This document discusses implementation techniques for using IP Protocol/Payload number 4 Encapsulation for tunneling with IP Security and other protocols. This memo provides information for the Internet community. It does not specify an Internet standard. This document describes the use of keyed SHA with the IP Authentication Header. This document defines an Experimental Protocol for the Internet community. This document describes the Triple DES-CBC security transform for the IP Encapsulating Security Payload (ESP). This document defines an Experimental Protocol for the Internet community.