CCProxy - Want to share Internet connection? Get every computer online through a single Internet connection?
PowerDNS - PowerDNS offers open source DNS software, services, and support.
Apache Traffic Server - Fast, scalable and extensible HTTP/S 2 and 1.1 compliant caching proxy server.
dnsmasq - Dnsmasq is a lightweight, easy to configure DNS forwarder and DHCP server.
FreeProxy - Feature summary from website:* Internet connection sharing with demand dialling
Unbound - Unbound is a validating, recursive, and caching DNS resolver.