Bugtraq mailing list archives
Re: Ambiguities in TCP/IP - firewall bypassing
From: Tony Finch <dot () dotat at>
Date: Sat, 19 Oct 2002 02:33:57 +0100
Alun Jones <alun () texis com> wrote:
Not necessarily. Have you heard of T/TCP? Before that was around, I remember hearing discussion of using a packet with SYN, FIN, and data all in one, to cut down on round-trips in really short communications, while still providing reliability.
One of the problems with T/TCP on the wider Internet is that it is almost as vulnerable to source address spoofing as UDP, so security facilities like those provided by tcp_wrappers (and built in to many daemons) are no longer so effective. With vanilla TCP, the T/TCP combination of SYN+ data+FIN isn't useful, because the passive end should discard data that arrives before the handshake is completed in order to preserve its spoof- resistence, therefore requiring a retransmit. Tony. -- f.a.n.finch <dot () dotat at> http://dotat.at/ FORTIES CROMARTY FORTH TYNE DOGGER: NORTHWESTERLY 4 OR 5, OCCASIONALLY 6. SHOWERS. GOOD.
Current thread:
- Ambiguities in TCP/IP - firewall bypassing Paul Starzetz (Oct 18)
- Re: Ambiguities in TCP/IP - firewall bypassing Alan DeKok (Oct 18)
- Re: Ambiguities in TCP/IP - firewall bypassing Benjamin Krueger (Oct 18)
- Re: Ambiguities in TCP/IP - firewall bypassing Alun Jones (Oct 18)
- RE: Ambiguities in TCP/IP - firewall bypassing John Fitzgerald (Oct 19)
- Re: Ambiguities in TCP/IP - firewall bypassing Tony Finch (Oct 19)
- Re: Ambiguities in TCP/IP - firewall bypassing Alan DeKok (Oct 18)
- Re: Ambiguities in TCP/IP - firewall bypassing Luis Bruno (Oct 19)
- Re: Ambiguities in TCP/IP - firewall bypassing Lyndon Nerenberg (Oct 21)
- Re: Ambiguities in TCP/IP - firewall bypassing Benjamin Krueger (Oct 18)
- Re: Ambiguities in TCP/IP - firewall bypassing Alan DeKok (Oct 18)
- Re: Ambiguities in TCP/IP - firewall bypassing cbrenton (Oct 19)
- Re: Ambiguities in TCP/IP - firewall bypassing Aaron Hopkins (Oct 19)
- Re: Ambiguities in TCP/IP - firewall bypassing Florian Weimer (Oct 22)