Micro Tetris™

December 26, 2021 - 1 min read

Micro Tetris — one of the smallest Tetris implementations in the world! Utilizing only ANSI escape sequences to draw the board, no external library dependencys other than a standard C-library, like uClibc or musl libc. Hence, it is very suitable for small embedded devices in need of an easter egg ;-) The game is based on a 1989 International Obfuscated C Code Contest (IOCCC) entry made by John Tromp.

HowTo: Set up Merecat with cgit

December 9, 2021 - 2 mins read

merecat

This post details how to set up cgit with Merecat httpd. It began as a GitHub issue report by Mr Alok G. Singh, who had run into problems setting it up, and ended up as a HowTo.

HowTo: Set up Merecat with Ikiwiki

December 9, 2021 - 1 min read

merecat

This is a HowTo for setting up ikiwiki with Merecat httpd. First install ikiwiki $ sudo apt install ikiwiki libcgi-session-perl libcgi-formbuilder-perl Follow the steps to setup a new Wiki or Blog. In this example we set up a wiki in our ~/public_html: $ ikiwiki --setup /etc/ikiwiki/auto.setup ... Successfully set up wiki: url: http://localhost/~jocke/wiki srcdir: ~/wiki destdir: ~/public_html/wiki repository: ~/wiki.git To modify settings, edit ~/home.setup and then run: $ ikiwiki --setup ~/home.

The original multicast routing daemon

November 3, 2021 - 2 mins read

mrouted is an implementation of the IPv4 multicast routing protocol DVMRP, RFC 1075. It is capable of turning a UNIX workstation, or Linux device, into a multicast router with tunneling support. Tunneling may be required to cross non-multicast-aware routers. The Distantance Vector Multicast Routing Protocol (DVMRP), derived from RIP, is suitable for smaller/dense networks. It employs the “flood and prune” method, where multicast is flooded until neighboring routers opt out from unwanted multicast groups.

HowTo: Build & Use My Projects

Joachim Wiberg - October 5, 2021 - 5 mins read

Ever so often someone new to Open Source show up on GitHub or in my inbox. It usually starts something like this:

“Hey, I just downloaded your software, what’s next?”
“Your software doesn’t work on my system!!!!”
“How can I do that weird-thing that fits my odd use-case?”
“I have zero documented experience but I think you should fix your build system!”

This HowTo is for you.

0. Short Version

Download a versioned archive from the project’s Releases page
Extract archive for v1.2.3 and change to its directory, cd archive-1.2.3/
./configure --help, or use something like the following …
./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var && make && sudo make install

Some projects of mine are available in Debian/Ubuntu/FreeBSD, if you use that, please report bugs to them and not me. I have no control over what they do.

Cheers
/Joachim

smcroute.conf example

August 19, 2021 - 3 mins read

# # smcroute.conf example # # The configuration file supports joining multicast groups, to use # Layer-2 signaling so that switches and routers open up multicast # traffic to your interfaces. Leave is not supported, remove the # mgroup and SIGHUP your daemon, or send a specific leave command. # # NOTE: Use of the mgroup command should be avoided if possible. # Instead configure "router ports" or similar on the switches # or bridges on your LAN.

HowTo: Add Multicast Routing to FreeBSD kernel

August 1, 2021 - 1 min read

This is a very short blog post, mostly intended as a reminder to myself. Basically, there are two methods of adding multicast routing support to the FreeBSD kernel: Rebuild the kernel with options MROUTING Load the kernel module: kldload ip_mroute The kernel rebuild assumes the src.txz set was installed previously. cd /usr/src cd sys/amd64/conf cat GENERIC | sed 's/GENERIC$/MULTICAST/' > MULTICAST echo 'options MROUTING # Multicast routing' >> MULTICAST echo 'options PIM # Enable for pimd' >> MULTICAST cd - make kernel KERNCONF=MULTICAST reboot That’s it.

N E M E S I S

July 7, 2021 - 3 mins read

Nemesis is a command-line network packet crafting and injection utility for UNIX-like and Windows systems. Well suited for testing Network Intrusion Detection Systems, firewalls, IP stacks and a variety of other tasks. As a command-line driven utility, it is perfect for automation and scripting. Nemesis can natively craft and inject ARP, DNS, ETHERNET, ICMP, IGMP, IP, OSPF, RIP, TCP and UDP packets. Using the IP and the Ethernet injection modes, almost any custom packet can be crafted and injected.

Emacs: GMail and Lore Mailing Lists

May 11, 2021 - 4 mins read

With lots of help from the tireless Tobias Waldekranz, I think I’ve finally found the perfect “magit like” email setup. With Emacs, of course. This is the story of how I did it. First install notmuch, mbsync (from the isync package), and afew: sudo apt install notmuch isync afew Do initial setup of notmuch for your user. I’ve opted to store my mail in ~/mail, this is used throughout the text below, ymmv.

Dependency handling in Finit

May 1, 2021 - 2 mins read

This is a blog post about Finit. Each post is concluded with a video summarizing the topic. The impatient reader can scroll down to the video.

Most non-trivial systems require dependency tracking between services. Not only does it help ensure correct operation, it is also an enabler for starting services in parallel. Less known, but just as important, is handling dependencies at system reconfiguration.