There is a classic TCP interception problem where an active TCP attack can be done. This experimental implementation is designed to prevent that. Service can be encrypted and signed or just signed. Service can be one-way or two-way, or best-effort. IDEA encryption is used and is implemented in SunOS 4.1.3.
In this implementation, four bytes are reserved are used to point to the key in the header (the header is longer than normal).TCPCRYPT uses protocol number 254.
Sofware will be available soon.