Security Basics mailing list archives
RE: TCP/IP CRC question
From: "Shaineel Singh" <ssingh () kbs net au>
Date: Thu, 7 Oct 2004 08:20:17 +1000
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 While the CRC in the data field would be to ensure integrity the FCS field is there to safeguard against collision, etc Have a read of this for a better explanation http://support.3com.com/infodeli/tools/netmgt/tncsunix/product/091500/ c11ploss.htm Shaineel Singh p: +61 422 921 951 e: mailto:ssingh () kbs net au w: http://203.220.32.126/~ssingh/ pgp: 91AC 0F02 B206 36F9 F414 D1EE 8545 94F0 7804 A1EF - -----Original Message----- From: Jorge Mendez Bonini [mailto:jlmb () cableonda net] Sent: Wednesday, 6 October 2004 4:15 PM To: security-basics () securityfocus com Subject: TCP/IP CRC question I've been reading about the TCP/IP protocol stack (TCP/Ilustrated Vol1 by Richard Stevens) lately and since Ethernet is quite common nowadays almost all link layer examples refer to it (I also checked Douglas Comer Internetworking with TCP/IP vol1). I tried searching RFC but found it very time consuming without good results (maybe I'm not used to it...yet) The Ethernet Frame contains a field known as FCS which contains a CRC. Now, my question is: If the CRC is generated from DATA field among others, What's the point of using checksums on the upper protocolos (IP checksums etc..)? Thanks for your time. -----BEGIN PGP SIGNATURE----- Version: PGP 8.1 iQA/AwUBQWRvoIVFlPB4BKHvEQLywACeObmHCrvydN9UvHtwXkw3r+x2v1MAoKWx WgrJgDDIYzJpHHoyG/bSB3PP =AugW -----END PGP SIGNATURE-----
Current thread:
- TCP/IP CRC question Jorge Mendez Bonini (Oct 06)
- RE: TCP/IP CRC question David Gillett (Oct 07)
- Re: TCP/IP CRC question Jonathan Loh (Oct 07)
- RE: TCP/IP CRC question Shaineel Singh (Oct 07)
- Re: TCP/IP CRC question Alex V . Lukyanenko (Oct 07)
- Re: TCP/IP CRC question Fernando Gont (Oct 07)
- RE: TCP/IP CRC question Shaineel Singh (Oct 07)
- Re: TCP/IP CRC question Ansgar -59cobalt- Wiechers (Oct 07)
- Re: TCP/IP CRC question Fernando Gont (Oct 07)
- Re: TCP/IP CRC question Miles Stevenson (Oct 07)
- Re: TCP/IP CRC question Miles Stevenson (Oct 08)
- RE: TCP/IP CRC question Clement Dupuis (Oct 12)
- Re: TCP/IP CRC question Miles Stevenson (Oct 08)
- <Possible follow-ups>
- Re: TCP/IP CRC question Don Parker (Oct 07)
- RE: TCP/IP CRC question Ted A (Oct 07)
(Thread continues...)