IP Security Protocol Working Group (IPSEC) The charter of this IETF group developing mechanisms to protect client protocols of IP. http://www.ietf.org/html.charters/ipsec-charter.html

Ipsec Internet privacy and encryption information and protocols. http://www.ipsec.dk

NIST Cerberus An IPsec reference implementation for Linux. http://snad.ncsl.nist.gov/cerberus/

OpenBSD VPN Mini-FAQ IPSec VPN configuration information. http://www.codetalker.com/greenbox/docs/vpn-24-minifaq.html

Point to Point Protocol Extensions Working Group (PPPEXT ) An IETF group working on PPP's extensions. http://www.ietf.org/html.charters/pppext-charter.html

PPTP Crack Counterpane Systems has exposed insecurities in Microsoft's Point to Point Tunneling Protocol. http://www.counterpane.com/pptp.html

Point to Point Tunneling Protocol PPTP technical specification by 3Com. http://infodeli.3com.com/infodeli/tools/remote/general/pptp/pptp.htm

Stunnel A GNU program allowing to encrypt arbitrary TCP connections inside Secure Sockets Layer (SSL). http://www.stunnel.org/

Layer 2 Tunnelling Protocol Daemon (L2TPd) History and information on this Protocol. http://www.l2tpd.org/

PoPToP PPTP server solution for Linux. Includes downloads, documentation and news. http://www.poptop.org/

PPTP Client A Linux, FreeBSD and NetBSD client for the Microsoft Point-to-Point Tunneling Protocol. http://pptpclient.sourceforge.net/

VPN-Protocols Technologies used for creating secure VPNs. Various standards and protocols listed with links to related RFCs. http://www.vpnc.org/vpn-standards.html

Tom Dunigan's Virtual Private Networks page This page describes IP-based VPN technology over the Internet http://www.csm.ornl.gov/~dunigan/vpn.html