Extensible Authentication Protocol (EAP) - (IETF RFC 2284) an extension to PPP that supports several different authentication methods, L. Blunk, J. Vollbrecht, March 1998
Layer Two Tunneling Protocol (L2TP) - facilitates the tunneling of PPP packets across an intervening network in a way that is as transparent as possible to both end-users and applications
Securing L2TP using IPsec - (IETF RFC 3193) discusses how L2TP may use IPsec to provide for tunnel authentication, privacy protection, integrity checking and replay protection B. Patel, B. Aboba, W. Dixon, G. Zorn, S. Booth, November 2001
OpenSSH - free version of the SSH suite of network connectivity tools
OpenSSL - collaborative effort to develop an open-source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library
Point-to-Point Tunneling Protocol (PPTP) - for creating Virtual Private Networks (VPNs), Ascend Communications, Microsoft Corporation, U.S. Robotics, 3Com Corporation, ECI Telematics, June 1996
Secure Multipurpose Internet Mail Extensions (S/MIME)
Domain Security Services using S/MIME - (IETF RFC 3183) describes how S/MIME can be processed and generated by a number of components of a communication system, such as message transfer agents, guards and gateways to deliver security services, collectively referred to as 'Domain Security Services,' T. Dean, W. Ottaway, October 2001
Secure Shell (SSH) and Secure Shell (secsh) - the secsh working group is attempting to update and standardize SSH, which provides encryption to otherwise unsecure mechanisms such as telnet and ftp, providing remote logins, file copying, and tunneling
The Secure HyperText Transfer Protocol (S-HTTP) - (IETF RFC 2660) provides independently applicable security services for transaction confidentiality, authenticity/integrity and non-repudiability of origin for messages sent using the hypertext transfer protocol (HTTP), E. Rescorla, A. Schiffman, August 1999
Terminal Access Controller Access Control System (TACACS) - (IETF RFC 1492) authentication protocol previously common to UNIX networks that allows a remote access server to forward a user's logon password to an authentication server to determine whether access can be allowed to a given system, has generally been replaced by TACACS+ or RADIUS, C. Finseth, July 1993
Transport Layer Security (TLS) - IETF effort to provide security features at the transport layer, rather than general purpose security and key management mechanisms