CIPE - An ongoing project to build encrypting IP routers. Software is already available for Linux and released under GPL.
GNU Zebra - Manages TCP/IP based routing protocols. It supports BGP4 (RFC1771), RIPv1, RIPv2 and OSPFv2. Zebra makes use of OS threads where available.
NextHop - Makers of GateD, routing software that runs on a PC
Unofficial GNU Zebra FAQ - GNU Zebra documentation, not included into releases, but useful and up-to-date. General dynamic routing information included.
