the demos from the lazygit GitHub page. Try it out: 
sudo apt install lazygit
And then call lazygit from within a git repository.

9) neovim neovim has been shipped in Debian since 2016, but upstream has been doing a lot of work to improve the experience out-of-the-box in the last couple of years. If you're a neovim poweruser, you're likely not installing it from the official repositories, but for those that are, Debian 13 comes with version 0.10.4, which brings the following improvements compared to the version in Debian 12:
  • Treesitter support for C, Lua, Markdown, with the possibility of adding any other languages as needed;
  • Better spellchecking due to treesitter integration (spellsitter);
  • Mouse support enabled by default;
  • Commenting support out-of-the-box; Check :h commenting for details, but the tl;dr is that you can use gcc to comment the current line and gc to comment the current selection.
  • OSC52 support. Especially handy for those using neovim over an ssh connection, this protocol lets you copy something from within the neovim process into the clipboard of the machine you're using to connect through ssh. In other words, you can copy from neovim running in a host over ssh and paste it in the "outside" machine.

10) [Bonus] Running old Debian releases The bonus tip is not specific to the Debian 13 release, but something I've recently learned in the #debian-devel IRC channel. Did you know there are usable container images for all past Debian releases? I'm not talking "past" as in "some of the older releases", I'm talking past as in "literally every Debian release, including the very first one". Tianon Gravi "tianon" is the Debian Developer responsible for making this happen, kudos to him! There's a small gotcha that the releases Buzz (1.1) and Rex (1.2) require a 32-bit host, otherwise you will get the error Out of virtual memory!, but starting with Bo (1.3) all should work in amd64/arm64. Try it out: 
sudo apt install podman

podman run -it docker.io/debian/eol:bo
Don't be surprised when noticing that apt/apt-get is not available inside the container, that's because apt first appeared in Debian Slink (2.1).

27 August 2025

Matthew Palmer: StrongBox: Simple, Safe Data Encryption for Rust

Some time ago, I wanted to encrypt a bunch of data in an application I was writing in Rust, mostly to be stored in a database, but also session cookies and sensitive configuration variables. Since Rust is widely known as a secure-yet-high-performance programming language, I was expecting that there would be a widely-used crate that gave me a secure, high-level interface to strong, safe cryptography. Imagine my surprise when I discovered that just didn t seem to exist. Don t get me wrong: Rust is replete with fast, secure, battle-tested cryptographic primitives. The RustCrypto group provides all manner of robust, widely-used crates for all manner of cryptography-related purposes. They re the essential building blocks for practical cryptosystems, but using them directly in an application is somewhat akin to building a car from individual atoms of iron and carbon. So I wrote my own high-level data encryption library, called it StrongBox, and have been happily encrypting and decrypting data ever since.

Cryptography So Simple Even I Can t Get It Wrong The core of StrongBox is the StrongBox trait, which has only two methods: encrypt and decrypt, each of which takes just two arguments. The first argument is the plaintext (for encrypt) or the ciphertext (for decrypt) to work on. The second argument is the encryption context, for use as Authenticated Additional Data, an important part of many uses of encryption. There s essentially no configuration or parameters to get wrong. You can t choose the encryption algorithm, or block cipher mode, and you don t have to worry about generating a secure nonce. You create a StrongBox with a key, and then you call encrypt and decrypt. That s it.

Practical Cryptographic Affordances Ok, ok that s not quite it. Because StrongBox is even easier to use than what I ve described, thanks to the companion crate, StructBox. When I started using StrongBox in the wild , it quickly became clear that what I almost always wanted to encrypt in my application wasn t some ethereal plaintext . I wanted to encrypt things, specifically structs (and enums). So, through the magic of Rust derive macros, I built StructBox, which provides encrypt and decrypt operations on any Serde-able type. Given that using Serde encoders can be a bit fiddly to use, it s virtually easier to get an encrypted, serialized struct than it is to get a plaintext serialized struct.

Key Problems in Cryptography The thing about cryptography is that it largely turns all data security problems into key management problems. All the fancy cryptographic wonkery is for naught if you don t manage the encryption keys well. So, most of the fancy business in StrongBox isn t the encryption and decryption, but instead solving problems around key management.

Different Keys for Different Purposes Using the same key for all of your cryptographic needs is generally considered a really bad idea. It opens up all manner of risks, that are easily avoided if you use different keys for different things. However, having to maintain a big pile of different keys is a nightmare, so nobody s going to do that. Enter: key derivation. Create one safe, secure root key, and then use a key derivation function to spawn as many other keys as you need. Different keys for each database column, another one to encrypt cookies, and so on. StrongBox supports this through the StemStrongBox type. You ll typically start off by creating a StemStrongBox with the root key, and then derive whatever other StrongBoxes you need, for encrypting and decrypting different kinds of data.

You Spin Me Round Sometimes, keys need to be rotated. Whether that s because you actually know (or even have reason to suspect) someone has gotten the key, or just because you re being appropriately paranoid, sometimes key rotation has to happen. As someone who has had to rotate keys in situations where such an eventuality was not planned for, I can say with some degree of authority: it absolutely sucks to have to do an emergency key rotation in a system that isn t built to make that easy. That s why StrongBox natively supports key rotation. Every StrongBox takes one encryption key, and an arbitrary number of decryption keys, and will automatically use the correct key to decrypt ciphertexts.

Will You Still Decrypt Me, Tomorrow? In addition to manual key rotation, StrongBox also supports time-based key rotation with the RotatingStrongBox type. This comes in handy when you re encrypting a lot of ephemeral data, like cookies (or server-side session data). It provides a way to automatically expire old data, and prevents attacks that become practical when large amounts of data are encrypted using a single key.

Invasion of the Invisible Salamanders! I mostly mention this just because I love the name, but there is a kind of attack possible in common AEAD modes called the invisible salamanders attack. StrongBox implements mitigations against this, by committing to the key being used so that an attacker can t forge a ciphertext that decrypts validly to different plaintexts when using different keys. This is why I love cryptography: everything sounds like absolute goddamn magic.

Call Me Crazy, Support Me Maybe? If you re coding in Rust (which you probably should be), encrypting your stored data (which you definitely should be), and StrongBox makes your life easier (which it really will), you can show your appreciation for my work by contributing to my open source code-fund. Simply by shouting me a refreshing beverage, you ll be helping me out, and helping to grow the software commons. Alternately, if you re looking for someone to Speak Rust to Computers on a professional basis, I m available for contracts or full-time remote positions.

21 August 2025

Matthew Palmer: Progress on my open source funding experiment

When I recently announced that I was starting an open source crowd-funding experiment, I wasn t sure what would happen. Perhaps there d be radio silence, or a huge out-pouring of interest from people who wanted to see more open source code in the world. What s happened so far has been interesting. I chose to focus on action-validator because it s got a number of open feature requests, and it solves a common problem that people have. The thing is, I ve developed and released a lot of open source over the multiple decades I ve been noodling around with computers. Much of that has been of use to many people, the overwhelming majority of whom I will never, ever meet, hear from, or even know that I ve helped them out. One person, however, I do know about a generous soul named Andy, who (as far as I know) doesn t use action-validator, but who does use another tool I wrote some years ago: lvmsync. It s somewhat niche, essentially rsync for LVM-backed block devices , so I m slightly surprised that it s my most-starred repository, at nearly 400(!) stars. Andy is one of the people who finds it useful, and he was kind enough to reach out and offer a contribution in thanks for lvmsync existing. In the spirit of my open source code-fund, I applied Andy s contribution to the general pool, and as a result have just released action-validator v0.8.0, which supports a new --rootdir command-line option, fixing action-validator issue #54. Everyone who uses --rootdir in their action-validator runs has Andy to thank, and I thank him too. This is, of course, still early days in my experiment. You can be like Andy, and make the open source world a better place, by contributing to my code-fund, and you can get your name up in lights, too. Whether you re an action-validator user, have gotten utility from any of the other things I ve written, or just want to see more open source code in the world, your contribution is greatly appreciated.

3 August 2025

Aigars Mahinovs: Debconf 25 photos

Debconf 25 photos Debconf 25 came to the end in Brest, France this year a couple weeks ago. This has been a very different and unusually interesting Debconf. For me it was for two, related reasons: for one the conference was close enough in Western Europe that I could simply drive there with a car (which reminds me that I should make a blog post about the BMW i5, before I am done with it at the end of this year) and for the other - the conference is close enough to Western Europe that many other Debian developers could join this year who have not been seen at the event for many years. Being able to arrive early, decompress and spend extra time looking around the place made the event itself even more enjoyable than usual. The French cuisine, especially in its Breton expression, has been a very welcome treat. Even if there were some rough patches with the food selection, amount, or waiting, it was still a great experience. I specifically want to say a big thank you to the organisers for everything, but very explicitly for planning all the talk/BOF rooms in the same building and almost on the same floor. It saved me a lot of footwork, but also for other participants the short walks between the talks made it possible to always have a few minutes to talk to people or grab a croissant before running to the next talk. IMHO we should come back to a tradition of organising Debconf in Europe every 2-3 years. This maximises one of the main goals of Debconf - bringing as many Debian Developers as possible together in one physical location. This works best when the location is actually close to large concentrations of existing developers. In other years, the other goal of Debconf can then take priority - recruiting new developers in new locations. However, these goals could both be achieved at the same time - there are plenty of locations in Europe and even in Western Europe that still have good potential for attracting new developers. Especially if we focus on organising the event on the campuses of some larger technically-oriented universities. This year was also very productive for me a lot of conversations with various people about all kinds of topics, especially technical packaging questions. It has been a long time since the very basic foundations of Debian packaging work have been so fundamentally refactored and modernized as in the past year. Tag2upload has become a catalyst for git-based packaging and for automated workflows via Salsa, and all of that feeds back into focusing on a few best-supported packaging workflows. There is still a bit of a documentation gap of a new contributor getting to these modern packaging workflows from the point where the New Maintainers Guide stops. In any case, next year Debconf will be happening in Santa Fe, Argentina. And the year after that it is all still open and in a close competition between Japan, Spain, Portugal, Brazil and .. El Salvador? Personally, I would love to travel to Japan (again), but Spain or Portugal would also be great locations to meet more European developers again. As for Santa Fe ... it is quite likely that I will not be able to make it there next year, for (planned) health reasons. I guess I should also write a new blog post about what it means to be a Debconf Photographer, so that someone else could do this as well, and also reduce the "bus factor" along the way. But before that - here is the main group photo from this year: DebConf 25 Group photo You can also see it on: You can also enjoy the rest of the photos: Additionally, check out photos from other people on GIT LFS and consider adding your own photos there as well. Other places I have updated with up-to-date information are these wiki pages: If you took part in the playing cards event, then check your photo in this folder and link to your favourite from your line in the playing card wiki

10 July 2025

Tianon Gravi: Yubi Whati? (YubiKeys, ECDSA, and X.509)

Off-and-on over the last several weeks, I've been spending time trying to learn/understand YubiKeys better, especially from the perspective of ECDSA and signing. I had a good mental model for how "slots" work (canonically referenced by their hexadecimal names such as 9C), but found that it had a gap related to "objects"; while closing that, I was annoyed that the main reference table for this gap lives primarily in either a PDF or inside several implementations, so I figured I should create the reference I want to see in the world, but that it would also be useful to write down some of my understanding for my own (and maybe others') future reference. So, to that end, I'm going to start with a bit ( ) of background information, with the heavy caveat that this only applies to "PIV" ("FIPS 201") usage of YubiKeys, and that I only actually care about ECDSA, although I've been reassured that it's the same for at least RSA (anything outside this is firmly Here Be Not Tianon; "gl hf dd"). (Incidentally, learning all this helped me actually appreciate the simplicity of cloud-based KMS solutions, which was an unexpected side effect. ) At a really high level, ECDSA is like many other (asymmetric) cryptographic solutions you've got a public key and a private key, the private key can be used to "sign" data (tiny amounts of data, in fact, like P-256 can only reasonably sign 256 bits of data, which is where cryptographic hashes like SHA256 come in as secure analogues for larger data in small bit sizes), and the public key can then be used to verify that the data was indeed signed by the private key, and only someone with the private key could've done so. There's some complex math and RNGs involved, but none of that's actually relevant to this post, so find that information elsewhere. Unfortunately, this is where things go off the rails: PIV is X.509 ("x509") heavy, and there's no X.509 in the na ve view of my use case. In a YubiKey (or any other PIV-signing-supporting smart card? do they actually have competitors in this specific niche? ), a given "slot" can hold one single private key. There are ~24 slots which can hold a private key and be used for signing, although "Slot 9c" is officially designated as the "Digital Signature" slot and is encouraged for signing purposes. One of the biggest gotchas is that with pure-PIV (and older YubiKey firmware ) the public key for a given slot is only available at the time the key is generated, and the whole point of the device in the first place is that the private key is never, ever available from it (all cryptographic operations happen inside the device), so if you don't save that public key when you first ask the device to generate a private key in a particular slot, the public key is lost forever (asterisk). 
$ # generate a new ECDSA P-256 key in "slot 9c" ("Digital Signature")
$ # WARNING: THIS WILL GLEEFULLY WIPE SLOT 9C WITHOUT PROMPTING
$ yubico-piv-tool --slot 9c --algorithm ECCP256 --action generate
-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEtGoWRGyjjUlJFXpu8BL6Rnx8jjKR
5+Mzl2Vepgor+k7N9q7ppOtSMWefjFVR0SEPmXqXINNsCi6LpLtNEigIRg==
-----END PUBLIC KEY-----
Successfully generated a new private key.
$ # this is the only time/place we (officially) get this public key
With that background, now let's get to the second aspect of "slots" and how X.509 fits. For every aforementioned slot, there is a corresponding "object" (read: place to store arbitrary data) which is corresponding only by convention. For all these "key" slots the (again, by convention) corresponding "object" is explicitly supposed to be an X.509 certificate (see also the PDF reference linked above). It turns out this is a useful and topical place to store that public key we need to keep handy! It's also an interesting place to shove additional details about what the key in a given slot is being used for, if that's your thing. Converting the raw public key into a (likely self-signed) X.509 certificate is an exercise for the reader, but if you want to follow the conventions, you need some way to convert a given "slot" to the corresponding "object", and that is the lookup table I wish existed in more forms. So, without further ado, here is the anti-climax:
Slot Object Description
0x9A 0x5FC105 X.509 Certificate for PIV Authentication
0x9E 0x5FC101 X.509 Certificate for Card Authentication
0x9C 0x5FC10A X.509 Certificate for Digital Signature
0x9D 0x5FC10B X.509 Certificate for Key Management
0x82 0x5FC10D Retired X.509 Certificate for Key Management 1
0x83 0x5FC10E Retired X.509 Certificate for Key Management 2
0x84 0x5FC10F Retired X.509 Certificate for Key Management 3
0x85 0x5FC110 Retired X.509 Certificate for Key Management 4
0x86 0x5FC111 Retired X.509 Certificate for Key Management 5
0x87 0x5FC112 Retired X.509 Certificate for Key Management 6
0x88 0x5FC113 Retired X.509 Certificate for Key Management 7
0x89 0x5FC114 Retired X.509 Certificate for Key Management 8
0x8A 0x5FC115 Retired X.509 Certificate for Key Management 9
0x8B 0x5FC116 Retired X.509 Certificate for Key Management 10
0x8C 0x5FC117 Retired X.509 Certificate for Key Management 11
0x8D 0x5FC118 Retired X.509 Certificate for Key Management 12
0x8E 0x5FC119 Retired X.509 Certificate for Key Management 13
0x8F 0x5FC11A Retired X.509 Certificate for Key Management 14
0x90 0x5FC11B Retired X.509 Certificate for Key Management 15
0x91 0x5FC11C Retired X.509 Certificate for Key Management 16
0x92 0x5FC11D Retired X.509 Certificate for Key Management 17
0x93 0x5FC11E Retired X.509 Certificate for Key Management 18
0x94 0x5FC11F Retired X.509 Certificate for Key Management 19
0x95 0x5FC120 Retired X.509 Certificate for Key Management 20
See also "piv-objects.json" for a machine-readable copy of this data. (Major thanks to paultag and jon gzip johnson for helping me learn and generally putting up with me, but especially dealing with my live-stream-of-thoughts while I stumble through the dark. )

4 July 2025

Russell Coker: Function Keys

For at least 12 years laptops have been defaulting to not having the traditional PC 101 key keyboard function key functionality and instead have had other functions like controlling the volume and have had a key labelled Fn to toggle the functions. It s been a BIOS option to control whether traditional function keys or controls for volume etc are the default and for at least 12 years I ve configured all my laptops to have the traditional function keys as the default. Recently I ve been working in corporate IT and having exposure to many laptops with the default BIOS settings for those keys to change volume etc and no reasonable option for addressing it. This has made me reconsider the options for configuring these things. Here s a page listing the standard uses of function keys [1]. Here is a summary of the relevant part of that page: The keys F1, F3, F4, F7, F9, F10, and F12 don t get much use for me and for the people I observe. The F2 and F8 keys aren t useful in most programs, F6 is only really used in web browsers but the web browser counts as most programs nowadays. Here s the description of Thinkpad Fn keys [2]. I use Thinkpads for fun and Dell laptops for work, so it would be nice if they both worked in similar ways but of course they don t. Dell doesn t document how their Fn keys are laid out, but the relevant bit is that F1 to F4 are the same as on Thinkpads which is convenient as they are the ones that are likely to be commonly used and needed in a hurry. I have used the KDE settings on my Thinkpad to map the function F1 to F3 keys to the Fn equivalents which are F1 to mute-audio, F2 for vol-down, and F3 for vol-up to allow using them without holding down the Fn key while having other function keys such as F5 and F6 have their usual GUI functionality. Now I have to could train myself to use F8 in situations where I usually use F2, at least when using a laptop. The only other Fn combinations I use are F5 and F6 for controlling screen brightness, but that s not something I use much. It s annoying that the laptop manufacturers forced me to this. Having a Fn key to get extra functions and not need 101+ keys on a laptop size device is a reasonable design choice. But they could have done away with the PrintScreen key to make space for something else. Also for Thinkpads a touch pad is something that could obviously be removed to gain some extra space as the Trackpoint does all that s needed in that regard.
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27 May 2025

Russell Coker: Leaf ZE1

I ve just got a second hand Nissan LEAF. It s not nearly as luxurious as the Genesis EV that I test drove [1]. It s also just over 5 years old so it s not as slick as the MG4 I test drove [2]. But the going rate for a LEAF of that age is $17,000 vs $35,000 or more for a new MG4 or $130,000+ for a Genesis. At this time the LEAF is the only EV in Australia that s available on the second hand market in quantity. Apparently the cheapest new EV in Australia is a Great Wall one which is $32,000 and which had a wait list last time I checked, so $17,000 is a decent price if you want an electric car and aren t interested in paying the price of a new car. Starting the Car One thing I don t like about most recent cars (petrol as well as electric) is that they needlessly break traditions of car design. Inserting a key and turning it clockwise to start a car is a long standing tradition that shouldn t be broken without a good reason. With the use of traditional keys you know that when a car has the key removed it can t be operated, there s no situation of the person with the key walking away and leaving the car driveable and there s no possibility of the owner driving somewhere without the key and then being unable to start it. To start a LEAF you have to have the key fob device in range, hold down the brake pedal, and then press the power button. To turn on accessories you do the same but without holding down the brake pedal. They also have patterns of pushes, push twice to turn it on, push three times to turn it off. This is all a lot easier with a key where you can just rotate it as many clicks as needed. The change of car design for the key means that no physical contact is needed to unlock the car. If someone stands by a car fiddling with the door lock it will get noticed which deters certain types of crime. If a potential thief can sit in a nearby car to try attack methods and only walk to the target vehicle once it s unlocked it makes the crime a lot easier. Even if the electronic key is as secure as a physical key allowing attempts to unlock remotely weakens security. Reports on forums suggest that the electronic key is vulnerable to replay attacks. I guess I just have to hope that as car thieves typically get less than 10% of the value of a car it s just not worth their effort to steal a $17,000 car. Unlocking doors remotely is a common feature that s been around for a while but starting a car without a key being physically inserted is a new thing. Other Features The headlights turn on automatically when the car thinks that the level of ambient light warrants it. There is an option to override this to turn on lights but no option to force the lights to be off. So if you have your car in the on state while parked the headlights will be on even if you are parked and listening to the radio. The LEAF has a bunch of luxury features which seem a bit ridiculous like seat warmers. It also has a heated steering wheel which has turned out to be a good option for me as I have problems with my hands getting cold. According to the My Nissan LEAF Forum the seat warmer uses a maximum of 50W per seat while the car heater uses a minimum of 250W [3]. So if there are one or two people in the car then significantly less power is used by just heating the seats and also keeping the car air cool reduces window fog. The Bluetooth audio support works well. I ve done hands free calls and used it for playing music from my phone. This is the first car I ve owned with Bluetooth support. It also has line-in which might have had some use in 2019 but is becoming increasingly useless as phones with Bluetooth become more popular. It has support for two devices connecting via Bluetooth at the same time which could be handy if you wanted to watch movies on a laptop or tablet while waiting for someone. The LEAF has some of the newer safety features, it tracks lane markers and notifies the driver via beeps and vibration if they stray from their lane. It also tries to read speed limit signs and display the last observed speed limit on the dash display. It also has a skid alert which in my experience goes off under hard acceleration when it s not skidding but doesn t go off if you lose grip when cornering. The features for detecting changing lanes when close to other cars and for emergency braking when another car is partly in the lane (even if moving out of the lane) don t seem well tuned for Australian driving, the common trend on Australian roads is lawful-evil to use DND terminology. Range My most recent driving was just over 2 hours driving with a distance of a bit over 100Km which took the battery from 62% to 14%. So it looks like I can drive a bit over 200Km at an average speed of 50Km/h. I have been unable to find out the battery size for my car, my model will have either a 40KWh or 62KWh battery. Google results say it should be printed on the B pillar (it s not) and that it can be deduced from the VIN (it can t). I m guessing that my car is the cheaper option which is supposed to do 240Km when new which means that a bit over 200Km at an average speed of 50Km/h when 6yo is about what s expected. If it has the larger battery designed to do 340Km then doing 200Km in real use would be rather disappointing. Assuming the battery is 40KWh that means it s 5Km/KWh or 10KW average for the duration. That means that the 250W or so used by the car heater should only make a about 2% difference to range which is something that a human won t usually notice. If I was to drive to another state I d definitely avoid using the heater or airconditioner as an extra 4km could really matter when trying to find a place to charge when you aren t familiar with the area. It s also widely reported that the LEAF is less efficient at highway speeds which is an extra difficulty for that. It seems that the LEAF just isn t designed for interstate driving in Australia, it would be fine for driving between provinces of the Netherlands as it s difficult to drive for 200km without leaving that country. Driving 700km to another city in a car with 200km range would mean charging 3 times along the way, that s 2 hours of charging time when using fast chargers. This isn t a problem at all as the average household in Australia has 1.8 cars and the battery electric vehicles only comprise 6.3% of the market. So if a household had a LEAF and a Prius they could just use the Prius for interstate driving. A recent Prius could drive from Melbourne to Canberra or Adelaide without refuelling on the way. If I was driving to another state a couple of times a year I could rent an old fashioned car to do that and still be saving money when compared to buying petrol all the time. Running Cost Currently I m paying about $0.28 per KWh for electricity, it s reported that the efficiency of charging a LEAF is as low as 83% with the best efficiency when fast charging. I don t own the fast charge hardware and don t plan to install it as that would require getting a replacement of the connection to my home from the street, a new switchboard, and other expenses. So I expect I ll be getting 83% efficiency when charging which means 48KWh for 200KM or 96KWH for the equivalent of a $110 tank of petrol. At $0.28/KWh it will cost $26 for the same amount of driving as $110 of petrol. I also anticipate saving money on service as there s no need for engine oil changes and all the other maintenance of a petrol engine and regenerative braking will reduce the incidence of brake pad replacement. I expect to save over $1100 per annum on using electricity instead of petrol even if I pay the full rate. But if I charge my car in the middle of the day when there is over supply and I don t get paid for feeding electricity from my solar panels into the grid (as is common nowadays) it could be almost free to charge the car and I could save about $1500 on fuel. Comfort Electric cars are much quieter than cars with petrol or Diesel engines which is a major luxury feature. This car is also significantly newer than any other car I ve driven much so it has features like Bluetooth audio which weren t in other cars I ve driven. When doing 100Km/h I can hear a lot of noise from the airflow, part of that would be due to the LEAF not having the extreme streamlining features that are associated with Teslas (such as retracting door handles) and part of that would be due to the car being older and the door seals not being as good as they were when new. It s still a very quiet car with a very smooth ride. It would be nice if they used the quality of seals and soundproofing that VW uses in the Passat but I guess the car would be heavier and have a shorter range if they did that. This car has less space for the driver than any other car I ve driven (with the possible exception of a 1989 Ford Laser AKA Mazda 323). The front seats have less space than the Prius. Also the batteries seem to be under the front seats so there s a bulge in the floor going slightly in front of the front seats when they are moved back which gives less space for the front passenger to move their legs and less space for the driver when sitting in a parked car. There are a selection of electric cars from MG, BYD, and Great Wall that have more space in the front seats, if those cars were on the second hand market I might have made a different choice but a second hand LEAF is the only option for a cheap electric car in Australia now. The heated steering wheel and heated seats took a bit of getting used to but I have come to appreciate the steering wheel and the heated seats are a good way of extending the range of the car. Misc Notes The LEAF is a fun car to drive and being quiet is a luxury feature, it s no different to other EVs in this regard. It isn t nearly as fast as a Tesla, but is faster than most cars actually drive on the road. When I was looking into buying a LEAF from one of the car sales sites I was looking at models less than 5 years old. But the ZR1 series went from 2017 to 2023 so there s probably not much difference between a 2019 model and a 2021 model but there is a significant price difference. I didn t deliberately choose a 2019 car, it was what a relative was selling at a time when I needed a new car. But knowing what I know now I d probably look at that age of LEAF if choosing from the car sales sites. Problems When I turn the car off the side mirrors fold in but when I turn it on they usually don t automatically unfold if I have anything connected to the cigarette lighter power port. This is a well known problem and documented on forums. This is something that Nissan really should have tested before release because phone chargers that connect to the car cigarette lighter port have been common for at least 6 years before my car was manufactured and at least 4 years before the ZE1 model was released. The built in USB port doesn t supply enough power to match the power use of a Galaxy Note 9 running Google maps and playing music through Bluetooth. On it s own this isn t a big deal but combined with the mirror issue of using a charger in the cigarette lighter port it s a problem. The cover over the charging ports doesn t seem to lock easily enough, I had it come open when doing 100Km/h on a freeway. This wasn t a big deal but as the cover opens in a suicide-door manner at a higher speed it could have broken off. The word is that LEAF service in Australia is not done well. Why do you need regular service of an electric car anyway? For petrol and Diesel cars it s engine oil replacement that makes it necessary to have regular service. Surely you can just drive it until either the brakes squeak or the tires seem worn. I have been having problems charging, sometimes it will charge from ~20% to 100% in under 24 hours, sometimes in 14+ hours it only gets to 30%. Conclusion This is a good car and the going price on them is low. I generally recommend them as long as you aren t really big and aren t too worried about the poor security. It s a fun car to drive even with a few annoying things like the mirrors not automatically extending on start. The older ones like this are cheap enough that they should be able to cover the entire purchase cost in 10 years by the savings from not buying petrol even if you don t drive a lot. With a petrol car I use about 13 tanks of petrol a year so my driving is about half the average for Australia. Some people could cover the purchase price of a second hand leaf in under 5 years.
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17 May 2025

Andrew Cater: 20250517 - Debian point release - Bookworm 12.11 today

In Cottenham with Andy and the usual suspects. The point release update files are already on the servers - anyone can do an "apt-get update ; apt-get dist-upgrade" and update any running machine. This machine has just been upgraded and "just worked".

Here to do release testing for the images that we will end up publishing later in the day.Expecting one more of us to turn up a bit later. Team will be working on IRC on #debian-cd


5 April 2025

Russell Coker: More About the HP ML110 Gen9 and z640

In May 2021 I bought a ML110 Gen9 to use as a deskside workstation [1]. I started writing this post in April 2022 when it had been my main workstation for almost a year. While this post was in a draft state in Feb 2023 I upgraded it to an 18 core E5-2696 v3 CPU [2]. It s now March 2025 and I have replaced it. Hardware Issues My previous state with this was not having adequate cooling to allow it to boot and not having a PCIe power cable for a video card. As an experiment I connected the CPU fan to the PCIe fan power and discovered that all power and monitoring wires for the CPU and PCIe fans are identical. This allowed me to buy a CPU fan which was cheaper ($26.09 including postage) and easier to obtain than a PCIe fan (presumably due to CPU fans being more commonly used and manufactured in larger quantities). I had to be creative in attaching the CPU fan as it s cable wasn t long enough to reach the usual location for a PCIe fan. The PCIe fan also required a baffle to direct the air to the right place which annoyingly HP apparently doesn t ship with the low end servers, so I made one from a Corn Flakes packet and duct tape. The Wikipedia page listing AMD GPUs lists many newer ones that draw less than 80W and don t need a PCIe power cable. I ordered a Radeon RX560 4G video card which cost $246.75. It only uses 8 lanes of PCIe but that s enough for me, the only 3D game I play is Warzone 2100 which works well at 4K resolution on that card. It would be really annoying if I had to just spend $246.75 to get the system working, but I had another system in need of a better video card which had a PCIe power cable so the effective cost was small. I think of it as upgrading 2 systems for $123 each. The operation of the PCIe video card was a little different than non-server systems. The built in VGA card displayed the hardware status at the start and then kept displaying that after the system had transitioned to PCIe video. This could be handy in some situations if you know what it s doing but was confusing initially. Booting One insidious problem is that when booting in legacy mode the boot process takes an unreasonably long time and often hangs, the UEFI implementation on this system seems much more reliable and also supports booting from NVMe. Even with UEFI the boot process on this system was slow. Also the early stage of the power on process involves fans being off and the power light flickering which leads you to think that it s not booting and needs to have the power button pressed again which turns it off. The Dell power on sequence of turning most LEDs on and instantly running the fans at high speed leaves no room for misunderstanding. This is also something that companies making electric cars could address. When turning on a machine you should never be left wondering if it is actually on. Noise This was always a noisy system. When I upgraded the CPU from an 8 core with 85W typical TDP to an 18 core with 145W typical TDP it became even louder. Then over time as dust accumulated inside the machine it became louder still until it was annoyingly loud outside the room when all 18 cores were busy. Replacement I recently blogged about options for getting 8K video to work on Linux [3]. This requires PCIe power which the z640s have (all the ones I have seen have it I don t know if all that HP made have it) and which the cheaper models in the ML-110 line don t have. Since then I have ordered an Intel Arc card which apparently has 190W TDP. There are adaptors to provide PCIe power from SATA or SAS power which I could have used, but having a E5-2696 v3 CPU that draws 145W [4] and a GPU that draws 190W [4] in a system with a 350W PSU doesn t seem viable. I replaced it with one of the HP z640 workstations I got in 2023 [5]. The current configuration of the z640 has 3*32G RDIMMs compared to the ML110 having 8*32G, going from 256G to 96G is a significant decrease but most tasks run well enough like that. A limitation of the z640 is that when run with a single CPU it only has 4 DIMM slots which gives a maximum of 512G if you get 128G LRDIMMs, but as all DDR4 DIMMs larger than 32G are unreasonably expensive at this time the practical limit is 128G (which costs about $120AU). In this case I have 96G because the system I m using has a motherboard problem which makes the fourth DIMM slot unusable. Currently my desire to get more than 96G of RAM is less than my desire to avoid swapping CPUs. At this time I m not certain that I will make my main workstation the one that talks to an 8K display. But I really want to keep my options open and there are other benefits. The z640 boots faster. It supports PCIe bifurcation (with a recent BIOS) so I now have 4 NVMe devices in a single PCIe slot. It is very quiet, the difference is shocking. I initially found it disconcertingly quiet. The biggest problem with the z640 is having only 4 DIMM sockets and the particular one I m using has a problem limiting it to 3. Another problem with the z640 when compared to the ML110 Gen9 is that it runs the RAM at 2133 while the ML110 runs it at 2400, that s a significant performance reduction. But the benefits outweigh the disadvantages. Conclusion I have no regrets about buying the ML-110. It was the only DDR4 ECC system that was in the price range I wanted at the time. If I knew that the z640 systems would run so quietly then I might have replaced it earlier. But it was only late last year that 32G DIMMs became affordable, before then I had 8*16G DIMMs to give 128G because I had some issues of programs running out of memory when I had less.
Related posts:
  1. HP ML110 Gen9 I ve just bought a HP ML110 Gen9 as a personal...
  2. T320 iDRAC Failure and new HP Z640 The Dell T320 Almost 2 years ago I made a...
  3. Video Decoding I ve had a saga of getting 4K monitors to work...

31 March 2025

Johannes Schauer Marin Rodrigues: TIL: OpenPGP Web Key Directory

Today I was looking for a way on how to best publish my OpenPGP key on my webserver. Surely, somebody came up with some sort of standard way for where to place that key, right? Turns out, they did: https://datatracker.ietf.org/doc/draft-koch-openpgp-webkey-service/ The TLDR summary is, that my key can now be found here: https://mister-muffin.de/.well-known/openpgpkey/hu/8yxgr5jjfok88r9um56kb44x9h4dyj7f Or be downloadable by just running: 
$ gpg --locate-key josch@mister-muffin.de
Where does the hash come from? It s the local part of my email (josch) hashed with sha1 and encoded in z-base32. That computation can be done by gpg: 
$ gpg --with-wkd-hash -k josch@mister-muffin.de   grep mister-muffin.de
[...]
8yxgr5jjfok88r9um56kb44x9h4dyj7f@mister-muffin.de
I exported the key that I put there using the following command: 
$ gpg --no-options --export --export-options export-minimal,export-clean \
    --export-filter keep-uid="uid = Johannes Schauer Marin Rodrigues <josch@mister-muffin.de>" \
    F83356BBE112B7462A41552F7D5D8C60CF4D3EB4
There is a handy validator for such setups that can be found here: https://www.webkeydirectory.com I had an interesting debugging experience when I tried to verify my setup in a fresh Debian chroot because I got this error message when I ran above command: 
gpg: directory '/root/.gnupg' created
gpg: keybox '/root/.gnupg/pubring.kbx' created
gpg: /root/.gnupg/trustdb.gpg: trustdb created
gpg: error retrieving 'josch@mister-muffin.de' via WKD: General error
gpg: error reading key: General error
That s not very descriptive Turns out, that I was missing the ca-certificates package. After installing it, everything worked as expected: 
$ gpg --locate-key josch@mister-muffin.de
gpg: key 7D5D8C60CF4D3EB4: public key "Johannes Schauer Marin Rodrigues <josch@mister-muffin.de>" imported
gpg: Total number processed: 1
gpg:               imported: 1
pub   rsa4096 2013-07-04 [SC]
      F83356BBE112B7462A41552F7D5D8C60CF4D3EB4
uid           [ unknown] Johannes Schauer Marin Rodrigues <josch@mister-muffin.de>
sub   rsa4096 2013-07-04 [E]
sub   rsa4096 2013-07-04 [S]
sub   rsa4096 2023-07-08 [S]

19 March 2025

Mark Brown: Seoul Trail revamp

I regularly visit Seoul, and for the last couple of years I&aposve been doing segments from the Seoul Trail, a series of walks that add up to a 150km circuit around the outskirts of Seoul. If you like hiking I recommend it, it&aposs mostly through the hills and wooded areas surrounding the city or parks within the city and the bits I&aposve done thus far have mostly been very enjoyable. Everything is generally well signposted and easy to follow, with varying degrees of difficulty from completely flat paved roads to very hilly trails.The trail had been divided into eight segments but just after I last visited the trail was reorganised into 21 smaller ones. This was very sensible, the original segments mostly being about 10-20km and taking 3-6 hours (with the notable exception of section 8, which was 36km) which can be a bit much (especially that section 8, or section 1 which had about 1km of ascent in it overall). It does complicate matters if you&aposre trying to keep track of what you&aposve done already though so I&aposve put together a quick table:
OriginalRevised
11-3
24-5
36-8
49-10
511-12
613-14
715-16
817-21
This is all straightforward, the original segments had all been arranged to start and stop at metro stations (which I think explains the length of 8, the metro network is thin around Bukhansan what with it being an actual mountain) and the new segments are all straight subdivisions, but it&aposs handy to have it written down and I figured other people might find it useful.

Next.