Tag Archives: english

NMEA2000 and CANbus

I’ve been looking at NMEA2000 and CANbus lately. I’m attempting to reverse engineer the binary protocol seen coming out of the USB port on a Garmin GND10 network bridge, and that opens a whole field of new and interesting stuff … Continue reading

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PROXY protocol in Varnish

Dag has been working implementing support for HAProxy’s PROXY protocol[1] in Varnish. This is a protocol adds a small header on each incoming TCP connection that describes who the real client is, added by (for example) an SSL terminating process. … Continue reading

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Disable Spotify song change notification in Debian Linux

Recently Spotify started sending notifications to the desktop on song change. This is unnecessarily annoying and breaks my flow, so it had to go. (and since I usually just listen to the same playlists anyway, I’m very well aware what … Continue reading

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What happened to ban.url in Varnish 4.0?

tl;dr; when using Varnish 4 and bans via varnishadm, instead of “ban.url EXPRESSION”, use “ban req.url ~ EXPRESSION”. In Varnish 3.0 we had the ban.url command in the varnishadm CLI. This was a shortcut function expanding to the a bit cryptic (but powerful) … Continue reading

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Varnish Cache development news

Short update on activities in Varnish cache development: Work is being done on getting access to the request BODY inside Varnish. This feature has been requested for a while, particularly by the security.vcl guys. See daf0e2c. The 2013Q1 Varnish Developer Day will … Continue reading

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Varnish trick: Serve stale content while refetching

Here is a small trick we recently implemented for a customer: The main premise was: No clients should have to wait while the backend works. If a request is a miss, give the client a slightly stale/old page instead, and fetch … Continue reading

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New Varnish VMOD: Softer purges / invalidations

With the new softpurge vmod you can do cache invalidation in Varnish that only affects objects if your backend is up. This means that you can purge all you want, and in the normal case everything works as expected, but if … Continue reading

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Varnishncsa and std.log()

New in Varnish 3.0.3rc1 is that you can put arbitrary log lines from VCL into the varnishncsa output. This can be used for funky stuff like logging the session cookie along with the request. Let’s say you have the following … Continue reading

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Detecting IP-over-DNS, part two.

As mentioned earlier, I did some work on detecting IP-over-DNS traffic as a part of my masters degree from NTNU in Communication Technology with focus on information security. My final method was to, and this may be cheating, look at … Continue reading

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Detecting IP-over-DNS

I wrote my master’s thesis at the Norwegian University of Science and Technology (NTNU) during the spring of 2010. My assignment was “Covert channels in the Domain Name System”, but for the most part it is about detecting an IP-over-DNS … Continue reading

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