From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Paul Fontenot" <paul@pitbull-racing.com>
Subject: Groups in iptables
Date: Sat, 29 Nov 2003 10:18:30 -0700
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I would imagine the answer to this is yes, but I haven't found anything on
the subject. If you wanted to limit outbound traffic for a certain port to
certain group of servers is that possible?

For example, can I create a group:

MAILSERVERS = 192.168.0.25, 192.168.0.26, 192.168.0.27

and use that in a ruleset:
-A INSIDE_ACCESS_OUT -s $MAILSERVERS -p tcp -m tcp --dport 25 --tcp-flags
SYN,RST,ACK SYN -j ACCEPT

and then drop the rest:
-A INSIDE_ACCESS_OUT -p tcp -m tcp --dport 25 -j DROP