OpenBSD VPN Mini-FAQ
- IPSec VPN configuration information.
- http://pintday.org/hack/docs/vpn-24-minifaq.shtml

NIST Cerberus
- An IPsec reference implementation for Linux.
- http://www.antd.nist.gov/tools/cerberus/

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

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

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

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

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

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

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