Date: Mon, 03 Apr 2000 11:03:48 -0500 From: Keith Ray <rayk@sugar-land.spc.slb.com> To: freebsd-security@FreeBSD.ORG Subject: ipfw dynamic rules & tcp rst Message-ID: <4.3.1.2.20000403104253.00af9380@163.188.48.51>
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I have been using the new dynamic ipfw rules in 4.0. I wanted to make the
firewall react as though it didn't exist by returning TCP RSTs instead of
just dropping the connection. However, the following rules do not work:
00400 check-state
00500 reset tcp from any to {myip} established
00600 reset tcp from {myip} to any established
00700 allow tcp from any to {myip} 22 keep-state setup
00800 reset tcp from any to {myip} setup
65535 deny ip from any to any
When a connection comes in for a non-allowed port, rule 800 rejects the
connection. However, rule 600 prevents the TCP RST from being sent and the
connection is dropped. The following rules work however:
00300 allow tcp from {myip} to any
00400 check-state
00500 reset tcp from any to {myip} established
00600 allow tcp from any to {myip} 22 keep-state setup
00700 reset tcp from any to {myip} setup
65535 deny ip from any to any
This time the connection is rejected and rule 300 allows the RST to be
sent. Is there a better way of accomplishing this?
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