13. Security

TCP/IP makes universal interoperability possible. However, in many environments, administrators need to limit this interoperability to protect private data. These restrictions correspond to the general problem of security, but the Internet is more difficult to make secure than a simple computer, because it offers much more powerful communication services. The problem is how a user relying on TCP/IP can ensure that his machines and data are protected against unauthorized access.

A working group has explored the issue of secure messaging by experimenting with an enhanced private messaging service. The idea is to implement a mechanism that enables the sender to encrypt his message and send it over the open Internet without allowing anyone other than the recipient to decrypt it.

Work on packet filtering in gateways has produced a variety of...