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