/home/janfrode

Reviving my old blog from backups...

Spectrum Scale has support for end-to-end checksumming if you have an ESS, but not with non-ESS storage. As a poor man's checksumming, one can store file checksums in the extended attributes. Storing checksums here can be useful for validating if there has been bitrot at a later point, without leaving around .md5sum-files everywhere. Manually this can be done with the “mmchattr” command:

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I use Apache Traffic Server (ATS) as a reverse proxy, cache and SSL terminator for all* my publicly accessible web services.

If running this as fully separate containers, I would need to expose unique ports and do iptables mapping for each service. A simpler way of handling this is to run them all in the same POD. Then they can communicate on the loopback interface, and we only need to expose the publicly accessible port for ATS (443/tcp).

Initially only a container for writefreely and one for trafficserver will be running in the pod, but I have plans for more containers later. F.ex. I will need a container for simple file-hosting.

[*] All is currently only this blog, running WriteFreely. But I have immediate plans for a container for static file hosting, and there are lots of other ideas I need to look into at https://news.ycombinator.com/item?id=21235957 and https://www.reddit.com/r/selfhosted/

These were the steps I needed to perform to run pi-hole in a podman container on Centos8/RHEL8:

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I had the unifi controller running under debian, but finally re-softet my machine to run Centos-8 instead. Before doing that I made a backup of the Unifi controller.

After installing Centos-8 I tried setting up and running the unifi container from https://github.com/jdoss/unifi simply by running:

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Together with Miguel Gomez Gonzalez and Ahmad Y Hussein, I did an IBM Redbooks residency in Poughkeepsie, New York, to write a book about High-Performance computing on the IBM AC922 platform. In the book we try to document and share some insights about how to implement CORAL style HPC clusters. Download it from http://www.redbooks.ibm.com/abstracts/sg248422.html

Starting with OpenSSH v3.9 there was a new feature that allowed one to run several sessions over the same ssh connection. The benefit of connection sharing is that only the first time you connect to a host you'll need to exchange keys, authenticate, negotiate encryption, etc. Skipping all this initial connection setup, makes any additional sessions to a host you've already connected to very quick.

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Here's a port of http://www.cs.umd.edu/users/harry/jotp/ to Java 2 Platform Micro Edition (J2ME), so that it can be used on mobile phones that supports Java. I made this so that I can securely connect to our ssh-server from insecure internet cafees, where people might be trying to sniff my passsword. The midlet supports md5-hashing, since that's what I'm using. Adding md4 should be trivial, if anybody needs it.

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How to calculate CPUTime of a function with Java

I've wanted to know the cputime used in java functions, but it turned out that this was a bit too low level for java. Therefore I had to create a JNI (Java Native Interface) function for it. The code for this example is at http://tanso.net/CPUtest.tar.gz , and here's how to do it:

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