Search Results: "Philipp Kern"

23 August 2020

Philipp Kern: Self-service buildd givebacks now use Salsa auth

As client certificates are on the way out and Debian's SSO solution is effectively not maintained any longer, I switched self-service buildd givebacks over to Salsa authentication. It lives again at https://buildd.debian.org/auth/giveback.cgi. For authorization you still need to be in the "debian" group for now, i.e. be a regular Debian member.For convenience the package status web interface now features an additional column "Actions" with generated "giveback" links.Please remember to file bugs if you give builds back because of flakiness of the package rather than the infrastructure and resist the temptation to use this excessively to let your package migrate. We do not want to end up with packages that require multiple givebacks to actually build in stable, as that would hold up both security and stable updates needlessly and complicate development.

29 December 2016

Philipp Kern: Automating the installation of Debian on z/VM instances

I got tired of manually fetching installation images via either FTP or by manually transferring files to z/VM to test s390x installs. Hence it was about time to automate it. Originally I wanted to instrument an installation via vmcp from another instance on the same host but I figured that I cannot really rely on a secondary instance when I need it and went the s3270/x3270-script way instead.

The resulting script isn't something I'm particularly proud of, especially as it misses error handling that really should be there. But this is not expect instead you operate on whole screens of data and z/VM is not particularly helpful in telling you that you just completed your logon either. Anyway, it seems to work for me. It downloads the most recent stable or daily image if they are not present yet, uploads them via DFT to CMS and makes sure that the installation does not terminate when the script disconnects. Sadly DFT is pretty slow, so I'm stuck with 70 kB/s and about five minutes of waiting until kernel and initrd are finally uploaded. Given that installations themselves are usually blazingly fast on System z, I'm not too annoyed by that, though.

I previously wrote about a parmfile example that sets enough options to bring debian-installer to the point of a working network console via SSH without further prompting. It's a little unfortunate that s390-netdevice needs to be preseeded with the hardware addresses of the network card in all cases, even if only one is available. I should go and fix that. For now this means that the parmfile will be dependent on the actual VM system definition. With that in mind there is an example script in the same gist that writes out a parmfile and then calls the reinstall script mentioned above. Given that debian-installer now supports HTTPS (so far only in the daily images) you can even do a reasonably secure bootstrapping of the network console credentials and preseeding settings.

If you put this pretty generic preseed configuration file onto a securely accessible webserver and reference it from the parmfile, you can also skip the more tedious questions at the beginning of debian-installer. A secure transport is encouraged as preseed files can do anything to your installation process. Unfortunately it seems that there is no way to preseed SSH keys for the resulting installation yet, neither for the created user nor for root. So I haven't achieved my desired target of a fully automated installation just yet. Debian's Jenkins setup just went with insecure defaults, but given that my sponsored VMs are necessarily connected to the public Internet that seemed like a bad idea to me. I suppose one way out would be to IP/password ACL the preseed file. Another one to somehow get SSH key support into user-setup.

8 July 2016

Russell Coker: Nexus 6P and Galaxy S5 Mini

Just over a month ago I ordered a new Nexus 6P [1]. I ve had it for over a month now and it s time to review it and the Samsung Galaxy S5 Mini I also bought. Security The first noteworthy thing about this phone is the fingerprint scanner on the back. The recommended configuration is to use your fingerprint for unlocking the phone which allows a single touch on the scanner to unlock the screen without the need to press any other buttons. To unlock with a pattern or password you need to first press the power button to get the phone s attention. I have been considering registering a fingerprint from my non-dominant hand to reduce the incidence of accidentally unlocking it when carrying it or fiddling with it. The phone won t complete the boot process before being unlocked. This is a good security feature. Android version 6 doesn t assign permissions to apps at install time, they have to be enabled at run time (at least for apps that support Android 6). So you get lots of questions while running apps about what they are permitted to do. Unfortunately there s no allow for the duration of this session option. A new Android feature prevents changing security settings when there is an overlay running . The phone instructs you to disable overlay access for the app in question but that s not necessary. All that is necessary is for the app to stop using the overlay feature. I use the Twilight app [2] to dim the screen and use redder colors at night. When I want to change settings at night I just have to pause that app and there s no need to remove the access from it note that all the web pages and online documentation saying otherwise is wrong. Another new feature is to not require unlocking while at home. This can be a convenience feature but fingerprint unlocking is so easy that it doesn t provide much benefit. The downside of enabling this is that if someone stole your phone they could visit your home to get it unlocked. Also police who didn t have a warrant permitting search of a phone could do so anyway without needing to compel the owner to give up the password. Design This is one of the 2 most attractive phones I ve owned (the other being the sparkly Nexus 4). I think that the general impression of the appearance is positive as there are transparent cases on sale. My phone is white and reminds me of EVE from the movie Wall-E. Cables This phone uses the USB Type-C connector, which isn t news to anyone. What I didn t realise is that full USB-C requires that connector at both ends as it s not permitted to have a data cable with USB-C at the device and and USB-A at the host end. The Nexus 6P ships with a 1M long charging cable that has USB-C at both ends and a ~10cm charging cable with USB-C at one end and type A at the other (for the old batteries and the PCs that don t have USB-C). I bought some 2M long USB-C to USB-A cables for charging my new phone with my old chargers, but I haven t yet got a 1M long cable. Sometimes I need a cable that s longer than 10cm but shorter than 2M. The USB-C cables are all significantly thicker than older USB cables. Part of that would be due to having many more wires but presumably part of it would be due to having thicker power wires for delivering 3A. I haven t measured power draw but it does seem to charge faster than older phones. Overall the process of converting to USB-C is going to be a lot more inconvenient than USB SuperSpeed (which I could basically ignore as non-SuperSpeed connectors worked). It will be good when laptops with USB-C support become common, it should allow thinner laptops with more ports. One problem I initially had with my Samsung Galaxy Note 3 was the Micro-USB SuperSpeed socket on the phone being more fiddly for the Micro-USB charging plug I used. After a while I got used to that but it was still an annoyance. Having a symmetrical plug that can go into the phone either way is a significant convenience. Calendars and Contacts I share most phone contacts with my wife and also have another list that is separate. In the past I had used the Samsung contacts system for the contacts that were specific to my phone and a Google account for contacts that are shared between our phones. Now that I m using a non-Samsung phone I got another Gmail account for the purpose of storing contacts. Fortunately you can get as many Gmail accounts as you want. But it would be nice if Google supported multiple contact lists and multiple calendars on a single account. Samsung Galaxy S5 Mini Shortly after buying the Nexus 6P I decided that I spend enough time in pools and hot tubs that having a waterproof phone would be a good idea. Probably most people wouldn t consider reading email in a hot tub on a cruise ship to be an ideal holiday, but it works for me. The Galaxy S5 Mini seems to be the cheapest new phone that s waterproof. It is small and has a relatively low resolution screen, but it s more than adequate for a device that I ll use for an average of a few hours a week. I don t plan to get a SIM for it, I ll just use Wifi from my main phone. One noteworthy thing is the amount of bloatware on the Samsung. Usually when configuring a new phone I m so excited about fancy new hardware that I don t notice it much. But this time buying the new phone wasn t particularly exciting as I had just bought a phone that s much better. So I had more time to notice all the annoyances of having to download updates to Samsung apps that I ll never use. The Samsung device manager facility has been useful for me in the past and the Samsung contact list was useful for keeping a second address book until I got a Nexus phone. But most of the Samsung apps and 3d party apps aren t useful at all. It s bad enough having to install all the Google core apps. I ve never read mail from my Gmail account on my phone. I use Fetchmail to transfer it to an IMAP folder on my personal mail server and I d rather not have the Gmail app on my Android devices. Having any apps other than the bare minimum seems like a bad idea, more apps in the Android image means larger downloads for an over-the-air update and also more space used in the main partition for updates to apps that you don t use. Not So Exciting In recent times there hasn t been much potential for new features in phones. All phones have enough RAM and screen space for all common apps. While the S5 Mini has a small screen it s not that small, I spent many years with desktop PCs that had a similar resolution. So while the S5 Mini was released a couple of years ago that doesn t matter much for most common use. I wouldn t want it for my main phone but for a secondary phone it s quite good. The Nexus 6P is a very nice phone, but apart from USB-C, the fingerprint reader, and the lack of a stylus there s not much noticeable difference between that and the Samsung Galaxy Note 3 I was using before. I m generally happy with my Nexus 6P, but I think that anyone who chooses to buy a cheaper phone probably isn t going to be missing a lot.

4 October 2015

Philipp Kern: Root on LVM on Debian s390x, new Hercules


Two s390x changes landed in Debian unstable today:
With this it should be possible to install Debian on s390x with root on LVM. I'd be happy to hear feedback about installations with any configuration, be it root on a single DASD or root on LVM. Unless you set both mirror/udeb/suite and mirror/suite to unstable you'll need to wait until the changes are in testing, though. (The debian-installer build does not matter as zipl-installer is not part of the initrd and sysconfig-hardware is part of the installation.)

Furthermore I uploaded a new version of Hercules - a z/Architecture emulator - to get a few more years of maintenance into Debian. See its upstream changelog for details on the changes (old 3.07 new 3.11).

At this point qemu at master is also usable for s390x emulation. It is much faster than Hercules, but it uses newfangled I/O subsystems like virtio. Hence we will need to do some more patching to make debian-installer just work. One patch for netcfg is in to support virtio networking correctly, but then it forces the user to configure a DASD. (Which would be as wrong if Fibre Channel were to be used.) In the end qemu and KVM on s390x look so much like a normal x86 VM that we could drop most of the special-casing of s390x (netcfg-static instead of netcfg; network-console instead of using the VM console; DASD configuration instead of simply using virtio-blk devices; I guess we get to keep zIPL for booting).

19 September 2015

Philipp Kern: Working with z/VM DIRMAINT as a mere user

Two helpful CMS commands to know if the users on the z/VM host you connect to are managed using DIRMAINT:

REVIEW is something I always expire from my mind after a few weeks of not using a mainframe. And then I do not usually find it quickly, even knowing where to look. (For some reason GET won't work unless you are a privileged user of the system.)

I guess by now most of the systems use DIRMAINT, but it's an IBM product that requires a separate license in addition to z/VM. Hence on some systems the user directory is still maintained by hand. In this case the password is written verbatim into the file and the administrator needs to change it manually for you.

30 August 2015

Philipp Kern: Automating the 3270 part of a Debian System z install

If you try to install Debian on System z within z/VM you might be annoyed at the various prompts it shows before it lets you access the network console via SSH. We can do better. From within CMS copy the default EXEC and default PARMFILE:

COPYFILE DEBIAN EXEC A DEBAUTO EXEC A
COPYFILE PARMFILE DEBIAN A PARMFILE DEBAUTO A

Now edit DEBAUTO EXEC A and replace the DEBIAN in 'PUNCH PARMFILE DEBIAN * (NOHEADER' with DEBAUTO. This will load the alternate kernel parameters file into the card reader, while still loading the original kernel and initrd files.

Replace PARMFILE DEBAUTO A's content with this (note the 80 character column limit):

ro locale=C
s390-netdevice/choose_networktype=qeth s390-netdevice/qeth/layer2=true
s390-netdevice/qeth/choose=0.0.fffc-0.0.fffd-0.0.fffe
netcfg/get_ipaddress=<IPADDR> netcfg/get_netmask=255.255.255.0
netcfg/get_gateway=<GW> netcfg/get_nameservers=<FIRST-DNS>
netcfg/confirm_static=true netcfg/get_hostname=debian
netcfg/get_domain=
network-console/authorized_keys_url=http://www.kern.lc/id_rsa.pub
preseed/url=http://www.kern.lc/preseed-s390x.cfg

Replace <IPADDR>, <GW>, and <FIRST-DNS> to suit your local network config. You might also need to change the netmask, which I left in for clarity about the format. Adjust the device address of your OSA network card. If it's in layer 3 mode (very likely) you should set layer2=false. Note that mixed case matters, hence you will want to SET CASE MIXED in xedit.

Then there are the two URLs that need to be changed. The authorized_keys_url file contains your SSH public key and is fetched unencrypted and unauthenticated, so be careful what networks you traverse with your request (HTTPS is not supported by debian-installer in Debian).

preseed/url is needed for installation parameters that do not fit the parameters file - there is an upper character limit that's about two lines longer than my example. This is why this example only contains the bare minimum for the network part, everything else goes into this preseeding file. It file can optionally be protected with a MD5 checksum in preseed/url/checksum.

Both URLs need to be very short. I thought that there was a way to specify a line continuation, but in my tests I was unable to produce one. Hence it needs to fit on one line, including the key. You might want to use an IPv4 as the hostname.

To skip the initial boilerplate prompts and to skip straight to the user and disk setup you can use this as preseed.cfg:

d-i debian-installer/locale string en_US
d-i debian-installer/country string US
d-i debian-installer/language string en
d-i time/zone US/Eastern
d-i mirror/country manual
d-i mirror/http/mirror string httpredir.debian.org
d-i mirror/http/directory string /debian
d-i mirror/http/proxy string

I'm relatively certain that the DASD disk setup part cannot be automated yet. But the other bits of the installation should be preseedable just like on non-mainframe hardware.

18 February 2015

Philipp Kern: Caveats of the HP MicroServer Gen8

If you intend to buy the HP MicroServer Gen8 as a home server there are a few caveats that I didn't find on the interwebs before I bought the device:
  • Even though the main chassis fan is now fixed in AHCI mode with recent BIOS versions, there is still an annoying PSU fan that's tiny and high frequency. You cannot control it and the PSU seems to be custom-built.
  • The BIOS does not support ACPI S3 (suspend-to-RAM) at all. Apparently it being a server BIOS they chose to not include the code paths in the BIOS needed to properly turn off devices and turn them back on. This means that it's not possible to simply suspend it and have it woken up when your media center boots.
  • In contrast to the older AMD-based MicroServers the Gen8 comes with iLO, which will consume quite a few watts just for being present even if you don't use it. I read figures of about ten watts. It also cannot be turned off, as it does system management like fan control.
  • The HDD cages are not vibration proof or decoupled.
If you try to boot FreeBSD with its zfsloader you will likely need to apply a workaround patch, because the BIOS seems to do something odd. Linux works as expected.

13 October 2014

Philipp Kern: pbuilder and pam_tmpdir

It turns out that my recent woes with pbuilder were all due to libpam-tmpdir being installed (at least two old bug reports exist about this issue: #576425 and #725434). I rather like my private temporary directory that cannot be accessed by other (potential) users on the same system. Previously I used a hook to fix this up by ensuring that the directory actually exists in the chroot, but somehow that recently broke.

A rather crude but working solution seems to be "session required pam_env.so user_readenv=1" in /etc/pam.d/sudo and "TMPDIR=/tmp" in /root/.pam_environment. One could probably skip pam_tmpdir.so for root, but I did not want to start fighting with pam-auth-update as this is in /etc/pam.d/common-session*.

14 January 2014

Daniel Pocock: PostFinance gives back my money

14 days with no response to written requests for a refund of the error. After a few hours of objective scrutiny on this blog, however, the money was put back: Thanks to all those who provided comments, especially Philipp Kern who found the paper form that reveals how bad the online standing order form really is, it is quite possible that was a factor in convincing PostFinance to take some responsibility. It is also possible that the contact center staff were not even aware of the way the standing order form is viewed by the customer, they may have been looking at some alternative form that had been generated by regurgitating the user input. These are just some examples of the problems that occur (and require thorough and professional analysis) when business processes go online and nobody has a paper trail to prove what they really meant.

29 November 2013

Philipp Kern: On PDiffs Usefulness for Stable

Axel just said that PDiffs are really useful for stable because it changes seldom. The truth is that there are no PDiffs for stable. I consider this a bug because you need to download a huge blob on every point release even though only few stanzas changed.

The real problem of PDiffs is the count that needs to be applied. We run "dinstall" much more often now than we used to and we cannot currently skip diffs in the middle when looking at a dak-maintained repository. It would be more useful if you could fetch a single diff from some revision to the current state and apply this instead of those (download, apply, hash check)+ cycles. 56 available index diffs are also not particularly helpful in this regard. They cover 14 days with four dinstalls each, but it takes a very long time to apply them, even on modern machines.

I know that there was ongoing work improving PDiffs that wanted to use git to generate the intermediate diffs. The current algorithm used in dak does not require old versions except one to be kept, but keeping everything is the far other end of the spectrum where you have a git repository that potentially gets huge unless you rewrite it. It should be possible to just implement a rolling ring buffer of Packages files to diff against, reprepro already generates the PDiffs in the right way, the Index format is flexible enough to support this. So someone would just need to make that bit of work in dak.

19 November 2013

Rapha&#235;l Hertzog: Will Debian s technical committee coopt Keith Packard or Philipp Kern?

The process has been ongoing for more than a year but the Debian technical committee is about to select a candidate to recommend for its vacant seat. The Debian Project Leader will then (likely) appoint him (looks like it won t be a women). According to recent discussions on debian-ctte@lists.debian.org, it seems that either Keith Packard or Philipp Kern will join the committee. If you look at the current membership of the committee, you will see:
  • Bdale Garbee: USA
  • Russ Allbery: USA
  • Don Armstrong: USA
  • Andreas Barth: Germany
  • Ian Jackson: United Kingdom
  • Steve Langasek: USA
  • Colin Watson: United Kingdom
That s very Anglo-Saxon centric (6 out of 7 members). While I trust the current members and while I know that they are open-minded people, it still bothers me to see this important body with so few diversity. Coming back to the choice at hand, Keith Packard is American and Philipp Kern is German. No new country in the mix. I can only hope that Philipp will be picked to bring some more balance in the body.

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23 September 2013

Russell Coker: Hive Bluetooth Stereo Speakers

picture of Hive bluetooth speakers I ve just been given a set of Hive Bluetooth speakers by MobileZap (see this link for all their Bluetooth speakers) [1]. The speakers charge by a micro-USB cable so I started charging them in my car immediately after collecting them. To connect them to a phone or other Bluetooth device you just press the Bluetooth button on top and get the phone to be visible and scanning for devices, they identify themselves as Hive , after that they just work. My first test of using them was playing Ingress and the quality of the sound was impressive, I had thought that the Ingress recommendation to use headphones was due to the risk of annoying other people or alerting other players, but the quality of the sound was impressive and the internal speakers of a phone can t do it justice. After getting home I did some tests listening to music. For watching music videos it didn t work so well as the sound was too far removed from the video, but the audio quality was very good. I listened to Vow by Garbage (a good benchmark for stereo sound) and even though the Hive speakers are only 16.5cm wide I could still notice the stereo effect when they were about 1.5m away from me. The audio quality didn t compare well with my Bose QC-15 headphones, but for affordable and portable speakers it was quite good and an obvious improvement over the speakers that are built in to any phone I ve used. According to the Bluetooth Wikipedia page the range of a class 2 device is 10m and the range of a class 3 device is 1m. When my Samsung Galaxy Note 2 is talking to it I get a reliable range of about 5 meters and a mostly working range of 6 or 7 meters (sound randomly drops out and gets choppy). It could be that other phones would support a longer range due to having a higher transmission power (either class 1 or being closer to the limits of class 2) and a more sensitive receiver. But it doesn t seem likely that a 5m range is going to be a problem. Volume and Quality The speakers are rated at 5 Watt, when running at maximum volume (both through the phone volume setting and the volume control on the speakers) the sound is reasonably distortion free, as good as can be expected from playing an MP3 that s not compressed with the highest quality. Sound Meter [2] reports the sound volume as almost 85dB on a Galaxy S3 and as almost 100dB on a Galaxy Note 2, that would be somewhere between the volume of a busy street or alarm clock and the volume of a subway train or blow dryer which seems like a reasonable description, I find it very unpleasant to be within a meter of the speakers at maximum volume. With the typical amount of background noise in my house I can play music on the Hive speakers at one end of my house and hear it clearly at the other end. These speakers are more than capable of supplying the music for any party I d want to host or attend. I m not really into wild parties, but I think that anyone who has a one room party would be more than satisfied with the Hive speakers. Obviously the sound quality of portable speakers in a box that s 16.5cm wide and 6cm high isn t going to equal that of a full size set of speakers, but I think that hardly anyone who attends a party would expect better sound quality than the Hive speakers can provide. The aim of such speakers is to be portable, not really expensive, and to provide good sound quality within those constraints. I think that they meet such aims well. Over the years there have been many occasions when I have used a Thinkpad to provide the music for a party and found it to be quite loud enough. My current Thinkpad is a T420 which can produce 75dB according to my Galaxy S3 or 85dB according to my Galaxy Note 2. So it seems that I only really need about 10dB less than the maximum volume of the Hive speakers. Appearance The designers obviously made an effort on the appearance of the device. They have gone with the Hive concept and used hexagons everywhere. It really looks nice. Unfortunately when I took the photo there was some dust on it which didn t look bad to the eye but caught the camera flash. But with a matte black device there s always the problem of light colored dust. Even with a bit of dust it still looks great as a set of speakers, the dust just detracts from the appearance in photos. Line In One of the features I looked for was an audio line input so I could connect it directly to a non-Bluetooth device. I m assuming that this feature works as it s something that s difficult to stuff up when designing such a product, but I haven t got around to testing it. Once I started using the device I just found that I didn t have a real need for that feature. One thing that it might be useful for is PC desktop speakers that are powered by a USB port on the monitor. Currently I have a bearable (but not great) set of speakers for each PC and I don t need to change anything. But having the option of another set of speakers is very handy in case I suddenly need to make hardware changes. Other People s Reviews When I review a product I generally try and get opinions from random other people if possible. My mother and my mother-in-law were both impressed by the Hive speakers and expressed interest in owning a set. My mother-in-law was particularly interested as she uses her phone to listen to radio stations from outside Australia (I m going to get her onto Aldi for cheap 3G data ASAP so she can listen to Internet radio when travelling). Generally the impression that other people have of this device seems to be very positive. It seems that Bluetooth speakers aren t just a Geek toy. Conclusion While I m very impressed by this product, at this stage I m not sure whether I would pay for this one or something cheaper if I was paying for it. MobileZap offers a range of other products that look appealing at lower price points. It really depends on how much I use it. I ve just got a Makerbot Replicator 3D printer working and I ve found the Hive speakers very useful for the purpose of drowning out it s noise. If I keep doing that sort of thing then I ll get enough use out of the speakers to justify the price.

16 September 2013

Philipp Kern: buildd.debian.org

Did you notice that it was gone? It's back now. Phew. Apparently an upgrade to wheezy was scheduled for the passed week-end. This went badly with the RAID controller acting up after the upgrade. So the move to a new machine (or rather VM) was sped up. And because various policies changed, we needed to move to a dedicated database server with a new authentication scheme, get rid of the /org symlink, get rid of the buildd_* accounts, cope with a new PHP, cope with rlimits that broke a Python CGI (thanks, KiBi!), triggers that weren't tickled, and various other stuff. Thanks to DSA for handling the underlying infrastructure despite some communication issues during heavy fire fighting.

26 August 2013

Russell Coker: Scratching a Galaxy S

Some years ago when I first got a LG U990 Viewty (which in some ways is the best phone I ever owned) I went swimming and left my phone in my bag. My phone happened to rest on my car keys and had vibration mode enabled, after a couple of missed calls I had a nasty scratched area on the phone screen. Since then I ve been very wary about allowing metal objects to come in contact with a phone screen. Now I have a Samsung Galaxy S with some sort of motherboard damage (it won t even boot and I know it s not a software issue because it was initially intermittent). A phone that old isn t worth repairing (they sell on ebay for as little as $50) so it seemed worth testing how hard the screen is. The screen cover is Gorilla Glass which was the hardest glass available at the time the phone was new (apparently there are better versions of Gorilla Glass available now and my more recent phones should be tougher). My first test was with one of my favorite Japanese kitchen knives, it didn t scratch at all. Then I chose a knife sharpening stone as an obvious item that s harder than a knife, it scratched the screen easily. A quartz pebble also scratched the screen when I used some force, so presumably concrete and brick would also scratch it. Tests with all current Australian coins and my car keys showed that the screen is too hard to be scratched by them. I also tested hitting the phone screen with my keys, I hit it much harder than would happen if I was to run while having my phone and my keys in the same pocket and there was no damage. My conclusion is that any metal object you are likely to carry in your pocket is unlikely to cause any problem if knocked against the screen of a modern phone.

10 July 2013

Russell Coker: Samsung Galaxy Note 2

A few weeks ago I bought a new Samsung Galaxy Note 2 Android phone. As I predicted in my post about Phone and Tablet Sizes [1] the Note 2 with a 5.55 display is a bit too big for me to have an ideal single handed side grasp (I estimate that about 5.2 would be ideal). But I can stretch a bit and move it around in my hand to touch all parts of the screen with my thumb. Although when doing that I don t have a tight grip, with my previous phone the Samsung Galaxy S3 [2] I could properly wrap my hand around it to grip it tightly while using it with one hand. The Note 2 will be easier for me to drop or for a thief to snatch it from me. While the big screen makes the phone difficult to use with one hand it does allow viewing more data. The ConnectBot SSH client (Play Store link) [3] (F-Droid repository link) [4] works a lot better on a larger screen I ve also discovered that the volume control buttons can be used to change the font size in ConnectBot which is handy as the default is really tiny. Also Klaus Weidner s Hacker s Keyboard (Play Store link) [5] (F-Droid repository link) [6] works a lot better with a larger screen. When I tested the Hacker s keyboard on a smaller phone I found the 5 row layout too difficult to use, but on the Note 2 it works well. As an aside I wish I could quickly and easily toggle between 4 row mode (good for SMS) and 5 row mode (good for sysadmin work) in the Hackers Keyboard. For less serious use the large screen on the Note 2 is good for watching TV. I ve got a collection of mp4s of TV shows that I ve been meaning to watch, now I watch them in bed on my phone. Another advantage of the Note 2 is the battery life. When playing Ingress and doing all the usual email checks etc my Note 2 will last about as long as my wife s Galaxy S3 with it s power case. So without any extra batteries a Note 2 will probably last about twice as long as a Galaxy S3. The Note 2 has more RAM than the S3 I used to use (I had the S3 with 1G of RAM) and it also apparently has a faster CPU. The CPU speed hasn t been an issue for me but the extra RAM is a real benefit, it means that I can usually switch between Ingress and other programs without having to restart Ingress each time. As an aside I think that Google and LG should release a Nexus Ingress 4 phone or some other device that s optimised for Ingress, I m sure it would sell well. Some people make a big deal about the stylus that comes with the Note 2. It is a neat feature to have the device know when the stylus tip is hovering over the screen but it s not very useful for me. If I was going to create art work on a phone (as some people do) then it would interest me, but I m more interested in email and ssh for fine input and my fingers are generally good enough for those tasks. I have got thin fingers, so I think that people with thicker fingers could really benefit from the stylus. I recently bought a batch of stylus pens from Kogan which have a pen at one end and a rubber stylus tip at the other for fat fingered people I know who need to use an Android phone but can t afford a Note or Note 2. I also like the software build on it which is almost the same as that on the Galaxy S3. It seems that many people prefer the apparently stock features on the Nexus 4 but I like the way Samsung does things. Conclusion I m very happy with my new phone. The bigger screen allows me to see things more clearly, this is good for web browsing, reading email, and now that I can use the Hackers Keyboard I can type more effectively. The longer battery life is really good too, although I think that Samsung could have done better if the phone was 3mm thicker then it could have a much bigger battery and have a larger CCD for the camera. I don t think that the phone is really different, at least not for my use. Samsung has promoted it for artistic use and I ve seen evidence to support their claims. But for most people it ll just be a phone with a larger screen and a bigger battery. Some people criticise it for being too big, but it s still smaller than the handsets on most desk phones so it s not big by the standards of old fashioned phones. The increased size has not only allowed me to do the same things more effectively but also allowed me to do things I hadn t tried doing on a phone before such as watching TV. This isn t because of the phone being particularly special in any way, it s just that the change in size gives more possibilities for ways of using it. The Samsung Galaxy Mega is the largest smart phone. The 5.8 version of the Mega has a resolution of only 960*540 (less than the Note and Note 2 not good enough IMHO) and the 6.3 version has the same resolution as the Note 2 of 1280*720. I think that both Mega variants are too big for me, I need to be able to use a phone with one hand. So it seems that the Note 2 is probably the best phone for me right now.

29 May 2013

Russell Coker: Nexus 4

My wife has had a LG Nexus 4 for about 4 months now so it s time for me to review it and compare it to my Samsung Galaxy S3. A Sealed Case The first thing to note about the Nexus 4 is that it doesn t support changing a battery or using micro-SD storage. The advantage of these design choices is that it allows reduced weight and greater strength compared to what the phone might otherwise be. Such choices would also allow the phone to be slightly cheaper which is a massive advantage, it s worth noting that the Nexus 4 is significantly cheaper than any other device I can buy with comparable specs. My wife s phone has 8G of storage (not RAM thanks Robin) and cost $369 at the start of the year while the current price is $349 for the 8G version and $399 for the 16G version. Of course one down-side of this is that if you need 16G of storage then you need to spend an extra $50 on the 16G phone instead of buying a phone with 8G of storage and inserting a 16GB micro-SD card which costs $19 from OfficeWorks. Also there s no option of using a 32G SD card (which costs less than $50) or a 64G SD card. Battery etc The battery on the Nexus 4 isn t nearly big enough, when playing Ingress it lasts about half as long as my Galaxy S3, about 90 minutes to fully discharge. If it was possible to buy a bigger battery from a company like Mugan Power then the lack of battery capacity wouldn t be such a problem. But as it s impossible to buy a bigger battery (unless you are willing to do some soldering) the only option is an external battery. I was unable to find a Nexus 4 case which includes a battery (which is probably because the Nexus 4 is a lot less common than the Galaxy S3) so my wife had to buy an external battery. If you are serious about playing Ingress with a Nexus 4 then you will end up with a battery in your pocket and cable going to your phone from the battery, this is a real annoyance. While being a cheap fast phone with a clear screen makes it well suited to Ingress the issue of having a cable permanently attached is a real down-side. One significant feature of the Nexus 4 is that it supports wireless charging. I have no immediate plans to use that feature and the wireless charger isn t even on sale in Australia. But if the USB connector was to break then I could buy a wireless charger from the US and keep using the phone, while for every other phone I own a broken connector would render the phone entirely useless. Screen Brightness I have problems with my Galaxy S3 not being bright enough at midday when on auto brightness. I have problems with my wife s Nexus 4 being too bright in most situations other than use at midday. Sometimes at night it s painfully bright. The brightness of the display probably contributes to the excessive battery use. I don t know whether all Nexus 4 devices are like this or whether there is some variance. In any case it would be nice if the automatic screen brightness could be tuned so I could make it brighter on my phone and less bright on my wife s. According to AndroSensor my Galaxy S3 thinks that the ambient light in my computer room is 28 lux while my wife s Nexus 4 claims it s 4 lux. So I guess that part of the problem is the accuracy of the light sensors in the phones. On-Screen Buttons I am a big fan of hardware buttons. Hardware buttons work reliably when your fingers are damp and can be used by feel at night. My first Android phone the Sony-Ericsson Xperia X10 had three hardware buttons for settings, home, and back as well as buttons for power, changing volume, and taking a photo which I found very convenient. My Galaxy S3 has hardware buttons for power, home, and volume control. I think that Android phones should have more hardware buttons not less. Unfortunately it seems that Google and the phone manufacturers disagree with me and the trend is towards less buttons. Now the Nexus 4 only has hardware buttons for power, and volume control. One significant advantage of the Galaxy S3 over the Nexus 4 is that the S3 s settings and back buttons while not implemented in hardware are outside the usable screen area. So the 4.8 1280*720 display is all for application data while the buttons for home, settings, and back on the Nexus 4 take up space on the screen so only a subset of the 4.7 1280*768 is usable by applications. While according to specs the Nexus 4 has a screen almost as big as the Galaxy S3 and a slightly higher resolution in practice it has an obviously smaller screen with fewer usable pixels. Also one of the changes related to having the buttons on-screen means that the settings button is often in the top right corner which I find annoying. I didn t like that aspect of the GUI the first time I used a tablet running Android 3.0 and I still don t like it now. GPS My wife s Nexus 4 seems to be much less accurate than my Galaxy S3 for GPS. I don t know how much of this is due to phone design and how much is due to random factors in manufacturing. I presume that a large portion of it is due to random manufacturing issues because other people aren t complaining about it. Maybe she just got unlucky with an inaccurate phone. Shape and Appearance One feature that I really like in the Samsung Galaxy S is that it has a significant ridge surrounding the screen. If you place a Galaxy S face-down on a desk that makes it a lot less likely to get a scratch on the screen. The LG U990 Viewty also had a similar ridge. Of course the gel case I have bought for every Android phone has solved this problem, but it would really be nice to have a phone that I consider usable without needing to buy such a case. The Nexus 4 has a screen that curves at the edges which if anything makes the problem worse than merely lacking a ridge around the edge. On the up-side the Nexus 4 looks and feels nice before you use it. The back of the Nexus 4 sparkles, that s nice but when you buy a gel case (which doesn t seem to be optional with modern design trends) you don t get to see it. The Nexus 4 is a very attractive package, it s really a pity that they didn t design it to be usable without a gel case. Conclusion Kogan is currently selling the Galaxy S3 with 16G of storage for $429. When comparing that to the 16G version of the Nexus 4 at $399 that means there s a price of $30 to get a SD socket, the option of replacing a battery, one more hardware button, and more screen space. So when comparing the Google offers for the Nexus 4 with the Kogan offer on the Galaxy S3 or the Galaxy Note which also has 16G of storage and sells for $429 the Google offer doesn t seem appealing to me. The Nexus 4 is still a good phone and is working well for my wife, but she doesn t need as much storage as I do. Also when she got her phone the Galaxy S3 was much more expensive than it is now. Also Kogan offer the 16G version of the Nexus 4 for $389 which makes it more appealing when compared to the Galaxy S3. It s surprising that they can beat Google on price. Generally I recommend the Nexus 4 without hesitation to anyone who wants a very capable phone for less than $400 and doesn t need a lot of storage. If you need more storage then the Galaxy S3 is more appealing. Also if you need to use a phone a lot then a Galaxy S3 with a power case works well in situations where the Nexus 4 performs poorly.

27 May 2013

Petter Reinholdtsen: How to install Linux on a Packard Bell Easynote LV preinstalled with Windows 8

Two days ago, I asked how I could install Linux on a Packard Bell EasyNote LV computer preinstalled with Windows 8. I found a solution, but am horrified with the obstacles put in the way of Linux users on a laptop with UEFI and Windows 8. I never found out if the cause of my problems were the use of UEFI secure booting or fast boot. I suspect fast boot was the problem, causing the firmware to boot directly from HD without considering any key presses and alternative devices, but do not know UEFI settings enough to tell. There is no way to install Linux on the machine in question without opening the box and disconnecting the hard drive! This is as far as I can tell, the only way to get access to the firmware setup menu without accepting the Windows 8 license agreement. I am told (and found description on how to) that it is possible to configure the firmware setup once booted into Windows 8. But as I believe the terms of that agreement are completely unacceptable, accepting the license was never an alternative. I do not enter agreements I do not intend to follow. I feared I had to return the laptops and ask for a refund, and waste many hours on this, but luckily there was a way to get it to work. But I would not recommend it to anyone planning to run Linux on it, and I have become sceptical to Windows 8 certified laptops. Is this the way Linux will be forced out of the market place, by making it close to impossible for "normal" users to install Linux without accepting the Microsoft Windows license terms? Or at least not without risking to loose the warranty? I've updated the Linux Laptop wiki page for Packard Bell EasyNote LV, to ensure the next person do not have to struggle as much as I did to get Linux into the machine. Thanks to Bob Rosbag, Florian Weimer, Philipp Kern, Ben Hutching, Michael Tokarev and others for feedback and ideas.

3 March 2013

Philipp Kern: git-annex: encrypted remotes

Due to the data loss I blogged about, I had to reverse engineer the encryption used by git-annex for its encrypted special remotes. The file system on which the content lived has a bullet hole of 8 GB in it, which was helpfully discarded by pvmove. It's pretty unhappy about that fact, parts of the git repository are unusable and directories cannot be accessed anymore. git-annex cannot possibly run anymore.

However, I was still able to access the git-annex branch within said git repository (using porcelain). This branch contains a file called remote.log which contains the keys of the special remotes. There's one per remote, encrypted to a GPG key of your choice and all files within that remote are encrypted with the same symmetric key.

One small detail stopped me from getting the decryption right the first time, though. It seems that git-annex uses randomness generated by GPG and armored into base64. In my na vet I spotted the base64 and decoded it. Instead it's used verbatim: the first 256 bytes as HMAC key (which reduces randomness to 192 bytes) and the remaining bytes for the symmetric key used by GPG (which will do another key derivation for CAST5 with it). A bug about that just hit the git-annex wiki.

With that knowledge in mind I wrote a little tool that's able to generate encrypted content keys from the plain ones used in the symlinks. That helps you to locate the file in the encrypted remote. Fetch it and then use the tool to decrypt the file in question with the right key.

The lesson: Really backup the git repository used with git-annex and especially remote.log. I'm now missing most of the metadata but for some more important files it's luckily still present. Recovery of the file content does not depend on it if you can deduce the filename from the content. If you have many little files it might be a bit futile without it, though.

2 March 2013

Philipp Kern: PSA: LVM, pvmove and SSDs

If you use LVM with Wheezy on a solid-state drive, you really want to install the latest lvm2 update (i.e. 2.02.95-6, which contains the changes of -5). Otherwise, if you set issue_discards=1 in /etc/lvm/lvm.conf, you will experience severe data loss when using pvmove. Happened to me twice, once I didn't care (chroot data being lost), the second time (today) I did. Not fun, especially when the backup of the data was scheduled for the same day.

One has to wonder why it takes three months for a bug that trashes data to reach testing. (Obviously I know the answer, but they're not particularly good reasons.) Other distributions, like Ubuntu, were much quicker to notice and incorporate that fix. And in the case of the named distribution not because they auto-synced it from unstable. If somebody notices such a grave bug, please yell at people to get the fix out there to our users. Thanks.

8 February 2013

Philipp Kern: Mozilla's direction

Am I the only one who's disappointed with the route Mozilla's taking and left wondering what the direction is? First they killed off the development of Thunderbird because, as we all know, people mainly use webmail these days. Then they presented us their view that the big Certificate Authorities are too big to fail, as CAs gravely violated our trust (c.f. Trustwave and their MitM authority). And "now" they're also blocking the introduction of new formats into their browser because they cannot be the one who innovates. Instead Microsoft and Apple obviously need to take the lead in introducing a format into their browsers because otherwise it wouldn't be useful. Even though it's safe to say that Chrome and Firefox make up for more than half of the desktop browser market share. It might be that Chrome's nibbling from Firefox's, still IE seems to be in decline and Safari is rather a further mention than something many people would care strongly about.

There were of course some valid reasons for not supporting WebP yet. But most of them got fixed in the meantime and all we hear is the referal to proprietary vendors who need to move first. If I'd want to depend on such vendors I'd go with proprietary operating systems. (Having to deal with hardware products of proprietary vendors at $dayjob is enough.) So what's up Mozilla? The solution is to ignore your users and tag bugs with patches wontfix?

The only real advantage of Firefox over Chromium these days is the vast amount of plugins and extensions (e.g. Pentadactyl, for which there is no real equivalent available). Another sad fact is that you need to pull Firefox from a 3rd party repository (even though packages are coming from the 2nd party) to get a current version onto your Debian system to work with the web. But then it's not Mozilla who's to blame here. Maybe we should've introduced one Iceweasel version that's allowed to have reverse-dependencies and one that cannot.

(This post might contain hyberboles, which should be considered as such.)

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