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Re: insight on S10 ipfilter patch 125014-02?

To: "Jeff A. Earickson" <jaearick@colby.edu>
Subject: Re: insight on S10 ipfilter patch 125014-02?
From: Carson Gaspar <carson@taltos.org>
Date: Tue, 06 Mar 2007 08:54:39 -0800
Cc: ipfilter@coombs.anu.edu.au
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Jeff A. Earickson wrote:
Darren,

If I change my port 25 rule from:

pass in quick proto tcp from any to 137.146.28.72 port = 25 flags S keep state keep frags pass out quick proto tcp from 137.146.28.72 to any port = 25 flags S keep state keep frags

to:

pass in  quick proto tcp from any to 137.146.28.72 port = 25
pass out quick proto tcp from 137.146.28.72 to any port = 25

Then all/most of my email traffic halts.  I am using Sun multipathing,

If you want stateless rules, then you need to allow reply packets, which you haven't done. Try the following (syntax from memory, so...):

pass out quick proto tcp from 137.146.28.72 to any port = 25
pass in quick proto tcp from any port = 25 to 137.146.28.72 port > 32767 flags A/A
pass in  quick proto tcp from any to 137.146.28.72 port = 25
pass out quick proto tcp from 137.146.28.72 port = 25 to any port > 1023 flags A/A

You'll note that the inbound rule is more restrictive with ports. You've said you're running Solaris, so the anonymous port range is 32768-65535 (unless you've changed it). The Internet has a much broader range of anonymous ports (but always >= 1024, in my experience). Personally, I'd get rid of the outbound ACK rule port restriction entirely, unless you have naughty users running things on your mail server...

--
Carson

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