Category Archives: Solved Problems

Problems and solutions. Good stuff.

Using IPv6 SLAAC with IP forwarding on Debian Stretch (“connect: network is unreachable”, no default gateway)

When configured as a router, for instance for hosting virtual machines with KVM, a Debian machine with a somewhat recent kernel will not listen to router advertisements from others. This makes sense in many cases, but when you have a VM host in your internal network, which only router function is to allow communication to […]

Exim4 line length in Debian Stretch – “Mail delivery failed: returning message to sender”

Exim4 introducted new behaviour in the versions included in Debian Stretch. Suddenly, the RFC max line length of 998 characters is enforced, and emails with lines exceeding this length are returned to sender. For the interested, part of the discussion about this feature is over here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=839147 Anyway, the solution to this issue in Debian […]

Finding duplicate files with Bash

Someone recently asked, in #bash on Freenode, how to find duplicate files with Bash. Several options were suggested, and the user ended up installing and running “fdupes“. However, this sort of thing should be reasonably easy to do using “find” and a few pipes. As a quick overview, what you want to achieve is to […]

Cygwin for Windows XP – fast mirror

Cygwin stopped being compatible with Windows XP in 2016. Following this post on stackoverflow, you can find the setup files and a (very slow) mirror that’s compatible. I made my own, considerably faster, mirror of the last Windows XP compatible Cygwin release, at http://cygwinxp.cathedral-networks.org/ The mirror date is 2016-08-30, the 30th of August 2016 AD. […]

Killing a process tree, killing a PID and all children

Here are a couple of useful functions I wrote to kill a process tree. It’s useful when dealing with tcpserver, which refuses to disconnect a client for as long as a process it started, or a child of that process, still runs. It’s also good for tackling runaway unintentional fork bombs, rogue daemons and other […]

Making a telnet server with Bash and tcpserver

Telnet servers are everywhere. They are simple, insecure by nature, outdated, and often badly implemented. Let’s do that, shall we? 🙂 A simple way to make any command line interface listen to incoming TCP connections is tcpserver, provided as part of the ucspi-tcp or ucspi-tcp-ipv6 package on Debian. Using this, we can make any Bash […]

apt-get reports Packages not found

So.. this shit again. # apt-get update Ign http://ftp.debian.org jessie-updates InRelease Ign http://ftp.debian.org jessie-updates Release.gpg Ign http://ftp.debian.org jessie-updates Release Ign http://ftp.debian.org jessie-updates/main Sources/DiffIndex Ign http://ftp.debian.org jessie-updates/main i386 Packages/DiffIndex Ign http://ftp.no.debian.org jessie InRelease Ign http://ftp.no.debian.org jessie Release.gpg Ign http://ftp.no.debian.org jessie Release Ign http://ftp.no.debian.org jessie/main Sources/DiffIndex Ign http://ftp.no.debian.org jessie/main i386 Packages/DiffIndex Ign http://security.debian.org jessie/updates InRelease Ign http://security.debian.org […]