Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!ESOC.BITNET!ESC1814
From: ESC1814@ESOC.BITNET
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Smart filtering within a protocol on bridge/router?
Message-ID: <8911220607.AA01890@ucbvax.Berkeley.EDU>
Date: 22 Nov 89 06:07:47 GMT
References: <aecom!glen@UUNET.UU.NET>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: ESOC - European Space Operations Centre
Lines: 13
X-Unparsable-Date: Mon, 20 Nov 89 14:24:51 SET


Using the Cisco router extended access-list feature you can filter IP
connections according to Source and Destination address, protocol ie.
IP, TCP, UDP, & ICMP, and down to the port number/service access point.

You can use >, <, or == or != operators to specify which port(s) may be
accessed. eg to allow only mail connections you could restrict a connection
between hosts to port 25 (SMTP port)

Dave Stafford
European Space Operations Centre
Darmstadt,
W. Germany