Static Multicast Routing Daemon

SMCRoute is a daemon and command line tool to manipulate the multicast routing table in the UNIX kernel. Both FreeBSD and Linux kernels are supported, but it may work on other systems as well.

SMCRoute can be used as an alternative to dynamic multicast routing daemons like mrouted or pimd when (only) static multicast routes should be maintained and/or no proper IGMP signalling exists.

Features

  • Configuration file support, /etc/smcroute.conf
  • Support for restarting and reloading the .conf on SIGHUP
  • Source-less on-demand routing, a.k.a. (*,G) based static routing
  • Optional built-in mrdisc support, RFC4286
  • Support for multiple routing tables on Linux
  • Client with built-in support to show routes and joined groups

Why a Daemon?

A very common question is why smcroute must be a daemon? Why not just a simple tool, like ip route, for unicast routes?

The answer lies in how multicast is implemented in the UNIX kernel.

To be able to setup multicast routes a program must connect to the multicast routing socket in the kernel, when that socket is closed, which is done automatically when a UNIX program ends, the kernel cleans up all routes.

Problems? See the multicast howto

Origin & References

SMCRoute was originally written by Carsten Schill. Later on Julien Blache, Todd Hayton and Micha Lenk picked up development for Debian.

Since 2011 Joachim Nilsson heads development at GitHub. New features include config file support, reloading config on SIGHUP, source-less on-demand (*,G) routing, TTL scoping and support for disabling ALL interfaces except the few used for multicast routing.

Issue tracker and GIT repository available at GitHub, tarballs also available as .tar.gz for systems that do not have xz in the default install, like OpenBSD:

See also the OpenHub page, the Freshcode page, or the now dormant Free(code) page.