>From: bret @
com (Bret McDanel)
>To: firewalls @
>Subject: RFC question
>I am looking for a RFC (or anyother source) that has info
>about the format and all for an IP packet.. What I need is
>to know how many bytes the header of the packet is and what
>those bytes mean (ie what data gets stuffed in em)..
>From RFC1392 ( Internet Users' Glossary ) :
Internet Protocol (IP)
The Internet Protocol, defined in STD 5, RFC 791, is the network
layer for the TCP/IP Protocol Suite. It is a connectionless,
best-effort packet switching protocol. See also: packet
switching, Request For Comments, TCP/IP Protocol Suite.
The URL you want is:
It makes for kinda dry reading though (all 362 pages of it).
If you have the cash I'd recommend getting Sidnie Feit's "TCP/IP"
and/or W. Richard Stevens' "TCP/IP Illustrated Vol. 1" books instead
(Disclaimer: I know both authors, but that is not why I'm steering
you towards them. Honest.).
NB. STD 5 only describes the current IPv4. It doesn't go into the new
proposed standard for IPv6 (aka IP "The Next Generation", aka SIPP-16).