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Date:      Wed, 27 Nov 2002 21:00:54 +0100
From:      Borja Marcos <borjamar@sarenet.es>
To:        freebsd-stable@freebsd.org
Subject:   New ipfw+IPSEC behavior
Message-ID:  <200211272100.54796.borjamar@sarenet.es>

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=09Hello,

=09I have just upgraded from RELENG_4_7 to -STABLE and found a behavior c=
hange=20
between IPSec and IPFW.

=09The previous system did not apply IPFW rules to packets after being ex=
tracted=20
from a tunnel, and it seems that this behavior has changed.

=09I know that tunnels had a problem: you could not filter anything comin=
g=20
through the tunnel, but that behavior had some advantages. Perhaps a=20
compromise would be great.

=09In my case, I am using IPsec in a wireless network. Now I have two mac=
hines,=20
with one in hostap mode. The ipfw rules are configured like this:

add 200 allow udp from 192.168.2.0/24 500 to me 500 via wi0
add 210 allow udp from me 500 to 192.168.2.0/24 500 via wi
add 300 allow esp from 192.168.2.0/24 to me via wi0
add 310 allow esp from me to 192.168.2.0/24 via wi0
add 400 deny log all from any to any via wi0

=09This may seem odd, but it is very effective. It completely blocks traf=
fic=20
from the wi interface unless it is IKE traffic or ESP. The advantages?

=091 - A wardriver cannot "touch" your machine unless he/she can succesfu=
lly set=20
up a tunnel, guessing the IKE pre-shared key or exploiting a vulnerabilit=
y in=20
racoon.

=092 - You are protected from configuration errors. If, for whatever reas=
on,=20
unencrypted traffic "tries" to leave of reach the interface, it will not=20
pass. Moreover, you can see it in the system log.

=09Any ideas? It would be great to keep this behavior. Perhaps as an opti=
on?



=09Borja.


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