Subject: Inquiry on replay protection

From: Byung-Cheol Shin <[email-masked]>
Date: Sat, 09 Jan 1999 21:44:08 +0900

Hello:
  I read RFC2085, but I cannot undersrtand how to protect againt replay.

And I don't know how to get [ESP-DES-MD5].
Would anybody introduce to me  some document on the replay protection
for easy understanding?
  Thanks  in advance for the cooperations.

--
Shin, Byung-Cheol

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From: "Luis A. Sanchez" <[email-masked]>
Date: Tue, 12 Jan 1999 16:36:28 -0500 (EST)

Shin,

	In IPSec, both the AH [RFC2402] and ESP [RFC2406] protocols
contain an unsigned 32-bit sequence number field. This field is used
to protect against replay attacks. Appendix C of the IPSec
Architecture document [RFC2401] contains reference code that
implements a simple bitmask check on a 32-bit packet window.  RFC2085
is no longer applicable in the current IPSec architecture. You can
retrieve these documents from:

http://www.ietf.org/html.charters/ipsec-charter.html

Luis