The charter of this IETF group developing mechanisms to protect client protocols of IP.

Internet privacy and encryption information and protocols.

An IPsec reference implementation for Linux.

IPSec VPN configuration information.

An IETF group working on PPP's extensions.

PPTP technical specification by 3Com.

PPTP server solution for Linux. Includes downloads, documentation and news.

A Linux, FreeBSD and NetBSD client for the Microsoft Point-to-Point Tunneling Protocol.

Counterpane Systems has exposed insecurities in Microsoft's Point to Point Tunneling Protocol.

A GNU program allowing to encrypt arbitrary TCP connections inside Secure Sockets Layer (SSL).

Technologies used for creating secure VPNs. Various standards and protocols listed with links to related RFCs.