Security Considerations

   There are many security issues in the communication layers of host
   software, but a full discussion is beyond the scope of this RFC.

   The Internet architecture generally provides little protection
   against spoofing of IP source addresses, so any security mechanism
   that is based upon verifying the IP source address of a datagram
   should be treated with suspicion.  However, in restricted
   environments some source-address checking may be possible.  For
   example, there might be a secure LAN whose gateway to the rest of the
   Internet discarded any incoming datagram with a source address that
   spoofed the LAN address.  In this case, a host on the LAN could use
   the source address to test for local vs. remote source.  This problem
   is complicated by source routing, and some have suggested that
   source-routed datagram forwarding by hosts (see Section 3.3.5) should
   be outlawed for security reasons.

   Security-related issues are mentioned in sections concerning the IP
   Security option (Section 3.2.1.8), the ICMP Parameter Problem message
   (Section 3.2.2.5), IP options in UDP datagrams (Section 4.1.3.2), and
   reserved TCP ports (Section 4.2.2.1).

Author's Address

   Robert Braden
   USC/Information Sciences Institute
   4676 Admiralty Way
   Marina del Rey, CA 90292-6695

   Phone: (213) 822 1511

   EMail: Braden@ISI.EDU