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Date:      Mon, 8 Jan 2001 13:01:05 -0500
From:      Vivek Khera <khera@kciLink.com>
To:        questions@freebsd.org
Subject:   ipfw fragments and connections to port 0
Message-ID:  <14938.97.366645.802181@onceler.kciLink.com>

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Every so often, I see something like this in my log files from ipfw:

ipfw: -1 Refuse TCP 63.252.242.78:0 204.117.82.12:0 in via fxp0

From what I understand, this is a connection to port 0, but I'm not
sure what that means, since port numbers start at 1.  Is this some
sort of attack or other kind of scan going on?

Also, occasionally I see this:

ipfw: -1 Refuse TCP 24.0.95.136 204.117.82.12 in via fxp0 Fragment = 184

What's that from, and do I need to take any corrective action?  These
are my rules, which are quite simple, and mainly to protect from snmp
snoops:

00100 allow ip from any to any via lo0
00200 deny ip from any to 127.0.0.0/8
00300 deny log udp from not 208.184.13.195 to 204.117.82.12 161,162
65535 allow ip from any to any

I'm on FreeBSD 4.1.1-STABLE on this particular box.  I haven't seen
any use of the "frag" keyword in the example I've seen in the various
docs, so I'm not sure how exactly to use it.

Thanks.

-- 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Vivek Khera, Ph.D.                Khera Communications, Inc.
Internet: khera@kciLink.com       Rockville, MD       +1-240-453-8497
AIM: vivekkhera Y!: vivek_khera   http://www.khera.org/~vivek/


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