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Date:      Tue, 22 Apr 2003 12:48:29 -0400
From:      "The Jetman" <>
To:        "FBSD IPFW" <>
Subject:   [Q2-4.8-R] Can Anyone Help With Questions About MAC Filtering and IPFW2 ?
Message-ID:  <>

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    I'm using 4.8-RELEASE to implement MAC-filtering bridge for my
wireless network.  Altho I am relatively new w/ FBSD (since Apr '02),
I've been getting the desired results writing my own rules for IPFW.  My
1st attempt w/ IPFW2 was successful, but I can't figure out why !  dc0
is the incoming (the anonymous one, w/o an IP addr) interface.

00100 allow ip from any to any MAC any a:b:c:d:e:f in via dc0
00200 allow ip from any to any MAC a:b:c:d:e:f any out via dc0
00300 allow ip from any to any MAC b:c:d:e:f:g any in via dc0
00400 allow ip from any to any MAC any b:c:d:e:f:g out via dc0
00500 deny log ip from any to any MAC any any in via dc0
00600 allow ip from any to any
65535 allow ip from any to any

    Only rules 100, 200, 500, and 600 fire.  Rules 100 and 200 fire for obvious
reasons (bec they match the patterns I've anticipated.)  Bec of how IP-based
IPFW1 rules work, I *thought* one would have to have matching inbound/outbound
rules WRT to MAC filtering.  What's most baffling is that non-approved
MAC addrs are blocked as desired [at rule 500] as hoped, but legal traffic is
permitted back thru the bridge to its sender [via rule 600.]  WHY ????  I'm only
showing the simplest example of the scripts I've been experimenting with.  I've
got other scripts that do permit other MACs thru the bridge (either wireless of
Ethernet) while blocking everyone else, so I'm very close to what I want.

    My principal concern is that I don't rely on bogus (ie. broken) behavior
of IPFW2, only to discover at some unspecified time in the future, this
was never really working and my LAN was never really protected.  Or worse
still, after I start making the script more complex, something unrelated goes
wrong.  The only help I've been able to find is a single site, where a guy
showed his 1st effort at an IPFW2 script, intending to do the same thing I'm
trying to do.  I used his 1st script, as a starting place for my efforts.
this, I haven't been able find any other instructive refs to IPFW2 on the web
or in the FBSD mail list archives.


===============  From the desk of Jethro Wright, III  ================
+  Never attribute to malice that which is adequately explained by   +
+  incompetence.                                                     +
===  =====================  Hanlon's Razor  ===

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