Zeroshell is a Linux based distribution dedicated to the implementation of Router and Firewall Appliances completely administrable via web interface
The BIRD project aims to develop a fully functional dynamic IP routing daemon primarily targeted on (but not limited to) Linux, FreeBSD and other UNIX-like systems and distributed under the GNU General Public License.
Quagga is a routing software suite, providing implementations of OSPFv2, OSPFv3, RIP v1 and v2, RIPng and BGP-4 for Unix platforms, particularly FreeBSD, Linux, Solaris and NetBSD. Quagga is a fork of GNU Zebra which was developed by Kunihiro Ishiguro.
XORP is the industry’s only extensible open source routing platform. XORP provides a fully featured platform that implements IPv4 and IPv6 routing protocols and a unified platform to configure them
FRRouting (FRR) is an IP routing protocol suite for Linux and Unix platforms which
includes protocol daemons for BGP, IS-IS, LDP, OSPF, PIM, and RIP.
OPNsense is an open source, easy-to-use and easy-to-build FreeBSD based firewall and routing platform
The pfSense project is a free network firewall distribution, based on the FreeBSD operating system with a custom kernel and including third party free software packages for additional functionality.
VyOS is an open source network operating system that can be installed on physical hardware or a virtual machine on your own server, or a cloud platform . It is based on GNU/Linux and joins multiple applications such as Quagga, ISC DHCPD, OpenVPN, StrongS/WAN and others under a single management interface.
B.A.T.M.A.N. (better approach to mobile ad-hoc networking) is a routing protocol for multi-hop ad-hoc mesh networks.
OpenBGPD is a FREE implementation of the Border Gateway Protocol, Version 4. It allows ordinary machines to be used as routers exchanging routes with other systems speaking the BGP protocol.