TCP option 19, MD5 signature

Description Glossary RFCs Publications Obsolete RFCs


Protocol suite: TCP/IP.
Protocol type:Transport layer protocol.
Option length:18 bytes.
Host implementation:
Router implementation:
Links: IANA: TCP option numbers.

RFC 2385, pg 1:

This memo describes a TCP extension to enhance security for BGP. It defines a new TCP option for carrying an MD5 [RFC 1321] digest in a TCP segment. This digest acts like a signature for that segment, incorporating information known only to the connection end points. Since BGP uses TCP as its transport, using this option in the way described in this paper significantly reduces the danger from certain security attacks on BGP.

MAC header IP header TCP header TCP option 19 Data

TCP Option 19:

00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
Kind Length
MD5 Digest

Kind. 8 bits. Set to 15.

Length. 8 bits. Set to 18.

MD5 Digest. 16 bytes.



[RFC 2385] Protection of BGP Sessions via the TCP MD5 Signature Option.


Obsolete RFCs:

Description Glossary RFCs Publications Obsolete RFCs