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Paul Jakma
124 followers -
Linux, tech, ILUG, computer networking/routing, bicycles, MotoGP, etc...
Linux, tech, ILUG, computer networking/routing, bicycles, MotoGP, etc...

124 followers
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♥ cycling
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26/01/2017
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So, even GNOME Classic/Fallback has been shellified in recent GNOME3 releases. Used to be Classic was still using metacity and a stripped down GNOME2 panel, but now it's a "skin" of gnome-shell. With all the performance annoyances that brings when you mix a 3D compositing window-manager partly implemented in javascript, with any video and reverse engineered NVidia drivers. Sigh.

I think it's time to move to a simpler window manager for my workstation. Back to Window Maker it is! I even still had my original configs lying around - timestamp on the dir was '99! :)
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When you're in a dracut initramfs emergency shell with no job control cause of an fsck issue, and that one inode with a flag it shouldn't have turns into a seemingly endless list of them.

I eventually gave up and hit reset. Even the fsck -y the next time still took tens of minutes to run. 
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Someone seems to be quite excited about Yes. #indyref
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In case anyone is interested in using GNU Octave / MatLab to do distance calculations in adjacency matrices for graphs. Very interested how to speed these up, if anyone knows. #octave   #graphs   #shortestpath  

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Networking WTF of the day:
So this is interesting (to TCP geeks).

+John Looney noticed that:

    while true; do telnet localhost 50000; done

will eventually succeed in connecting (nothing's listening on port 50000), and, strangely, it connects to itself. What's happening is that the ephemeral port allocated for the socket source is actually accepting the connection, resulting in a self connect.

Even more interestingly; if you have two machines, and arrange matters so that each connects to the other using the other's source address as their target address, the connection is established. This can be shown using socat as follows:

    On machine A: socat stdio TCP:B:50000,sourceport=50001
    On machine B: socat stdio TCP:A:50001,sourceport=50000

+Kevin Lyda and +Paul Jakma did some further investigation, and it looks like this is how the "simultaneous connection synchronisation" of TCP works - see figure 8 of RFC793. General opinion of the systems administration people I've shown this to is "WITCHCRAFT!"

Your Interesting Network Thing Of The Day.

For your next task: figure out how to make this into a connection-interception hack. Easiest to achieve on localhost due to the size of the address:port space, but still...

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Not sure how you end up with NaN here...
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