Back in my last post on this topic, I'd got shell on my doorbell but hadn't figured out why the HTTP callbacks weren't always firing. I still haven't, but I have learned some more things.

Doorbird sell a chime, a network connected device that is signalled by the doorbell when someone pushes a button. It costs about $150, which seems excessive, but would solve my problem (ie, that if someone pushes the doorbell and I'm not paying attention to my phone, I miss it entirely). But given a shell on the doorbell, how hard could it be to figure out how to mimic the behaviour of one?

Configuration for the doorbell is all stored under /mnt/flash, and there's a bunch of files prefixed 1000eyes that contain config (1000eyes is the German company that seems to be behind Doorbird). One of these was called 1000eyes.peripherals, which seemed like a good starting point. The initial contents were "Peripherals":[] , so it seemed likely that it was intended to be JSON. Unfortunately, since I had no access to any of the peripherals, I had no idea what the format was. I threw the main application into Ghidra and found a function that had debug statements referencing "initPeripherals and read a bunch of JSON keys out of the file, so I could simply look at the keys it referenced and write out a file based on that. I did so, and it didn't work - the app stubbornly refused to believe that there were any defined peripherals. The check that was failing was pcVar4 = strstr(local_50[0],PTR_s_"type":"_0007c980);, which made no sense, since I very definitely had a type key in there. And then I read it more closely. strstr() wasn't being asked to look for "type":, it was being asked to look for "type":". I'd left a space between the : and the opening " in the value, which meant it wasn't matching. The rest of the function seems to call an actual JSON parser, so I have no idea why it doesn't just use that for this part as well, but deleting the space and restarting the service meant it now believed I had a peripheral attached.

The mobile app that's used for configuring the doorbell now showed a device in the peripherals tab, but it had a weird corrupted name. Tapping it resulted in an error telling me that the device was unavailable, and on the doorbell itself generated a log message showing it was trying to reach a device with the hostname bha-04f0212c5cca and (unsurprisingly) failing. The hostname was being generated from the MAC address field in the peripherals file and was presumably supposed to be resolved using mDNS, but for now I just threw a static entry in /etc/hosts pointing at my Home Assistant device. That was enough to show that when I opened the app the doorbell was trying to call a CGI script called peripherals.cgi on my fake chime. When that failed, it called out to the cloud API to ask it to ask the chime[1] instead. Since the cloud was completely unaware of my fake device, this didn't work either. I hacked together a simple server using Python's HTTPServer and was able to return data (another block of JSON). This got me to the point where the app would now let me get to the chime config, but would then immediately exit. adb logcat showed a traceback in the app caused by a failed assertion due to a missing key in the JSON, so I ran the app through jadx, found the assertion and from there figured out what keys I needed. Once that was done, the app opened the config page just fine.

Unfortunately, though, I couldn't edit the config. Whenever I hit "save" the app would tell me that the peripheral wasn't responding. This was strange, since the doorbell wasn't even trying to hit my fake chime. It turned out that the app was making a CGI call to the doorbell, and the thread handling that call was segfaulting just after reading the peripheral config file. This suggested that the format of my JSON was probably wrong and that the doorbell was not handling that gracefully, but trying to figure out what the format should actually be didn't seem easy and none of my attempts improved things.

So, new approach. Rather than writing the config myself, why not let the doorbell do it? I should be able to use the genuine pairing process if I could mimic the chime sufficiently well. Hitting the "add" button in the app asked me for the username and password for the chime, so I typed in something random in the expected format (six characters followed by four zeroes) and a sufficiently long password and hit ok. A few seconds later it told me it couldn't find the device, which wasn't unexpected. What was a little more unexpected was that the log on the doorbell was showing it trying to hit another bha-prefixed hostname (and, obviously, failing). The hostname contains the MAC address, but I hadn't told the doorbell the MAC address of the chime, just its username. Some more digging showed that the doorbell was calling out to the cloud API, giving it the 6 character prefix from the username and getting a MAC address back. Doing the same myself revealed that there was a straightforward mapping from the prefix to the mac address - changing the final character from "a" to "b" incremented the MAC by one. It's actually just a base 26 encoding of the MAC, with aaaaaa translating to 00408C000000.

That explained how the hostname was being generated, and in return I was able to work backwards to figure out which username I should use to generate the hostname I was already using. Attempting to add it now resulted in the doorbell making another CGI call to my fake chime in order to query its feature set, and by mocking that up as well I was able to send back a file containing X-Intercom-Type, X-Intercom-TypeId and X-Intercom-Class fields that made the doorbell happy. I now had a valid JSON file, which cleared up a couple of mysteries. The corrupt name was because the name field isn't supposed to be ASCII - it's base64 encoded UTF16-BE. And the reason I hadn't been able to figure out the JSON format correctly was because it looked something like this:

"Peripherals":[] "prefix": "type":"DoorChime","name":"AEQAbwBvAHIAYwBoAGkAbQBlACAAVABlAHMAdA==","mac":"04f0212c5cca","user":"username","password":"password" ]

Note that there's a total of one [ in this file, but two ]s? Awesome. Anyway, I could now modify the config in the app and hit save, and the doorbell would then call out to my fake chime to push config to it. Weirdly, the association between the chime and a specific button on the doorbell is only stored on the chime, not on the doorbell. Further, hitting the doorbell didn't result in any more HTTP traffic to my fake chime. However, it did result in some broadcast UDP traffic being generated. Searching for the port number led me to the Doorbird LAN API and a complete description of the format and encryption mechanism in use. Argon2I is used to turn the first five characters of the chime's password (which is also stored on the doorbell itself) into a 256-bit key, and this is used with ChaCha20 to decrypt the payload. The payload then contains a six character field describing the device sending the event, and then another field describing the event itself. Some more scrappy Python and I could pick up these packets and decrypt them, which showed that they were being sent whenever any event occurred on the doorbell. This explained why there was no storage of the button/chime association on the doorbell itself - the doorbell sends packets for all events, and the chime is responsible for deciding whether to act on them or not.

On closer examination, it turns out that these packets aren't just sent if there's a configured chime. One is sent for each configured user, avoiding the need for a cloud round trip if your phone is on the same network as the doorbell at the time. There was literally no need for me to mimic the chime at all, suitable events were already being sent.

Still. There's a fair amount of WTFery here, ranging from the strstr() based JSON parsing, the invalid JSON, the symmetric encryption that uses device passwords as the key (requiring the doorbell to be aware of the chime's password) and the use of only the first five characters of the password as input to the KDF. It doesn't give me a great deal of confidence in the rest of the device's security, so I'm going to keep playing.

[1] This seems to be to handle the case where the chime isn't on the same network as the doorbell

comments

Like many I use pass for storing usernames and passwords. This gives me easy access to credentials in a secure manner. I don't like the way that the metadata (i.e. filenames) are public, but that aside it is a robust tool I've been using for several years. The last time I talked about pass was when I talked about showing the age of my credentials, via the integrated git support. That then became a pass-plugin:

  frodo ~ $ pass age
  6 years ago GPG/root@localhost.gpg
  6 years ago GPG/steve@steve.org.uk.OLD.gpg
  ..
  4 years, 8 months ago Domains/Domain.fi.gpg
  4 years, 7 months ago Mobile/dna.fi.gpg
  ..
  1 year, 3 months ago Websites/netlify.com.gpg
  1 year ago Financial/ukko.fi.gpg
  1 year ago Mobile/KiK.gpg
  4 days ago Enfuce/sre.tst.gpg
  ..

Anyway today's work involved writing another plugin, named env. I store my data in pass in a consistent form, each entry looks like this:

   username: steve
   password: secrit
   site: http://example.com/login/blah/
   # Extra data

The keys vary, sometimes I use "login", sometimes "username", other times "email", but I always label the fields in some way. Recently I was working with some CLI tooling that wants to have a username/password specified and I patched it to read from the environment instead. Now I can run this:

     $ pass env internal/cli/tool-name
     export username="steve"
     export password="secrit"

That's ideal, because now I can source that from within a shell:

   $ source <(pass env internal/cli/tool-name)
   $ echo username
   steve

Or I could directly execute the tool I want:

   $ pass env --exec=$HOME/ldap/ldap.py internal/cli/tool-name
   you are steve
   ..

TLDR: If you store your password entries in "key: value" form you can process them to export $KEY=$value, and that allows them to be used without copying and pasting into command-line arguments (e.g. "~/ldap/ldap.py --username=steve --password=secrit")

Like many I use pass for storing usernames and passwords. This gives me easy access to credentials in a secure manner. I don't like the way that the metadata (i.e. filenames) are public, but that aside it is a robust tool I've been using for several years. The last time I talked about pass was when I talked about showing the age of my credentials, via the integrated git support. That then became a pass-plugin:

  frodo ~ $ pass age
  6 years ago GPG/root@localhost.gpg
  6 years ago GPG/steve@steve.org.uk.OLD.gpg
  ..
  4 years, 8 months ago Domains/Domain.fi.gpg
  4 years, 7 months ago Mobile/dna.fi.gpg
  ..
  1 year, 3 months ago Websites/netlify.com.gpg
  1 year ago Financial/ukko.fi.gpg
  1 year ago Mobile/KiK.gpg
  4 days ago Enfuce/sre.tst.gpg
  ..

Anyway today's work involved writing another plugin, named env. I store my data in pass in a consistent form, each entry looks like this:

   username: steve
   password: secrit
   site: http://example.com/login/blah/
   # Extra data

The keys vary, sometimes I use "login", sometimes "username", other times "email", but I always label the fields in some way. Recently I was working with some CLI tooling that wants to have a username/password specified and I patched it to read from the environment instead. Now I can run this:

     $ pass env internal/cli/tool-name
     export username="steve"
     export password="secrit"

That's ideal, because now I can source that from within a shell:

   $ source <(pass env internal/cli/tool-name)
   $ echo username
   steve

Or I could directly execute the tool I want:

   $ pass env --exec=$HOME/ldap/ldap.py internal/cli/tool-name
   you are steve
   ..

TLDR: If you store your password entries in "key: value" form you can process them to export $KEY=$value, and that allows them to be used without copying and pasting into command-line arguments (e.g. "~/ldap/ldap.py --username=steve --password=secrit")

I have uploaded most of my Machine Learning lecture to YouTube. The slides are in English, but the audio is in German. Some very basic contents (e.g., a demo of standard k-means clustering) were left out from this advanced class, and instead only a link to recordings from an earlier class were given. In this class, I wanted to focus on the improved (accelerated) algorithms instead. These are not included here (yet). I believe there are some contents covered in this class you will find nowhere else (yet). The first unit is pretty long (I did not split it further yet). The later units are shorter recordings. ML F1: Principles in Machine Learning

• Principles in Machine Learning
• Principles in Machine Learning /2
• Occam s Razor Principle of Parsimony
• Simple Models
• Computational Learning Theory
• Probably Approximately Correct Learning (PAC Learning) /1
• Probably Approximately Correct Learning (PAC Learning) /2
• PAC Learnable Examples
• VC Dimension (Vapnik-Chervonenkis-Dimension )
• VC Dimension Example
• Error Bounds and the VC Dimension
• No Free Lunch
• No Free Lunch Theorem
• No Free Lunch Theorem Explanation
• Bias-Variance Tradeoff
• Bias-Variance Tradeoff
• Bias vs. Variance
• Bias-Variance Decomposition
• Bias-Variance Illustration
• Different Kinds of Bias
• Data Often Has Bias
• AI Can Be Sexist and Racist
• Relationships

ML F2/F3: Correlation does not Imply Causation & Multiple Testing Problem

• Correlation does not Imply Causation
• Correlation does not Imply Causation /2
• Correlation does not Imply Causation /3
• Correlation with Statistics Classes
• Multiple Testing Problem
• Bonferroni s Principle Multiple Testing Problem
• Multiple Testing Problem

ML F4: Overfitting beranpassung

• Overfitting
• Underfitting and Overfitting
• Overfitting Decision Tree
• Overfitting Due to Noise
• Overfitting Due to Insufficient Examples

ML F5: Fluch der Dimensionalit t Curse of Dimensionality

• Curse of Dimensionality
• Combinatorial Explosion
• Concentration of Distances
• Data is in the Margins
• Illustration: Shrinking Hyperspheres
• Illustration: Shrinking Hyperspheres /2
• Effect on Search in High Dimensionality
• Summary

ML F6: Intrinsische Dimensionalit t Intrinsic Dimensionality

• Intrinsic Dimensionality
• Estimating Intrinsic Dimensionality
• Angle-Based Intrinsic Dimensionality Intuition
• Angle-Based Intrinsic Dimensionality (ABID) /2
• Consequences & Solutions

ML F7: Distanzfunktionen und hnlichkeitsfunktionen

• Distance Functions
• Distances, Metrics and Similarities
• Distances, Metrics and Similarities /2
• Distance Functions
• Distance Functions /2
• Similarity Functions
• Distances for Binary Data
• Jaccard Coefficient for Sets
• Example Distances for Categorical Data
• Mahalanobis Distance
• Scaling & Normalization
• To Scale, or not to Scale?
• To Scale, or not to Scale? /2

ML L1: Einf hrung in die Klassifikation

• Classification
• Prediction Problems
• Classification: A Multi-Stage Process
• Classification Problem
• Example
• Process of Constructing a Model
• Process of Applying the Model

ML L2: Evaluation und Wahl von Klassifikatoren

• Evaluation and Selection of Classifiers
• Quick Recap: Classification
• Classifier Evaluation: Confusion Matrix
• Classifier Evaluation: Accuracy and Error-Rate
• Precision, Recall, and F-measure
• Classifier Evaluation: Multi-Class Confusion Matrix
• Training Accuracy vs. Accuarcy on New Data
• The Need for Validation
• Holdout Validation
• Cross-Validation
• Bootstrap Validation
• Considerations for Selecting a Model

ML L3: Bayes-Klassifikatoren

• Bayesian Classification
• Bayes Classification: Motivation
• Bayes Theorem: Review
• Optimal Bayes Classifier
• Na ve Bayes Classifier
• Probability Models for a Single Attribute
• Multivariate Gaussian Bayes Classification
• Na ve Bayes Classifier: Example
• Na ve Bayes Classifier: Computational Aspects
• Na ve Bayes Classifier: Comments & Discussion

ML L4: N chste-Nachbarn Klassifikation

• Nearest-Neighbor Classification
• Nearest Neighbor Classifier Motivation
• Nearest Neighbor Classifier: Foundations
• Nearest Neighbor Classifier: Example
• Nearest Neighbor Classification: Example
• Nearest Neighbor Decision Rules

ML L5: N chste Nachbarn und Kerndichtesch tzung

• Nearest-Neighbor as Density estimation
• Nearest Neighbor Classification and Density Estimation
• Predicting with Kernel Density Estimation with k=1,3,5,15
• Error Probability of Nearest Neighbors
• Nearest Neighbor Regression
• Nearest-Neighbor Classification: Comments & Discussion

ML L6: Lernen von Entscheidungsb umen

• Decision Tree Learning
• Example (Variant of a Dataset in )
• Decision Tree Example
• Decision Trees as Rule-based Systems
• Basic Notions
• Constructing a Decision Tree /1
• Visual Interpretation of Decision Trees on R
• Constructing a Decision Tree /2
• Decision Tree Classification: Example

ML L7: Splitkriterien bei Entscheidungsb umen

• Decision Tree Splitting
• Split for Categorical Attributes
• Split for Numeric Attributes
• Best Split Example
• Quality Measures for Splits
• Measure of Impurity: Gini Index
• Gini-Index: Example
• Information Gain
• Information Gain: Example
• Information Gain: Gain-Ratio
• Gain-Ratio: Beispiel
• Classification Error
• Gini, Entropy and Classification Error
• Comparing Split Selection Measures
• Splits for Numerical Attributes

ML L8: Ensembles und Meta-Learning: Random Forests und Gradient Boosting

• Ensembles and Meta-Learning
• Ensembles and Meta-Learning
• Error-Rate of Ensembles
• Random Forests
• Boosting
• Random Forest Classification: Example
• Gradient Boosting Classification: Example

ML L9: Support Vector Machinen - Motivation

• Support Vector Machine Motivation
• Support Vector Machines
• Support Vector Machines /2
• Finding the Best Separating Hyperplane
• Maximum Margin Hyperplane

ML L10: Affine Hyperebenen und Skalarprodukte Geometrie f r SVMs

• Affine Hyperplanes and Scalar Products
• Affine Hyperplanes
• Scalar Products
• Affine Hyperplanes /2

ML L11: Maximum Margin Hyperplane die breitest m gliche Stra e

• Maximum Margin Hyperplane
• A Na ve Attempt
• Support Vectors Separable Data
• Computing the Maximum Margin Hyperplane (MMH)
• Computing the Maximum Margin Hyperplane (MMH) /2
• Boundary of the Maximum Margin Hyperplane (MMH)
• Deriving the Primal SVM Optimization Problem

ML L12: Training Support Vector Machines

• Training Support Vector Machines
• Optimization Problem
• Karush-Kuhn-Tucker KKT Conditions
• Switching to the Dual Problem
• Classification with the Dual SVM
• Optimizing the i
• Optimizing SVMs
• Sequential Minimal Optimization
• Further Improvements

ML L13: Non-linear SVM and the Kernel Trick

• Non-linear SVM and the Kernel Trick
• Nonlinear SVM
• Nonlinear SVM /2
• Kernel Functions
• Soft Margin SVM Classifier
• Soft Margin SVM Classifier /2
• Soft Margin SVM Classifier /3
• Soft Margin SVM Classifier /4

ML L14: SVM Extensions and Conclusions

• SVM Extensions and Conclusions
• Separation of more than 2 Classes
• Support Vector Regression
• Support Vector Regression Optimization Problem
• Support Vector Regression Dual
• Support Vector Data Description (SVDD)
• SVDD Dual Problem
• Support Vector Clustering
• SVMs: Comments & Discussion

ML L15: Motivation of Neural Networks

• Neural Networks
• Biological Background (Simplified)
• Biological Background (Simplified) /2

ML L16: Threshold Logic Units

• Threshold Logic Units
• Threshold Logic Units (TLUs)
• Threshold Logic Units Example
• Geometric Interpretation of TLUs
• Exclusive-Or (XOR) Problem
• Exclusive-Or (XOR) Problem /2
• Exclusive-Or (XOR) Problem /3
• Universality of TLUs
• Mark I Perceptron

ML L17: General Artificial Neural Networks

• General Artificial Neural Networks
• Simplifying Threshold Logic Units
• Weight Matrices
• From TLUs to Multilayer Perceptrons
• Some Activation Functions
• Some Activation Functions /2
• Some Activation Functions /3
• Some Activation Functions /4

ML L18: Learning Neural Networks with Backpropagation

• Learning Neural Networks with Backpropagation
• Basic Gradient Descent
• Stochastic Gradient Descent
• Learning Single-Layer Perceptrons
• Backpropagation
• Training with Backpropagation

ML L19: Deep Neural Networks

• Deep Neural Networks
• Universal Approximation Theorem
• Deep vs. Wide Neural Networks
• High vs. Low Dimensionality
• (Early) Problems of Deep Learning
• Autoencoders
• Layer-wise Pre-Training of Deep Neural Networks
• Dropout Regularization
• Batch Normalization
• Choosing Activation Functions

ML L20: Convolutional Neural Networks

• Convolutional Neural Networks
• Depth vs. Convolutional Kernel Size
• Increasing the Training Data

ML L21: Recurrent Neural Networks and LSTM

• Recurrent Neural Networks
• Recurrent Neural Networks (RNNs) on Sequences
• Recurrent Neural Networks (RNN)
• Long-Short Term Memory (LSTM)
• Further Developments

ML L22: Conclusion Classification

• Conclusion
• Other Classifiers
• Problems of Classification

ML U1: Einleitung Clusteranalyse

• Cluster Analysis Introduction
• What is Clustering?
• What is Clustering? /2
• Applications of Clustering
• Basic Steps for Clustering

ML U2: Hierarchisches Clustering

• Hierarchical Agglomerative Clustering
• Distance of Clusters
• AGNES Agglomerative Nesting
• AGNES Agglomerative Nesting /2
• Extracting Clusters from a Dendrogram
• Benefits and Limitations of HAC

ML U3: Accelerating HAC mit Anderberg s Algorithmus

• Accelerating Hierarchical Clustering
• Complexity of Hierarchical Clustering
• Anderberg s Caching
• AGNES vs. Anderberg , NNChain , SLINK
• Example: Hierarchical Clustering with Anderberg

ML U4: k-Means Clustering

• K-means Clustering
• The Sum of Squares Objective
• The Standard Algorithm (Lloyd s Algorithm)
• Non-determinism & Non-optimality
• Initialization
• Initialization /2
• Complexity of k-Means Clustering

ML U5: Accelerating k-Means Clustering

• Accelerating k-Means Clustering
• k-Means++: Weighted Random Initialization
• Making k-means Faster
• Bounding the Distances Elkan and Hamerly
• Hamerly s k-means
• Example: k-Means Clustering with Hamerly s Algorithm
• Speedup with Hamerly, Elkan, and Exponion

ML U6: Limitations of k-Means Clustering

• Limitations of k-Means Clustering
• Benefits and Drawbacks of k-Means
• Choosing the Optimum k for k-Means
• Limitations of k-Means

ML U7: Extensions of k-Means Clustering

• Extensions of k-Means Clustering
• k-Means and Distances
• k-Means Minimizes Sum of Squares, not Euclidean Distance!
• k-Means Variations for Other Distances
• Spherical k-Means for Text Clustering
• Pre-processing and Post-processing

ML U8: Partitioning Around Medoids (k-Medoids)

• Partitioning Around Medoids (k-Medoids)
• k-medoids Clustering
• Partitioning Around Medoids
• Algorithm: Partitioning Around Medoids
• Algorithm: Partitioning Around Medoids /2
• Change in TD
• Finding the Best Swap Faster
• k-Medoids, k-Means style
• Example for the Inferiority of k-Means Style k-Medoids

ML U9: Gaussian Mixture Modeling (EM Clustering)

• Gaussian Mixture Modeling Introduction
• Expectation-Maximization in Clustering
• Fitting Multiple Gaussian Distributions
• Gaussian Mixture Modeling as E-M-Optimization
• Algorithm: EM Clustering
• Numerical Issues in GMM

ML U10: Gaussian Mixture Modeling Demo

• Gaussian Mixture Modeling Demo

ML U11: BIRCH and BETULA Clustering

• BIRCH and BETULA
• BIRCH Clustering
• BIRCH Clustering Features
• BIRCH Distances
• BIRCH CF-Tree
• BETULA Cluster Features
• BETULA Distance Computations
• Accelerating k-Means with BIRCH and BETULA
• Accelerating GMM with BETULA

ML U12: Motivation Density-Based Clustering (DBSCAN)

• Motivation Density-Based Clustering
• Density-based Clustering: Core Idea

ML U13: Density-reachable and density-connected (DBSCAN Clustering)

• Density-Based Clustering Fundamentals
• Density-based Clustering: Foundations
• Density-based Clustering: Foundations /2
• Density-based Clustering: Foundations /3
• Density-reachability and Density-connectivity
• Density-reachability

ML U14: DBSCAN Clustering

• DBSCAN
• Clustering Approach
• Abstract DBSCAN Algorithm
• DBSCAN Algorithm
• DBSCAN Algorithm /2
• DBSCAN Algorithm /3
• DBSCAN in Context

ML U15: Parameterization of DBSCAN

• DBSCAN Parameterization
• Choosing DBSCAN parameters
• Choosing DBSCAN parameters /2
• Choosing DBSCAN parameters /3

ML U16: Extensions and Variations of DBSCAN Clustering

• DBSCAN Extensions
• Generalized Density-based Clustering
• Grid-based Accelerated DBSCAN
• Anytime Density-Based Clustering (AnyDBC)
• Hierarchical DBSCAN* (HDBSCAN*)
• Improved DBSCAN Variations

ML U17: OPTICS Clustering

• OPTICS Clustering
• Density-based Hierarchical Clustering
• Density-based Hierarchical Clustering /2
• OPTICS Clustering
• Cluster Order
• OPTICS Algorithm

ML U18: Cluster Extraction from OPTICS Plots

• Cluster Extraction from OPTICS Plots
• OPTICS Reachability Plots
• Extracting Clusters from OPTICS Reachability Plots
• Role of the Parameters and minPts

ML U19: Understanding the OPTICS Cluster Order

• Understanding the OPTICS Cluster Order
• Properties of the OPTICS Cluster Order
• Cluster Order as Serialized Spanning Tree
• OPTICS as Density Spanning Trees
• Cluster Order to Dendrograms

ML U20: Spectral Clustering

• Spectral Clustering
• Minimum Cuts
• Graph Laplacian
• From Clustering Graphs to Clustering Data
• Spectral Clustering
• Spectral Clustering is Related to DBSCAN

ML U21: Biclustering and Subspace Clustering

• Biclustering and Subspace Clustering
• Biclustering & Subspace Clustering
• Bicluster Patterns
• Density-based Subspace Clustering
• Subspace Clustering with Apriori-Style Search
• Correlation Clustering
• 4C: Computing Correlation Connected Clusters
• Hough Transform
• CASH: Robust Clustering in Arbitrarily Oriented Subspaces

ML U22: Further Clustering Approaches

• Further Clustering Approaches
• CURE Clustering
• ROCK Clustering
• CHAMELEON
• Affinity Propagation Clustering
• Other Density-based Clustering Algorithms
• Further Clustering Approaches

I decided to start work on repeating the tests for my 2006 OSDC paper on Benchmarking Mail Relays [1] and discover how the last 15 years of hardware developments have changed things. There have been software changes in that time too, but nothing that compares with going from single core 32bit systems with less than 1G of RAM and 60G IDE disks to multi-core 64bit systems with 128G of RAM and SSDs. As an aside the hardware I used in 2006 wasn t cutting edge and the hardware I m using now isn t either. In both cases it s systems I bought second hand for under $1000. Pedants can think of this as comparing 2004 and 2018 hardware. BIND I decided to make some changes to reflect the increased hardware capacity and use 2560 domains and IP addresses, which gave the following errors as well as a startup time of a minute on a system with two E5-2620 CPUs.

May  2 16:38:37 server named[7372]: listening on IPv4 interface lo, 127.0.0.1#53
May  2 16:38:37 server named[7372]: listening on IPv4 interface eno4, 10.0.2.45#53
May  2 16:38:37 server named[7372]: listening on IPv4 interface eno4, 10.0.40.1#53
May  2 16:38:37 server named[7372]: listening on IPv4 interface eno4, 10.0.40.2#53
May  2 16:38:37 server named[7372]: listening on IPv4 interface eno4, 10.0.40.3#53
[...]
May  2 16:39:33 server named[7372]: listening on IPv4 interface eno4, 10.0.47.0#53
May  2 16:39:33 server named[7372]: listening on IPv4 interface eno4, 10.0.48.0#53
May  2 16:39:33 server named[7372]: listening on IPv4 interface eno4, 10.0.49.0#53
May  2 16:39:33 server named[7372]: listening on IPv6 interface lo, ::1#53
[...]
May  2 16:39:36 server named[7372]: zone localhost/IN: loaded serial 2
May  2 16:39:36 server named[7372]: all zones loaded
May  2 16:39:36 server named[7372]: running
May  2 16:39:36 server named[7372]: socket: file descriptor exceeds limit (123273/21000)
May  2 16:39:36 server named[7372]: managed-keys-zone: Unable to fetch DNSKEY set '.': not enough free resources
May  2 16:39:36 server named[7372]: socket: file descriptor exceeds limit (123273/21000)

The first thing I noticed is that a default configuration of BIND with 2560 local IPs (when just running in the default recursive mode) takes a minute to start and needed to open over 100,000 file handles. BIND also had some errors in that configuration which led to it not accepting shutdown requests. I filed Debian bug report #987927 [2] about this. One way of dealing with the errors in this situation on Debian is to edit /etc/default/named and put in the following line to allow BIND to access to many file handles:

OPTIONS="-u bind -S 150000"

But the best thing to do for BIND when there are many IP addresses that aren t going to be used for DNS service is to put a directive like the following in the BIND configuration to specify the IP address or addresses that are used for the DNS service:

listen-on   10.0.2.45;  ;

I have just added the listen-on and listen-on-v6 directives to one of my servers with about a dozen IP addresses. While 2560 IP addresses is an unusual corner case it s not uncommon to have dozens of addresses on one system. dig When doing tests of Postfix for relaying mail I noticed that mail was being deferred with DNS problems (error was Host or domain name not found. Name service error for name=a838.example.com type=MX: Host not found, try again . I tested the DNS lookups with dig which failed with errors like the following:

dig -t mx a704.example.com
socket.c:1740: internal_send: 10.0.2.45#53: Invalid argument
socket.c:1740: internal_send: 10.0.2.45#53: Invalid argument
socket.c:1740: internal_send: 10.0.2.45#53: Invalid argument
; <
> DiG 9.16.13-Debian <
> -t mx a704.example.com
;; global options: +cmd
;; connection timed out; no servers could be reached

Here is a sample of the strace output from tracing dig:
bind(20,  sa_family=AF_INET, sin_port=htons(0), 
sin_addr=inet_addr("0.0.0.0") , 16) = 0
recvmsg(20,  msg_namelen=128 , 0)       = -1 EAGAIN (Resource temporarily 
unavailable)
write(4, "\24\0\0\0\375\377\377\377", 8) = 8
sendmsg(20,  msg_name= sa_family=AF_INET, sin_port=htons(53), 
sin_addr=inet_addr("10.0.2.45") , msg_
namelen=16, msg_iov=[ iov_base="86\1 
\0\1\0\0\0\0\0\1\4a704\7example\3com\0\0\17\0\1\0\0)\20\0\0\0\0
\0\0\f\0\n\0\10's\367\265\16bx\354", iov_len=57 ], msg_iovlen=1, 
msg_controllen=0, msg_flags=0 , 0) 
= -1 EINVAL (Invalid argument)
write(2, "socket.c:1740: ", 15)         = 15
write(2, "internal_send: 10.0.2.45#53: Invalid argument", 45) = 45
write(2, "\n", 1)                       = 1
futex(0x7f5a80696084, FUTEX_WAIT_PRIVATE, 0, NULL) = 0
futex(0x7f5a80696010, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7f5a8069809c, FUTEX_WAKE_PRIVATE, 1) = 1
futex(0x7f5a80698020, FUTEX_WAKE_PRIVATE, 1) = 1
sendmsg(20,  msg_name= sa_family=AF_INET, sin_port=htons(53), 
sin_addr=inet_addr("10.0.2.45") , msg_namelen=16, msg_iov=[ iov_base="86\1 
\0\1\0\0\0\0\0\1\4a704\7example\3com\0\0\17\0\1\0\0)\20\0\0\0\0\0\0\f\0\n\0\10's\367\265\16bx\354", 
iov_len=57 ], msg_iovlen=1, msg_controllen=0, msg_flags=0 , 0) = -1 EINVAL 
(Invalid argument)
write(2, "socket.c:1740: ", 15)         = 15
write(2, "internal_send: 10.0.2.45#53: Invalid argument", 45) = 45
write(2, "\n", 1)

Ubuntu bug #1702726 claims that an insufficient ARP cache was the cause of dig problems [3]. At the time I encountered the dig problems I was seeing lots of kernel error messages  neighbour: arp_cache: neighbor table overflow  which I solved by putting the following in /etc/sysctl.d/mine.conf:
net.ipv4.neigh.default.gc_thresh3 = 4096
net.ipv4.neigh.default.gc_thresh2 = 2048
net.ipv4.neigh.default.gc_thresh1 = 1024

Making that change (and having rebooted because I didn t need to run the server overnight) didn t entirely solve the problems. I have seen some DNS errors from Postfix since then but they are less common than before. When they happened I didn t have that error from dig. At this stage I m not certain that the ARP change fixed the dig problem although it seems likely (it s always difficult to be certain that you have solved a race condition instead of made it less common or just accidentally changed something else to conceal it). But it is clearly a good thing to have a large enough ARP cache so the above change is probably the right thing for most people (with the possibility of changing the numbers according to the required scale). Also people having that dig error should probably check their kernel message log, if the ARP cache isn t the cause then some other kernel networking issue might be related.
Preliminary Results
With Postfix I m seeing around 24,000 messages relayed per minute with more than 60% CPU time idle. I m not sure exactly how to count idle time when there are 12 CPU cores and 24 hyper-threads as having only 1 process scheduled for each pair of hyperthreads on a core is very different to having half the CPU cores unused. I ran my script to disable hyper-threads by telling the Linux kernel to disable each processor core that has the same core ID as another, it was buggy and disabled the second CPU altogether (better than finding this out on a production server). Going from 24 hyper-threads of 2 CPUs to 6 non-HT cores of a single CPU didn t change the thoughput and the idle time went to about 30%, so I have possibly halved the CPU capacity for these tasks by disabling all hyper-threads and one entire CPU which is surprising given that I theoretically reduced the CPU power by 75%. I think my focus now has to be on hyper-threading optimisation.
Since 2006 the performance has gone from ~20 messages per minute on relatively commodity hardware to 24,000 messages per minute on server equipment that is uncommon for home use but which is also within range of home desktop PCs. I think that a typical desktop PC with a similar speed CPU, 32G of RAM and SSD storage would give the same performance. Moore s Law (that transistor count doubles approximately every 2 years) is often misquoted as having performance double every 2 years. In this case more than 1024* the performance over 15 years means the performance doubling every 18 months. Probably most of that is due to SATA SSDs massively outperforming IDE hard drives but it s still impressive.
Notes
I ve been using example.com for test purposes for a long time, but RFC2606 specifies .test, .example, and .invalid as reserved top level domains for such things. On the next iteration I ll change my scripts to use .test.
My current test setup has a KVM virtual machine running my bhm program to receive mail which is taking between 20% and 50% of a CPU core in my tests so far. While that is happening the kvm process is reported as taking between 60% and 200% of a CPU core, so kvm takes as much as 4* the CPU of the guest due to the virtual networking overhead   even though I m using the virtio-net-pci driver (the most efficient form of KVM networking for emulating a regular ethernet card). I ve also seen this in production with a virtual machine running a ToR relay node.
I ve fixed a bug where Postal would try to send the SMTP quit command after encountering a TCP error which would cause an infinite loop and SEGV.

[1] https://doc.coker.com.au/papers/benchmarking-mail-relays-and-forwarders/
[2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=987927
[3] https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/1702726


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Review: The Voyage of the Dawn Treader, by C.S. Lewis

Illustrator:	Pauline Baynes
Series:	Chronicles of Narnia #3
Publisher:	Collier Books
Copyright:	1952
Printing:	1978
ISBN:	0-02-044260-2
Format:	Mass market
Pages:	216

There was a boy named Eustace Clarence Scrubb and he almost deserved it.

The Voyage of the Dawn Treader is the third Narnia book in original publication order (see my review of The Lion, the Witch and the Wardrobe for more about reading order). You could arguably start reading here; there are a lot of references to the previous books, but mostly as background material, and I don't think any of it is vital. If you wanted to sample a single Narnia book to see if you'd get along with the series, this is the one I'd recommend. Since I was a kid, The Voyage of the Dawn Treader has held the spot of my favorite of the series. I'm happy to report that it still holds up. Apart from one bit that didn't age well (more on that below), this is the book where the story and the world-building come together, in part because Lewis picks a plot shape that works with what he wants to write about. The younger two Pevensie children, Edmund and Lucy, are spending the summer with Uncle Harold and Aunt Alberta because their parents are in America. That means spending the summer with their cousin Eustace. C.S. Lewis had strong opinions about child-raising that crop up here and there in his books, and Harold and Alberta are his example of everything he dislikes: caricatured progressive, "scientific" parents who don't believe in fiction or mess or vices. Eustace therefore starts the book as a terror, a whiny bully who has only read boring practical books and is constantly scoffing at the Pevensies and making fun of their stories of Narnia. He is therefore entirely unprepared when the painting of a ship in the guest bedroom turns into a portal to the Narnia and dumps the three children into the middle of the ocean. Thankfully, they're in the middle of the ocean near the ship in the painting. That ship is the Dawn Treader, and onboard is Caspian from the previous book, now king of Narnia. He has (improbably) sorted things out in his kingdom and is now on a sea voyage to find seven honorable Telmarine lords who left Narnia while his uncle was usurping the throne. They're already days away from land, headed towards the Lone Islands and, beyond that, into uncharted seas. MAJOR SPOILERS BELOW. Obviously, Eustace gets a redemption arc, which is roughly the first half of this book. It's not a bad arc, but I am always happy when it's over. Lewis tries so hard to make Eustace insufferable that it becomes tedious. As an indoor kid who would not consider being dumped on a primitive sailing ship to be a grand adventure, I wanted to have more sympathy for him than the book would allow. The other problem with Eustace's initial character is that Lewis wants it to stem from "modern" parenting and not reading the right sort of books, but I don't buy it. I've known kids whose parents didn't believe in fiction, and they didn't act anything like this (and kids pick up a lot more via osmosis regardless of parenting than Lewis seems to realize). What Eustace acts like instead is an entitled, arrogant rich kid who is used to the world revolving around him, and it's fascinating to me how Lewis ignores class to focus on educational philosophy. The best part of Eustace's story is Reepicheep, which is just setup for Reepicheep becoming the best part of The Voyage of the Dawn Treader. Reepicheep, the leader of Narnia's talking mice, first appears in Prince Caspian, but there he's mostly played for laughs: the absurdly brave and dashing mouse who rushes into every fight he sees. In this book, he comes into his own as the courage and occasionally the moral conscience of the party. Caspian wants to explore and to find the lords of his past, the Pevensie kids want to have a sea adventure, and Eustace is in this book to have a redemption arc, but Reepicheep is the driving force at the heart of the voyage. He's going to Aslan's country beyond the sea, armed with a nursemaid's song about his destiny and a determination to be his best and most honorable self every step of the way, and nothing is going to stop him. Eustace, of course, takes an immediate dislike to a talking rodent. Reepicheep, in return, is the least interested of anyone on the ship in tolerating Eustace's obnoxious behavior and would be quite happy to duel him. But when Eustace is turned into a dragon, Reepicheep is the one who spends hours with him, telling him stories and ensuring he's not alone. It's beautifully handled, and my only complaint is that Lewis doesn't do enough with the Eustace and Reepicheep friendship (or indeed with Eustace at all) for the rest of the book. After Eustace's restoration and a few other relatively short incidents comes the second long section of the book and the part that didn't age well: the island of the Dufflepuds. It's a shame because the setup is wonderful: a cultivated island in the middle of nowhere with no one in sight, mysterious pounding sounds and voices, the fun of trying to figure out just what these invisible creatures could possibly be, and of course Lucy's foray into the second floor of a house, braving the lair of a magician to find and read one of the best books of magic in fantasy. Everything about how Lewis sets this scene is so well done. The kids are coming from an encounter with a sea serpent and a horrifically dangerous magic island and land on this scene of eerily normal domesticity. The most dangerous excursion is Lucy going upstairs in a brightly lit house with soft carpet in the middle of the day. And yet it's incredibly tense because Lewis knows exactly how to put you in Lucy's head, right down to having to stand with her back to an open door to read the book. And that book! The pages only turn forward, the spells are beautifully illustrated, and the sense of temptation is palpable. Lucy reading the eavesdropping spell is one of the more memorable bits in this series, at least for me, and makes a surprisingly subtle moral point about the practical reasons why invading other people's privacy is unwise and can just make you miserable. And then, when Lucy reads the visibility spell that was her goal, there's this exchange, which is pure C.S. Lewis:

"Oh Aslan," said she, "it was kind of you to come." "I have been here all the time," said he, "but you have just made me visible." "Aslan!" said Lucy almost a little reproachfully. "Don't make fun of me. As if anything I could do would make you visible!" "It did," said Aslan. "Did you think I wouldn't obey my own rules?"

I love the subtlety of what's happening here: the way that Lucy is much more powerful than she thinks she is, but only because Aslan decided to make the rules that way and chooses to follow his own rules, making himself vulnerable in a fascinating way. The best part is that Lewis never belabors points like this; the characters immediately move on to talk about other things, and no one feels obligated to explain. But, unfortunately, along with the explanation of the thumping and the magician, we learn that the Dufflepuds are (remarkably dim-witted) dwarfs, the magician is their guardian (put there by Aslan, no less!), he transformed them into rather absurd shapes that they hate, and all of this is played for laughs. Once you notice that these are sentient creatures being treated essentially like pets (and physically transformed against their will), the level of paternalistic colonialism going on here is very off-putting. It's even worse that the Dufflepuds are memorably funny (washing dishes before dinner to save time afterwards!) and are arguably too dim to manage on their own, because Lewis made the authorial choice to write them that way. The "white man's burden" feeling is very strong. And Lewis could have made other choices! Coriakin the magician is a fascinating and somewhat morally ambiguous character. We learn later in the book that he's a star and his presence on the island is a punishment of sorts, leading to one of my other favorite bits of theology in this book:

"My son," said Ramandu, "it is not for you, a son of Adam, to know what faults a star can commit."

Lewis could have kept most of the setup, kept the delightfully silly things the Dufflepuds believe, changed who was responsible for their transformation, and given Coriakin a less authoritarian role, and the story would have been so much stronger for it. After this, the story gets stranger and wilder, and it's in the last part that I think the true magic of this book lies. The entirety of The Voyage of the Dawn Treader is a progression from a relatively mundane sea voyage to something more awe-inspiring. The last few chapters are a tour de force of wonder: rejuvenating stars, sunbirds, the Witch's stone knife, undersea kingdoms, a sea of lilies, a wall of water, the cliffs of Aslan's country, and the literal end of the world. Lewis does it without much conflict, with sparse description in a very few pages, and with beautifully memorable touches like the quality of the light and the hush that falls over the ship. This is the part of Narnia that I point to and wonder why I don't see more emulation (although I should note that it is arguably an immram). Tolkien-style fantasy, with dwarfs and elves and magic rings and great battles, is everywhere, but I can't think of many examples of this sense of awe and discovery without great battles and detailed explanations. Or of characters like Reepicheep, who gets one of the best lines of the series:

"My own plans are made. While I can, I sail east in the Dawn Treader. When she fails me, I paddle east in my coracle. When she sinks, I shall swim east with my four paws. And when I can swim no longer, if I have not reached Aslan's country, or shot over the edge of the world in some vast cataract, I shall sink with my nose to the sunrise and Peepiceek shall be the head of the talking mice in Narnia."

The last section of The Voyage of the Dawn Treader is one of my favorite endings of any book precisely because it's so different than the typical ending of a novel. The final return to England is always a bit disappointing in this series, but it's very short and is preceded by so much wonder that I don't mind. Aslan does appear to the kids as a lamb at the very end of the world, making Lewis's intended Christian context a bit more obvious, but even that isn't belabored, just left there for those who recognize the symbolism to notice. I was curious during this re-read to understand why The Voyage of the Dawn Treader is so much better than the first two books in the series. I think it's primarily due to two things: pacing, and a story structure that's better aligned with what Lewis wants to write about. For pacing, both The Lion, the Witch and the Wardrobe and Prince Caspian have surprisingly long setups for short books. In The Voyage of the Dawn Treader, by contrast, it takes only 35 pages to get the kids in Narnia, introduce all the characters, tour the ship, learn why Caspian is off on a sea voyage, establish where this book fits in the Narnian timeline, and have the kids be captured by slavers. None of the Narnia books are exactly slow, but Dawn Treader is the first book of the series that feels like it knows exactly where it's going and isn't wasting time getting there. The other structural success of this book is that it's a semi-episodic adventure, which means Lewis can stop trying to write about battles and political changes whose details he's clearly not interested in and instead focus wholeheartedly on sense-of-wonder exploration. The island-hopping structure lets Lewis play with ideas and drop them before they wear out their welcome. And the lack of major historical events also means that Aslan doesn't have to come in to resolve everything and instead can play the role of guardian angel. I think The Voyage of the Dawn Treader has the most compelling portrayal of Aslan in the series. He doesn't make decisions for the kids or tell them directly what to do the way he did in the previous two books. Instead, he shows up whenever they're about to make a dreadful mistake and does just enough to get them to make a better decision. Some readers may find this takes too much of the tension out of the book, but I have always appreciated it. It lets nervous child readers enjoy the adventures while knowing that Aslan will keep anything too bad from happening. He plays the role of a protective but non-interfering parent in a genre that usually doesn't have parents because they would intervene to prevent adventures. I enjoyed this book just as much as I remembered enjoying it during my childhood re-reads. Still the best book of the series. This, as with both The Lion, the Witch and the Wardrobe and Prince Caspian, was originally intended to be the last book of the series. That, of course, turned out to not be the case, and The Voyage of the Dawn Treader is followed (in both chronological and original publication order) by The Silver Chair. Rating: 9 out of 10

The Tor Project now has a status page which shows the state of our major services. You can check status.torprojet.org for news about major outages in Tor services, including v3 and v2 onion services, directory authorities, our website (torproject.org), and the check.torproject.org tool. The status page also displays outages related to Tor internal services, like our GitLab instance. This post documents why we launched status.torproject.org, how the service was built, and how it works.

Why a status page The first step in setting up a service page was to realize we needed one in the first place. I surveyed internal users at the end of 2020 to see what could be improved, and one of the suggestions that came up was to "document downtimes of one hour or longer" and generally improve communications around monitoring. The latter is still on the sysadmin roadmap, but a status page seemed like a good solution for the former. We already have two monitoring tools in the sysadmin team: Icinga (a fork of Nagios) and Prometheus, with Grafana dashboards. But those are hard to understand for users. Worse, they also tend to generate false positives, and don't clearly show users which issues are critical. In the end, a manually curated dashboard provides important usability benefits over an automated system, and all major organisations have one.

Picking the right tool It wasn't my first foray in status page design. In another life, I had setup a status page using a tool called Cachet. That was already a great improvement over the previous solutions, which were to use first a wiki and then a blog to post updates. But Cachet is a complex Laravel app, which also requires a web browser to update. It generally requires more maintenance than what we'd like, needing silly things like a SQL database and PHP web server. So when I found cstate, I was pretty excited. It's basically a theme for the Hugo static site generator, which means that it's a set of HTML, CSS, and a sprinkle of Javascript. And being based on Hugo means that the site is generated from a set of Markdown files and the result is just plain HTML that can be hosted on any web server on the planet.

Deployment At first, I wanted to deploy the site through GitLab CI, but at that time we didn't have GitLab pages set up. Even though we do have GitLab pages set up now, it's not (yet) integrated with our mirroring infrastructure. So, for now, the source is hosted and built in our legacy git and Jenkins services. It is nice to have the content hosted in a git repository: sysadmins can just edit Markdown in the git repository and push to deploy changes, no web browser required. And it's trivial to setup a local environment to preview changes:

hugo serve --baseUrl=http://localhost/
firefox https://localhost:1313/

Only the sysadmin team and gitolite administrators have access to the repository, at this stage, but that could be improved if necessary. Merge requests can also be issued on the GitLab repository and then pushed by authorized personnel later on, naturally.

Availability One of the concerns I have is that the site is hosted inside our normal mirror infrastructure. Naturally, if an outage occurs there, the site goes down. But I figured it's a bridge we'll cross when we get there. Because it's so easy to build the site from scratch, it's actually trivial to host a copy of the site on any GitLab server, thanks to the .gitlab-ci.yml file shipped (but not currently used) in the repository. If push comes to shove, we can just publish the site elsewhere and point DNS there. And, of course, if DNS fails us, then we're in trouble, but that's the situation anyway: we can always register a new domain name for the status page when we need to. It doesn't seem like a priority at the moment. Comments and feedback are welcome!

---

This article was first published on the Tor Project Blog.

I wrote previously about my DeskPi Pro + 8GB Pi 4 setup. My main complaint at the time was the fact one of the forward facing USB ports broke off early on in my testing. For day to day use that hasn t been a problem, but it did mar the whole experience. Last week I received an unexpected email telling me The new updated PCB Board for your DeskPi order was shipped. . Apparently this was due to problems with identifying SSDs and WiFi/HDMI issues. I wasn t quite sure how much of the internals they d be replacing, so I was pleasantly surprised when it turned out to be most of them; including the PCB with the broken USB port on my device. They also provided a set of feet allowing for vertical mounting of the device, which was a nice touch. The USB/SATA bridge chip in use has changed; the original was: and the new one is: That s a move from a JMicron 6Gb/s bridge to an ASMedia 3Gb/s bridge. It seems there are compatibility issues with the JMicron that mean the downgrade is the preferred choice. I haven t retried the original SSD I wanted to use (that wasn t detected), but I did wonder if this might have resolved that issue too. Replacing the PCB was easier than the original install; everything was provided pre-assembled and I just had to unscrew the Pi4 and slot it out, then screw it into the new PCB assembly. Everything booted fine without the need for any configuration tweaks. Nice and dull. I ve tried plugging things into the new USB ports and they seem ok so far as well. However I also then ended up pulling in a new backports kernel from Debian (upgrading from 5.9 to 5.10) which resulted in a failure to boot. The kernel and initramfs were loaded fine, but no login prompt ever appeared. Some digging led to the discovery that a change in boot ordering meant USB was not being enabled. The solution is to add reset_raspberrypi to the /etc/initramfs-tools/modules file - that way this module is available in the initramfs, the appropriate pre-USB reset can happen and everything works just fine again. The other niggle with the new kernel was a regular set of errors in the kernel log: and a set of registers afterwards, roughly every 10s or so. This seems to be fallout from an increase in the core clock due to the VC4 driver now being enabled, the fact I have no SD card in the device and a lack of working card-detect line for the MicroSD slot. There s a GitHub issue but I solved it by removing the sdhci_iproc for now - I m not using the wifi so loss of MMC isn t a problem. Credit to DeskPi for how they handled this. I didn t have to do anything and didn t even realise anything was happening until I got the email with my tracking number and a description of what they were sending out in it. Delivery took less than a week. This is a great example of how to handle a product issue - no effort required on the part of the customer.

Review: Beyond Shame, by Kit Rocha

Series:	Beyond #1
Publisher:	Kit Rocha
Copyright:	December 2013
ASIN:	B00GIA4GN8
Format:	Kindle
Pages:	270

I read this book as part of the Beyond Series Bundle (Books 1-3), which is what the sidebar information is for. Noelle is a child of Eden, the rich and technologically powerful city of a post-apocalyptic world. As the daughter of a councilman, she had everything she wanted except the opportunity to feel. Eden's religious elite embrace a doctrine of strict Puritanism: Even hugging one's children was frowned upon, let alone anything related to sex. Noelle was too rebellious to settle for that, which is why this book opens with her banished from Eden, ejected into Sector Four. The sectors are the city slums, full of gangs and degenerates and violence, only a slight step up from the horrific farming communes. Luckily for her, she literally stumbles into one of the lieutenants of the O'Kane gang, who are just as violent as their reputations but who have surprising sympathy for a helpless city girl. My shorthand distinction between romance and erotica is that romance mixes some sex into the plot and erotica mixes some plot into the sex. Beyond Shame is erotica, specifically BDSM erotica. The forbidden sensations that Noelle got kicked out of Eden for pursuing run strongly towards humiliation, which is tangled up in the shame she was taught to feel about anything sexual. There is a bit of a plot surrounding the O'Kanes who take her in, their leader, some political skulduggery that eventually involves people she knows, and some inter-sector gang warfare, but it's quite forgettable (and indeed I've already forgotten most of it). The point of the story is Noelle navigating a relationship with Jasper (among others) that involves a lot of very graphic sex. I was of two minds about reviewing this. Erotica is tricky to review, since to an extent it's not trying to do what most books are doing. The point is less to tell a coherent story (although that can be a bonus) than it is to turn the reader on, and what turns the reader on is absurdly personal and unpredictable. Erotica is arguably more usefully marked with story codes (which in this case would be something like MF, MMFF, FF, Mdom, Fdom, bd, ds, rom, cons, exhib, humil, tattoos) so that the reader has an idea whether the scenarios in the story are the sort of thing they find hot. This is particularly true of BDSM erotica, since the point is arousal from situations that wouldn't work or might be downright horrifying in a different sort of book. Often the forbidden or taboo nature of the scene is why it's erotic. For example, in another genre I would complain about the exaggerated and quite sexist gender roles, where all the men are hulking cage fighters who want to control the women, but in male-dominant BDSM erotica that's literally the point. As you can tell, I wrote a review anyway, primarily because of how I came to read this book. Kit Rocha (which is a pseudonym for the writing team of Donna Herren and Bree Bridges) recently published Deal with the Devil, a book about mercenary librarians in a post-apocalyptic future. Like every right-thinking person, I immediately wanted to read a book about mercenary librarians, but discovered that it was set in an existing universe. I hate not starting at the beginning of things, so even though there was probably no need to read the earlier books first, I figured out Beyond Shame was the first in this universe and the bundle of the first three books was only $2. If any of you are immediately hooked by mercenary librarians but are back-story completionists, now you know what you'll be getting into. That said, there are a few notable things about this book other than it has a lot of sex. The pivot of the romantic relationship was more interesting and subtle than most erotica. Noelle desperately wants a man to do all sorts of forbidden things to her, but she starts the book unable to explain or analyze why she wants what she wants, and both Jasper and the story are uncomfortable with that and unwilling to leave it alone. Noelle builds up a more coherent theory of herself over the course of the book, and while it's one that's obviously designed to enable lots of erotic scenes, it's not a bad bit of character development. Even better is Lex, the partner (sort of) of the leader of the O'Kane gang and by far the best character in the book. She takes Noelle under her wing from the start, and while that relationship is sexualized like nearly everything in this book, it also turns into an interesting female friendship that I would have also enjoyed in a different genre. I liked Lex a lot, and the fact she's the protagonist of the next book might keep me reading. Beyond Shame also has a lot more female gaze descriptions of the men than is often the case in male-dominant BDSM. The eye candy is fairly evenly distributed, although the gender roles are very much not. It even passes the Bechdel test, although it is still erotica and nearly all the conversations end up being about sex partners or sex eventually. I was less fond of the fact that the men are all dangerous and violent and the O'Kane leader frequently acts like a controlling, abusive psychopath. A lot of that was probably the BDSM setup, but it was not my thing. Be warned that this is the sort of book in which one of the (arguably) good guys tortures someone to death (albeit off camera). Recommendations are next to impossible for erotica, so I won't try to give one. If you want to read the mercenary librarian novel and are dubious about this one, it sounds like (although I can't confirm) that it's a bit more on the romance end of things and involves a lot fewer group orgies. Having read this book, I suspect it was entirely unnecessary to have done so for back-story. If you are looking for male-dominant BDSM, Beyond Shame is competently written, has a more thoughtful story than most, and has a female friendship that I fully enjoyed, which may raise it above the pack. Rating: 6 out of 10

In my previous post I wrote about how I'd been running CP/M on a Z80-based single-board computer. I've been slowly working my way through a bunch of text-based adventure games:

• The Hitchhiker's Guide To The Galaxy
• Zork 1
• Zork 2
• Zork 3

Along the way I remembered how much fun I used to have doing this in my early teens, and decided to write my own text-based adventure. Since I'm not a masochist I figured I'd write something with only three or four locations, and solicited facebook for ideas. Shortly afterwards a "plot" was created and I started work. I figured that the very last thing I wanted to be doing was to be parsing text-input with Z80 assembly language, so I hacked up a simple adventure game in C. I figured if I could get the design right that would ease the eventual port to assembly. I had the realization pretty early that using a table-driven approach would be the best way - using structures to contain the name, description, and function-pointers appropriate to each object for example. In my C implementation I have things that look like this:

 name: "generator",
 desc: "A small generator.",
 use: use_generator,
 use_carried: use_generator_carried,
 get_fn: get_generator,
 drop_fn: drop_generator ,

A bit noisy, but simple enough. If an object cannot be picked up, or dropped, the corresponding entries are blank:

 name: "desk",
 desc: "",
 edesc: "The desk looks solid, but old." ,

Here we see something that is special, there's no description so the item isn't displayed when you enter a room, or LOOK. Instead the edesc (extended description) is available when you type EXAMINE DESK. Anyway over a couple of days I hacked up the C-game, then I started work porting it to Z80 assembly. The implementation changed, the easter-eggs were different, but on the whole the two things are the same. Certainly 99% of the text was recycled across the two implementations. Anyway in the unlikely event you've got a craving for a text-based adventure game I present to you:

• The Lighthouse Of Doom
  • https://github.com/skx/lighthouse-of-doom/

I ve finally found the time to improve the GUI of my pet project: cme (aka Config::Model). Several years ago, I stumbled on a usability problem on the GUI. Some configuration (like OpenSsh or Systemd) feature a lot of configuration parameters. Which means that the GUI displays all these parameters, so finding a specfic parameter might be challenging:

To workaround this problem, I ve added a Filter widget in 2018 which did more or less the job, but it suffered from several bugs which made its behavior confusing. This is now fixed. The Filter widget is now working in a more consistent way. In the example below, I ve typed IdentityFile (1) in the Filter widget to show the identityFile used for various hosts (2):

Which is quite good, but some hosts use the default identity file so no value show up in the GUI. You can then click on hide empty value checkbox to show only the hosts that use a specific identity file:

I hope that this new behavior of the Filter box will make this project more useful. The improved GUI was released with Config::Model::TkUI 1.374. This new version is available on CPAN and on Debian/experimental). It will be released on Debian/unstable once the next Debian version is out. All the best

Review: Learning React, by Alex Banks & Eve Porcello

Publisher:	O'Reilly
Copyright:	June 2020
ISBN:	1-4920-5172-1
Format:	Trade paperback
Pages:	287

My first JavaScript project was a React frontend to a REST service. As part of that project, I read two books: JavaScript: The Definitive Guide to learn the language foundation and this book to learn the framework on top of it. This was an unintentional experiment in the ways programming books can approach the topic. I commented in my review of JavaScript: the Definitive Guide that it takes the reference manual approach to the language. Learning React is the exact opposite. It's goal-driven, example-heavy, and has a problem and solution structure. The authors present a sample application, describe some desired new feature or deficiency in it, and then introduce the specific React technique that solves that problem. There is some rewriting of previous examples using more sophisticated techniques, but most chapters introduce new toy applications along with new parts of the React framework. The best part of this book is its narrative momentum, so I think the authors were successful at their primary goal. The first eight chapters of the book (more on the rest of the book in a moment) feel like a whirlwind tour where one concept flows naturally into the next and one's questions while reading about one technique are often answered in the next section. I thought the authors tried too hard in places and overdid the enthusiasm, but it's very readable in a way that I think may appeal to people who normally find programming books dry. Learning React is also firm and definitive about the correct way to use React, which may appeal to readers who only want to learn the preferred way of using the framework. (For example, React class components are mentioned briefly, mostly to tell the reader not to use them, and the rest of the book only uses functional components.) I had two major problems with this book, however. The first is that this breezy, narrative style turns out to be awful when one tries to use it as a reference. I read through most of this book with both enjoyment and curiosity, sat down to write a React component, and immediately struggled to locate the information I needed. Everything felt logically connected when I was focusing on the problems the authors introduced, but as soon as I started from my own problem, the structure of the book fell apart. I had to page through chapters to locate some nugget buried in the text, or re-read sections of the book to piece together which motivating problem my code was most similar to. It was a frustrating experience. This may be a matter of learning style, since this is why I prefer programming books with a reference structure. But be warned that I can't recommend this book as a reference while you're programming, nor does it prepare you to use the official React documentation as a reference. The second problem is less explicable and less defensible. I don't know what happened with O'Reilly's copy-editing for this book, but the code snippets are a train wreck. The Amazon reviews are full of people complaining about typos, syntax errors, omitted code, and glaring logical flaws, and they are entirely correct. It's so bad that I was left wondering if a very early, untested draft of the examples was somehow substituted into the book at the last minute by mistake. I'm not the sort of person who normally types code in from a book, so I don't care about a few typos or obvious misprints as long as the general shape is correct. The general shape was not correct. In a few places, the code is so completely wrong and incomplete that even combined with the surrounding text I was unable to figure out what it was supposed to be. It's possible this is fixed in a later printing (I read the June 2020 printing of the second edition), but otherwise beware. The authors do include a link to a GitHub repository of the code samples, which are significantly different than what's printed in the book, but that repository is incomplete; many of the later chapter examples are only links to JavaScript web sandboxes, which bodes poorly for the longevity of the example code. And then there's chapter nine of this book, which I found entirely baffling. This is a direct quote from the start of the chapter:

This is the least important chapter in this book. At least, that's what we've been told by the React team. They didn't specifically say, "this is the least important chapter, don't write it." They've only issued a series of tweets warning educators and evangelists that much of their work in this area will very soon be outdated. All of this will change.

This chapter is on suspense and error boundaries, with a brief mention of Fiber. I have no idea what I'm supposed to do with this material as a reader who is new to React (and thus presumably the target audience). Should I use this feature? When? Why is this material in the book at all when it's so laden with weird stream-of-consciousness disclaimers? It's a thoroughly odd editorial choice. The testing chapter was similarly disappointing in that it didn't answer any of my concrete questions about testing. My instinct with testing UIs is to break out Selenium and do integration testing with its backend, but the authors are huge fans of unit testing of React applications. Great, I thought, this should be interesting; unit testing seems like a poor fit for UI code because of how artificial the test construction is, but maybe I'm missing some subtlety. Convince me! And then the authors... didn't even attempt to convince me. They just asserted unit testing is great and explained how to write trivial unit tests that serve no useful purpose in a real application. End of chapter. Sigh. I'm not sure what to say about this book. I feel like it has so many serious problems that I should warn everyone away from it, and yet the narrative introduction to React was truly fun to read and got me excited about writing React code. Even though the book largely fell apart as a reference, I still managed to write a working application using it as my primary reference, so it's not all bad. If you like the problem and solution style and want a highly conversational and informal tone (that errs on the side of weird breeziness), this may still be the book for you. Just be aware that the code examples are a trash fire, so if you learn from examples, you're going to have to chase them down via the GitHub repository and hope that they still exist (or get a later edition of the book where this problem has hopefully been corrected). Rating: 6 out of 10

As you may know, Puppet uses facter to get facts about the machine it is about to configure. That s fine, and a nice concept. One can later use variables in a puppet manifest to do different things depending on what facter tells. For example, the operating system name oh no! This thing is really stupid Here s the code one has to do to be compatible with puppet from version 3 up to 5: if $::lsbdistcodename == undef
# This works around differences between facter versions
if $facts['os']['lsb'] != undef
$distro_codename = $facts['os']['lsb']['distcodename']
else
$distro_codename = $facts['os']['distro']['codename']

else
$distro_codename = downcase($::lsbdistcodename)
Indeed, the global variable $::lsbdistcodename still existed up to Stretch (and is gone in Buster). The global $::facts wasn t an array before (but a hash), so in Jessie, it breaks with the error message facts is not a hash or array when accessing it with os . So, one need the full code above to make this work. It s ok to improve things. It is NOT OK to break os detection. To me it is a very bad practice from upstream Puppet authors. I m publishing this in the hope to avoid others to fall in the same trap as I did.

A new release of drat arrived on CRAN today. This is the first release in a few months (with the last release in July of last year) and it (finally) makes the leap to supporting docs/ in the main branch as we are all so tired of the gh-pages branch. We also have new vignettes, new (and very shiny) documentation and refreshed vignettes! drat stands for drat R Archive Template, and helps with easy-to-create and easy-to-use repositories for R packages. Since its inception in early 2015 it has found reasonably widespread adoption among R users because repositories with marked releases is the better way to distribute code. See below for a few custom reference examples. Because for once it really is as your mother told you: Friends don t let friends install random git commit snapshots. Or as we may now add: stay away from semi-random universes snapshots too. Properly rolled-up releases it is. Just how CRAN shows us: a model that has demonstrated for two-plus decades how to do this. And you can too: drat is easy to use, documented by (now) six vignettes and just works. The NEWS file summarises the release as follows:

Changes in drat version 0.2.0 (2021-04-21)

• A documentation website for the package was added at https://eddelbuettel.github.io/drat/ (Dirk)
• The continuous integration was switched to using r-ci (Dirk)
• The docs/ directory of the main repository branch can now be used instead of gh-pages branch (Dirk in #112)
• A new repository https://github.com/drat-base/drat can now be used to fork an initial drat repository (Dirk)
• A new vignette Drat Step-by-Step was added (Roman Hornung and Dirk in #117 fixing #115 and #113)
• The test suite was refactored for docs/ use (Felix Ernst in #118)
• The minimum R version is now R (>= 3.6) (Dirk fixing #119)
• The vignettes were switched to minidown (Dirk fixing #116)
• A new test file was added to ensure NEWS.Rd is always at the current release version.

Courtesy of my CRANberries, there is a comparison to the previous release. More detailed information is on the drat page. If you like this or other open-source work I do, you can now sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

I m playing with a HP Proliant ML350P Gen8 server (part num 646676-011). For HP servers ML means tower (see the ProLiant Wikipedia page for more details [1]). For HP servers the generation indicates how old the server is, Gen8 was announced in 2012 and Gen10 seems to be the current generation. Debian Packages from HP

wget -O /usr/local/hpePublicKey2048_key1.pub https://downloads.linux.hpe.com/SDR/hpePublicKey2048_key1.pub
echo "# HP RAID" >> /etc/apt/sources.list
echo "deb [signed-by=/usr/local/hpePublicKey2048_key1.pub] http://downloads.linux.hpe.com/SDR/downloads/MCP/Debian/ buster/current non-free" >> /etc/apt/sources.list

The above commands will setup the APT repository for Debian/Buster. See the HP Downloads FAQ [2] for more information about their repositories. hponcfg This package contains the hponcfg program that configures ILO (the HP remote management system) from Linux. One noteworthy command is hponcfg -r to reset the ILO, something you should do before selling an old system. ssacli This package contains the ssacli program to configure storage arrays, here are some examples of how to use it:

# list controllers and show slot numbers
ssacli controller all show
# list arrays on controller identified by slot and give array IDs
ssacli controller slot=0 array all show
# show details of one array
ssacli controller slot=0 array A show
# show all disks on one controller
ssacli controller slot=0 physicaldrive all show
# show config of a controller, this gives RAID level etc
ssacli controller slot=0 show config
# delete array B (you can immediately pull the disks from it)
ssacli controller slot=0 array B delete
# create an array type RAID0 with specified drives, do this with one drive per array for BTRFS/ZFS
ssacli controller slot=0 create type=arrayr0 drives=1I:1:1

When a disk is used in JBOD mode just under 33MB will be used at the end of the disk for the RAID metadata. If you have existing disks with a DOS partition table you can put it in a HP array as a JBOD and it will work with all data intact (GPT partition table is more complicated). When all disks are removed from the server the cooling fans run at high speed, this would be annoying if you wanted to have a diskless workstation or server using only external storage. ssaducli This package contains the ssaducli diagnostic utility for storage arrays. The SSD wear gauge report doesn t work for the 2 SSDs I tested it on, maybe it only supports SAS SSDs not SATA SSDs. It doesn t seem to do anything that I need. storcli This package contains both 32bit and 64bit versions of the MegaRAID utility and deletes whichever one doesn t match the installation in the package postinst, so it fails debsums checks etc. The MegaRAID utility is for a different type of RAID controller to the Smart Storage Array (AKA SSA) that the other utilities work with. As an aside it seems that there are multiple types of MegaRAID controller, the management program from the storcli package doesn t work on a Dell server with MegaRAID. They should have made separate 32bit and 64bit versions of this package. Recommendations Here is HP page for downloading firmware updates (including security updates) [3], you have to login first and have a warranty. This is legal but poor service. Dell servers have comparable prices (on the second hand marker) and comparable features but give free firmware updates to everyone. Dell have overall lower quality of Debian packages for supporting utilities, but a wider range of support so generally Dell support seems better in every way. Dell and HP hardware seems of equal quality so overall I think it s best to buy Dell. Suggestions for HP Finding which of the signing keys to use is unreasonably difficult. You should get some HP employees to sign the HP keys used for repositories with their personal keys and then go to LUG meetings and get their personal keys well connected to the web of trust. Then upload the HP keys to the public key repositories. You should also use the same keys for signing all versions of the repositories. Having different keys for the different versions of Debian wastes people s time. Please provide firmware for all users, even if they buy systems second hand. It is in your best interests to have systems used long-term and have them run securely. It is not in your best interests to have older HP servers perform badly. Having all the fans run at maximum speed when power is turned on is a standard server feature. Some servers can throttle the fan when the BIOS is running, it would be nice if HP servers did that. Having ridiculously loud fans until just before GRUB starts is annoying.

• [1] https://en.wikipedia.org/wiki/ProLiant
• [2] http://downloads.linux.hpe.com/SDR/faq.html
• [3] http://downloads.linux.hpe.com/SDR/project/fwpp/

I had a twitter fight few days back with a gentleman and the article is a result of that fight. Sadly, I do not know the name of the gentleman as he goes via a psuedo name and then again I ve not taken permission from him to quote him in either way. So I will just state the observations I was able to make from the conversations we had. As people who read this blog regularly would know, I am and have been against Railway Privatization which is happening in India. And will be sharing some of the case studies from other countries as to how it panned out for them.

UK Railways

How Privatization Fails : Railways

The Above video is by a gentleman called Shaun who basically shared that privatization as far as UK is concerned is nothing but monopolies and while there are complex reasons for the same, the design of the Railways is such that it will always be a monopoly structure. At the most what you can do is have several monopolies but that is all that can happen. The idea of competition just cannot happen. Even the idea that subsidies will be less or/and trains will run on time is far from fact. Both of these facts have been checked and found to be truthful by fullfact.org. It is and argued that UK is small and perhaps it doesn t have the right conditions. It is probably true but still we do deserve to have a glance at the UK railway map.

UK railway map with operators

The above map is copyrighted to Map Marketing where you could see it today . As can be seen above most companies had their own specified areas. Now if you had looked at the facts then you would have seen that UK fares have been higher. In fact, an oldish article from Metro (a UK publication) shares the same. In fact, UK nationalized its railways effectively as many large rail operators were running in red. Even Scotland is set to nationalised back in March 2022. Remember this is a country which hasn t seen inflation go upwards of 5% in nearly a decade. The only outlier was 2011 where they indeed breached the 5% mark. So from this, what we see is Private Gains and Private Gains Public Losses perhaps seem fit. But then maybe we didn t use the right example. Perhaps Japan would be better. They have bullet trains while UK is still thinking about it. (HS2).

Japanese Railway Below is the map of Japanese Railway

Railway map of Japan with private ownership courtesy Wikimedia commons

Japan started privatizing its railway in 1987 and to date it has not been fully privatized. And on top of it, amount as much as 24 trillion of the long-term JNR debt was shouldered by the government at the expense of taxpayers of Japan while also reducing almost 1/4th of it employees. To add to it, while some parts of Japanese Railways did make profits, many of them made profits by doing large-scale non-railway business mostly real estate of land adjacent to railway stations. In many cases, it seems this went all the way up to 60% of the revenue. The most profitable has been the Shinkansen though. And while it has been profitable, it has not been without safety scandals over the years, the biggest in recent years was the 2005 Amagasaki derailment. What was interesting to me was the Aftermath, while the Wikipedia page doesn t share much, I had read at the time and probably could be found how a lot of ordinary people stood up to the companies in a country where it is a known fact that most companies are owned by the Yakuza. And this is a country where people are loyal to their corporation or company no matter what. It is a strange culture to west and also here in India where people change jobs on drop of hat, although nowadays we have record unemployment. So perhaps Japan too does not meet our standard as it doesn t do competition with each other but each is a set monopoly in those regions. Also how much subsidy is there or not is not really transparent.

U.S. Railways Last, but not the least I share the U.S. Railway map. This is provided by A Mr. Tom Alison on reddit on channel maporn. As the thread itself is archived and I do not know the gentleman concerned, nor have taken permission for the map, hence sharing the compressed version

U.S. Railway lines with the different owners

Now the U.S. Railways is and has always been peculiar as unlike the above two the U.S. has always been more of a freight network. Probably, much of it has to do that in the 1960 s when oil was cheap, the U.S. made zillions of roadways and romanticized the road trip and has been doing it ever since. Also the creation of low-cost airlines definitely didn t help the railways to have more passenger services, in fact the opposite. There are and have been smaller services and attempts of privatization in both New Zealand and Australia and both have been failures. Please see papers in that regard. My simple point is this, as can be seen above, there have been various attempts at privatization of railways and most of them have been a mixed bag. The only one which comes close to what we think as good is Japanese but that also used a lot of public debt which we don t know what will happen on next. Also for higher-speed train services like a bullet train or whatever, you need to direct, no hair pen bends. In fact, a good talk on the topic is the TBD podcast which while it talks about hyperloop, the same questions is and would be asked if were to do in India. Another thing to be kept in mind is that the Japanese have been exceptional builders and this is because they have been forced to. They live in a seismically active zone which made Fukushima disaster a reality but at the same time, their buildings are earthquake-resistant. Standard Disclaimer The above is a simplified version of things. I could have added in financial accounts but that again has no set pattern. For e.g. some Railways use accrual, some use cash and some use hybrid. I could have also shared in either the guage or electrification but all have slightly different standards, although uniguage is something that all Railways aspire for and electrification is again something that all Railways want although in many cases it just isn t economically feasible.

Indian Railways Indian Railways itself recently made the move from Cash to Accrual couple of years back. In-between for a couple of years, it was hybrid. The sad part is and was you can now never measure against past performance in the old way because it is so different. Hence, whether the Railways will be making a loss or a profit, we would come to know only much later. Also, most accountants don t know the new system well, so it is gonna take more time, how much unknown. Sadly, what GOI did a few years back is merge the Railway budget into the Union Budget. Of course, the excuse they gave is too many pressures of new trains, while the truth is, by doing this, they decreased transparency about the whole thing. For e.g. for the last few years, the only state which had significant work being done is in U.P. (Uttar Pradesh) and a bit in Goa, although that is has been protested time and again. I being from the neighborly state of Maharashtra , and have been there several times. Now it does feels all like a dream, going to Goa :(.

Covid news Now before I jump on the news, I should share the movie Virus (2019) which was made by the talented Aashiq Abu. Even though, am not a Malayalee, I still have enjoyed many of his movies simply because he is a terrific director and Malayalam movies, at least most of them have English subtitles and lot of original content.. Interestingly, unlike the first couple of times when I saw it a couple of years back. The first time I saw it, I couldn t sleep a wink for a week. Even the next time, it was heavy. I had shared the movie with mum, and even she couldn t see it in one go. It is and was that powerful Now maybe because we are headlong in the pandemic, and the madness is all around us. There are two terms that helped me though understand a great deal of what is happening in the movie, the first term was altered sensorium which has been defined here. The other is saturation or to be more precise oxygen saturation . This term has also entered the Indian twitter lexicon quite a bit as India has started running out of oxygen. Just today Delhi High Court did an emergency hearing on the subject late at night. Although there is much to share about the mismanagement of the center, the best piece on the subject has been by Miss Priya Ramani. Yup, the same lady who has won against M.J. Akbar and this is when Mr. Akbar had 100 lawyers for this specific case. It would be interesting to see what happens ahead. There are however few things even she forgot in her piece, For e.g. reverse migration i.e. from urban to rural migration started again. Two articles from different entities sharing a similar outlook.Sadly, the right have no empathy or feeling for either the poor or the sick. Even the labor minister Santosh Gangwar s statement that around 1.04 crores were the only people who walked back home. While there is not much data, however some work/research has been done on migration to cites that the number could be easily 10 times as much. And this was in the lockdown of last year. This year, again the same issue has re-surfaced and migrants learning lessons started leaving cities. And I m ashamed to say I think they are doing the right thing. Most State Governments have not learned lessons nor have they done any work to earn the trust of migrants. This is true of almost all state Governments. Last year, just before the lockdown was announced, me and my friend spent almost 30k getting a cab all the way from Chennai to Pune, how much we paid for the cab, how much we bribed the various people just so we could cross the state borders to return home to our anxious families. Thankfully, unlike the migrants, we were better off although we did make a loss. I probably wouldn t be alive if I were in their situation as many didn t. That number is still in the air undocumented deaths Vaccine issues Currently, though the issue has been the Vaccine and the pricing of the same. A good article to get a summation of the issues outlined has been shared on Economist. Another article that goes to the heart of the issue is at scroll. To buttress the argument, the SII chairman had shared this few weeks back

Adar Poonawala talking to Vishnu Som on Left, right center, 7th April 2021.

So, a licensee manufacturer wants to make super-profits during the pandemic. And now, as shared above they can very easily do it. Even the quotes given to nearby countries is smaller than the quotes given to Indian states

Prices of AstraZeneca among various states and countries.

The situation around beds, vaccines, oxygen, anything is so dire that people could go to any lengths to save their loved ones. Even if they know if a certain medicine doesn t work. For e.g. Remdesivir, 5 WHO trials have concluded that it doesn t increase mortality. Heck, even AIIMS chief said the same. But both doctors and relatives desperation to cling on hope has made Remdesivir as a black market drug with unoffical prices hovering anywhere between INR 14k/- to INR30k/- per vial. One of the executives of a top firm was also arrested in Gujarat. In Maharashtra, the opposition M.P. came to the rescue of the officials of Bruick pharms in Mumbai. Sadly, this strange affliction to the party in the center is also there in my extended family. At one end, they will heap praise on Mr. Modi, at the same time they can t get wait to get fast out of India. Many of them have settled in horrors of horror Dubai, as it is the best place to do business, get international schools for the young ones at decent prices, cheaper or maybe a tad more than what they paid in Delhi or elsewhere. Being an Agarwal or a Gupta makes it easier to compartmentalize both things. Ease of doing business, 5 days flat to get a business registered, up and running. And the paranoia is still there. They won t talk on the phone about him because they are afraid they may say something which comes back to bite them. As far as their decision to migrate, can t really blame them. If I were 20-25 yeas younger and my mum were in a better shape than she is, we probably would have migrated as well, although would have preferred Europe than anywhere else.

Internet Freedom and Aarogya Setu App.

Internet Freedom had shared the chilling effects of the Aarogya Setu App. This had also been shared by FSCI in the past, and recently had their handle being banned on Twitter. This was also apparent in a legal bail order which the high court judge gave. While I won t go into the merits and demerits of the bail order, it is astounding for the judge to say that the accused, even though he would be on bail install an app. so he can be surveilled. And this is a high court judge, such a sad state of affairs. We seem to be putting up new lows every day when it comes to judicial jurisprudence. One interesting aspect of the whole case was shared by Aishwarya Iyer. She shared a story that she and her team worked on quint which raises questions on the quality of the work done by Delhi Police. This is of course, up to Delhi Police to ascertain the truth of the matter because unless and until they are able to tie in the PMO s office in for a leak or POTUS s office it hardly seems possible. For e.g. the dates when two heads of state can meet each other would be decided by the secretaries of the two. Once the date is known, it would be shared with the press while at the same time some sort of security apparatus would kick in place. It is incumbent, especially on the host to take as much care as he can of the guest. We all remember that World War 1 (the war to end all wars) started due to the murder of Archduke Ferdinand.

As nobody wants that, the best way is to make sure that a political murder doesn t happen on your watch. Now while I won t comment on what it would be, it would be safe to assume that it would be z+ security along with higher readiness. Especially if it as somebody as important as POTUS. Now, it would be quite a reach for Delhi Police to connect the two dates. They either will have to get creative with the dates or some other way. Otherwise, with practically no knowledge in the public domain, they can t work in limbo. In either case, I do hope the case comes up for hearing soon and we see what the Delhi Police says and contends in the High Court about the same. At the very least, it would be irritating for them to talk of the dates unless they can contend some mass conspiracy which involves the PMO (and would bring into question the constant vetting done by the Intelligence dept. of all those who work in PMO). And this whole case is to kind of shelter to the Delhi riots which happened in which majorly the Muslims died but their deaths lay unaccounted till date

Conclusion In Conclusion, I would like to share a bit of humor because right now the atmosphere is humorless, both with authoritarian tendencies of the Central Govt. and the mass mismanagement of public health which they now have left to the state to do as they fit. The peice I am sharing is from arre, one of my goto sites whenever I feel low.

A new version 0.3.11 of Rblpapi is now arriving at CRAN. It comes two years after the release of version Rblpapit 0.3.10 and brings a few updates and extensions. Rblpapi provides a direct interface between R and the Bloomberg Terminal via the C++ API provided by Bloomberg (but note that a valid Bloomberg license and installation is required). This is the eleventh release since the package first appeared on CRAN in 2016. Changes are detailed below. Special thanks to James, Maxime and Michael for sending us pull requests.

Changes in Rblpapi version 0.3.11 (2021-04-20)

• Support blpAutoAuthenticate and B-PIPE access, refactor and generalise authentication (James Bell in #285)
• Deprecate excludeterm (John in #306)
• Correct example in README.md (Maxime Legrand in #314)
• Correct bds man page (and code) (Michael Kerber, and John, in #320)
• Add GitHub Actions continuous integration (Dirk in #323)
• Remove bashisms detected by R CMD check (Dirk #324)
• Switch vignette to minidown (Dirk in #331)
• Switch unit tests framework to tinytest (Dirk in #332)

Courtesy of my CRANberries, there is also a diffstat report for the this release. As always, more detailed information is on the Rblpapi page. Questions, comments etc should go to the issue tickets system at the GitHub repo. If you like this or other open-source work I do, you can now sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

I ve mostly had the preference of controlling my data rather than depend on someone else. That s one reason why I still believe email to be my most reliable medium for data storage, one that is not plagued/locked by a single entity. If I had the resources, I d prefer all digital data to be broken down to its simplest form for storage, like email format, and empower the user with it i.e. their data. Yes, there are free services that are indirectly forced upon common users, and many of us get attracted to it. Many of us do not think that the information, which is shared for the free service in return, is of much importance. Which may be fair, depending on the individual, given that they get certain services without paying any direct dime.

New age communication So first, we had email and usenet. As I mentioned above, email was designed with fine intentions. Intentions that make it stand even today, independently. But not everything, back then, was that great either. For example, instant messaging was very closed and centralised then too. Things like: ICQ, MSN, Yahoo Messenger; all were centralized. I wonder if people still have access to their ICQ logs. Not much has chagned in the current day either. We now have domination by: Facebook Messenger, Google Whatever the new marketing term they introdcue, WhatsApp, Telegram, Signal etc. To my knowledge, they are all centralized. Over all this time, I m yet to see a product come up with good (business) intentions, to really empower the end user. In this information age, the most invaluable data is user activity. That s one data everyone is after. If you decline to share that bit of free data in exchange for the free services, mind you, that that free service like Facebook, Google, Instagram, WhatsApp, Truecaller, Twitter; none of it would come to you at all. Try it out. So the reality is that while you may not be valuating the data you offer in exchange correctly, there s a lot that is reaped from it. But still, I think each user has (and should have) the freedom to opt in for these tech giants and give them their personal bit, for free services in return. That is a decent barter deal. And it is a choice that one if free to choose

Retaining my data I m fond of keeping an archive folder in my mailbox. A folder that holds significant events in the form of an email usually, if documented. Over the years, I chose to resort to the email format because I felt it was more reliable in the longer term than any other formats. The next best would be plain text. In my lifetime, I have learnt a lot from the internet; so it is natural that my preference has been with it. Mailing Lists, IRCs, HOWTOs, Guides, Blog posts; all have helped. And over the years, I ve come across hundreds of such content that I d always like to preserve. Now there are multiple ways to preserving data. Like, for example, big tech giants. In most usual cases, your data for your lifetime, should be fine with a tech giant. In some odd scenarios, you may be unlucky if you relied on a service provider that went bankrupt. But seriously, I think users should be fine if they host their data with Microsoft, Google etc; as long as they abide by their policies. There s also the catch of alignment. As the user, you should ensure to align (and transition) with the product offerings of your service provider. Otherwise, what may look constant and always reliable, will vanish in the blink of an eye. I guess Google Plus would be a good example. There was some Google Feed service too. Maybe Google Photos in the near decade future, just like Google Picasa in the previous (or current) decade.

History what is On the topic of retaining information, lets take a small drift. I still admire our ancestors. I don t know what went in their mind when they were documenting events in the form of scriptures, carvings, temples, churches, mosques etc; but one things for sure, they were able to leave a fine means of communication. They are all gone but a large number of those events are evident through the creations that they left. Some of those events have been strong enough that further rulers/invaders have had tough times trying to wipe it out from history. Remember, history is usually not the truth, but the statement to be believed by the teller. And the teller is usually the survivor, or the winner you may call. But still, the information retention techniques were better. I haven t visited, but admire whosoever built the Kailasa Temple, Ellora, without which, we d be made to believe what not by all invaders and rulers of the region. But the majestic standing of the temple, is a fine example of the history and the events that have occured in the past.

Ellora Temple - The majectic carving believed to be carved out of a single stone

Dominance has the power to rewrite history and unfortunately that s true and it has done its part. It is just that in a mere human s defined lifetime, it is not possible to witness the transtion from current to history, and say that I was there then and I m here now, and this is not the reality. And if not dominance, there s always the other bit, hearsay. With it, you can always put anything up for dispute. Because there s no way one can go back in time and produce a fine evidence. There s also a part about religion. Religion can be highly sentimental. And religion can be a solid way to get an agenda going. For example, in India - a country which today consitutionally is a secular country, there have been multiple attempts to discard the belief, that never ever did the thing called Ramayana exist. That the Rama Setu, nicely reworded as Adam s Bridge by who so ever, is a mere result of science. Now Rama, or Hanumana, or Ravana, or Valmiki, aren t going to come over and prove that that is true or false. So such subjects serve as a solid base to get an agenda going. And probably we ve even succeeded in proving and believing that there was never an event like Ramayana or the Mahabharata. Nor was there ever any empire other than the Moghul or the British Empire. But yes, whosoever made the Ellora Temple or the many many more of such creations, did a fine job of making a dent for the future, to know of what the history possibly could also be.

Enough of the drift So, in my opinion, having events documented is important. It d be nice to have skills documented too so that it can be passed over generations but that s a debatable topic. But events, I believe should be documented. And documented in the best possible ways so that its existence is not diminished. A documentation in the form of certain carvings on a rock is far more better than links and posts shared on Facebook, Twitter, Reddit etc. For one, these are all corporate entities with vested interests and can pretext excuse in the name of compliance and conformance. So, for the helpless state and generation I am in, I felt email was the best possible independent form of data retention in today s age. If I really had the resources, I d not rely on digital age. This age has no guarantee of retaining and recording information in any reliable manner. Instead, it is just mostly junk, which is manipulative and changeable, conditionally.

Email and RSS So for my communication, I like to prefer emails over any other means. That doesn t mean I don t use the current trends. I do. But this blog is mostly about penning my desires. And desire be to have communication over email format. Such is the case that for information useful over the internet, I crave to have it formatted in email for archival. RSS feeds is my most common mode of keeping track of information I care about. Not all that I care for is available in RSS feeds but hey such is life. And adaptability is okay. But my preference is still RSS. So I use RSS feeds through a fine software called feed2imap. A software that fits my bill fairly well. feed2imap is:

• An rss feed news aggregator
• Pulls and extracts news feeds in the form of an email
• Can push the converted email over pop/imap
• Can convert all image content to email mime attachment

In a gist, it makes the online content available to me offline in the most admired email format In my mail box, in today s day, my preferred email client is Evolution. It does a good job of dealing with such emails (rss feed items). An image example of accessing the rrs feed item through it is below

RSS News Item through Evolution

The good part is that my actual data is always independent of such MUAs. Tomorrow, as technology - trends - economics evolve, something new would come as a replacement but my data would still be mine.

Mobile trends Trends have shown. Data mobility is a commodity expectation now. As such, I wanted to have something fill in that gap for me. So that I could access my information - which I ve preferred in a format - easily in today s trendy options. I tried multiple options on my current preferred platform of choice for mobiles, i.e. Android. Finally I came across Aqua Mail, which fits in most of my requirements. Aqua Mail does

• Connect to my laptop over imap
• Can sync the requested folders
• Can sync requested data for offlince accessibility
• Can present the synchronized data in a quite flexible and customizable manner, to match my taste
• Has a very extensible User Interface, allowing me to customize it to my taste

Pictures can do a better job of describing my english words.

Aqua Mail Message List Interface

Aqua Mail Message View Normal

Aqua Mail Message View Zoomed - Fit to Screen

All of this done with no dependence on network connectivity, post the sync. And all information is stored is best possible simple format.

One of the things that I found most vexing about lockdown was that I was unable to play some of my favourite board games. There are online systems for many games, but not all. And online systems cannot support games like Mao where the players make up the rules as we go along. I had an idea for how to solve this problem, and set about implementing it. The result is Otter (the Online Table Top Environment Renderer). We have played a number of fun games of Penultima with it, and have recently branched out into Mao. The Otter is now ready to be released! More about Otter (cribbed shamelessly from the README) Otter, the Online Table Top Environment Renderer, is an online game system. But it is not like most online game systems. It does not know (nor does it need to know) the rules of the game you are playing. Instead, it lets you and your friends play with common tabletop/boardgame elements such as hands of cards, boards, and so on. So it s something like a tabletop simulator (but it does not have any 3D, or a physics engine, or anything like that). This means that with Otter:

• Supporting a new game, that Otter doesn t know about yet, would usually not involve writing or modifying any computer programs.
• If Otter already has the necessary game elements (cards, say) all you need to do is write a spec file saying what should be on the table at the start of the game. For example, most Whist variants that start with a standard pack of 52 cards are already playable.
• You can play games where the rules change as the game goes along, or are made up by the players, or are too complicated to write as a computer program.
• House rules are no problem, since the computer isn t enforcing the rules - you and your friends are.
• Everyone can interact with different items on the game table, at any time. (Otter doesn t know about your game s turn-taking, so doesn t know whose turn it might be.)

Installation and usage Otter is fully functional, but the installation and account management arrangements are rather unsophisticated and un-webby. And there is not currently any publicly available instance you can use to try it out. Users on chiark will find an instance there. Other people who who are interested in hosting games (of Penultima or Mao, or other games we might support) will have to find a Unix host or VM to install Otter on, and will probably want help from a Unix sysadmin. Otter is distributed via git, and is available on Salsa, Debian's gitlab instance. There is documentation online. Future plans I have a number of ideas for improvement, which go off in many different directions. Quite high up on my priority list is making it possible for players to upload and share game materials (cards, boards, pieces, and so on), rather than just using the ones which are bundled with Otter itself (or dumping files ad-hoc on the server). This will make it much easier to play new games. One big reason I wrote Otter is that I wanted to liberate boardgame players from the need to implemet their game rules as computer code. The game management and account management is currently done with a command line tool. It would be lovely to improve that, but making a fully-featured management web ui would be a lot of work. Screenshots! (Click for the full size images.)

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I ve been experimenting with IMA/EVM. Here is the Sourceforge page for the upstream project [1]. The aim of that project is to check hashes and maybe public key signatures on files before performing read/exec type operations on them. It can be used as the next logical step from booting a signed kernel with TPM. I am a long way from getting that sort of thing going, just getting the kernel to boot and load keys is my current challenge and isn t helped due to the lack of documentation on error messages. This blog post started as a way of documenting the error messages so future people who google errors can get a useful result. I am not trying to document everything, just help people get through some of the first problems. I am using Debian for my work, but some of this will apply to other distributions (particularly the kernel error messages). The Debian distribution has the ima-evm-utils but no other support for IMA/EVM. To get this going in Debian you need to compile your own kernel with IMA support and then boot it with kernel command-line options to enable IMA, in recent kernels that includes lsm=integrity as a mandatory requirement to prevent a kernel Oops after mounting the initrd (there is already a patch to fix this). If you want to just use IMA (not get involved in development) then a good option would be to use RHEL (here is their documentation) [2] or SUSE (here is their documentation) [3]. Note that both RHEL and SUSE use older kernels so their documentation WILL lead you astray if you try and use the latest kernel.org kernel. The Debian initrd I created a script named /etc/initramfs-tools/hooks/keys with the following contents to copy the key(s) from /etc/keys to the initrd where the kernel will load it/them. The kernel configuration determines whether x509_evm.der or x509_ima.der (or maybe both) is loaded. I haven t yet worked out which key is needed when.

#!/bin/bash
mkdir -p $ DESTDIR /etc/keys
cp /etc/keys/* $ DESTDIR /etc/keys

Making the Keys

#!/bin/sh
GENKEY=ima.genkey
cat << __EOF__ >$GENKEY
[ req ]
default_bits = 1024
distinguished_name = req_distinguished_name
prompt = no
string_mask = utf8only
x509_extensions = v3_usr
[ req_distinguished_name ]
O =  hostname 
CN =  whoami  signing key
emailAddress =  whoami @ hostname 
[ v3_usr ]
basicConstraints=critical,CA:FALSE
#basicConstraints=CA:FALSE
keyUsage=digitalSignature
#keyUsage = nonRepudiation, digitalSignature, keyEncipherment
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid
#authorityKeyIdentifier=keyid,issuer
__EOF__
openssl req -new -nodes -utf8 -sha1 -days 365 -batch -config $GENKEY \
                -out csr_ima.pem -keyout privkey_ima.pem
openssl x509 -req -in csr_ima.pem -days 365 -extfile $GENKEY -extensions v3_usr \
                -CA ~/kern/linux-5.11.14/certs/signing_key.pem -CAkey ~/kern/linux-5.11.14/certs/signing_key.pem -CAcreateserial \
                -outform DER -out x509_evm.der

To get the below result I used the above script to generate a key, it is the /usr/share/doc/ima-evm-utils/examples/ima-genkey.sh script from the ima-evm-utils package but changed to use the key generated from kernel compilation to sign it. You can copy the files in the certs directory from one kernel build tree to another to have the same certificate and use the same initrd configuration. After generating the key I copied x509_evm.der to /etc/keys on the target host and built the initrd before rebooting.

[    1.050321] integrity: Loading X.509 certificate: /etc/keys/x509_evm.der
[    1.092560] integrity: Loaded X.509 cert 'xev: etbe signing key: 99d4fa9051e2c178017180df5fcc6e5dbd8bb606'

Errors Here are some of the kernel error messages I received along with my best interpretation of what they mean. [ 1.062031] integrity: Loading X.509 certificate: /etc/keys/x509_ima.der
[ 1.063689] integrity: Problem loading X.509 certificate -74 Error -74 means -EBADMSG, which means there s something wrong with the certificate file. I have got that from /etc/keys/x509_ima.der not being in der format and I have got it from a der file that contained a key pair that wasn t signed.

[    1.049170] integrity: Loading X.509 certificate: /etc/keys/x509_ima.der
[    1.093092] integrity: Problem loading X.509 certificate -126

Error -126 means -ENOKEY, so the key wasn t in the file or the key wasn t signed by the kernel signing key.

[    1.074759] integrity: Unable to open file: /etc/keys/x509_evm.der (-2)

Error -2 means -ENOENT, so the file wasn t found on the initrd. Note that it does NOT look at the root filesystem. References

• [1] https://sourceforge.net/p/linux-ima/wiki/Home/
• [2] https://tinyurl.com/yfvhqdjr
• [3] https://en.opensuse.org/SDB:Ima_evm