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Date:      Thu, 3 Feb 2000 09:56:51 -0500 (EST)
From:      Jim Flowers <jflowers@ezo.net>
To:        Matthew Hagerty <matthew@venux.net>
Cc:        freebsd-isp@FreeBSD.ORG
Subject:   Re: IPFW with NATd
Message-ID:  <Pine.BSI.3.91.1000203093006.7573A-100000@lily.ezo.net>
In-Reply-To: <4.2.2.20000203080148.00abd8a0@mail.venux.net>

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Insights for NATD.

1.  You can have multiple rules each matching a different criteria.  It's 
    just a divert hook to the natd process.

2.  You can set up criteria to bypass natd by placing rules that 
    terminate the ipfw pass ahead of the divert rule.  for example:

    10 allow ip from any to any.that.you.dont.want.to.divert via in.ifc in

3.  ipfw only makes one pass if net.inet.ip.fw.one_pass is set in sysctl

4.  You can run multiple natd with different interfaces such as:

    100 divert 8668 ip from any to any via wi0
    101	divert 8669 ip from any to any via ed0

    You also need multiple natd processes, one at -p 8668 and one at -p 
    8669.  Each can have its own set of rules (-redirect_port, etc.).
    This is useful for having external addresses (via a skip nomad
    connection, for example) act as part of the local network for
    purposes of wandering around a VPN.

5.  Natd processes should be started AFTER any process that modifies the
    interface MTU or there will be difficulties.

6.  Use natd -v to see what is really happening.


Jim Flowers <jflowers@ezo.net>
#4 ISP on C|NET, #1 in Ohio

On Thu, 3 Feb 2000, Matthew Hagerty wrote:
> This (I was hoping) would allow me to make rules based on certain internal 
> hosts, i.e. my internal DNS host needs to talk to my external fake DNS on 
> the bastion host, but no other internal host should be allowed to query the 
> external DNS (bastion) host directly, unless a rule is written specifically 
> for it.
> 
> I did actually get this to work with the DNS example, my fake DNS on the 
> external network could communicate with the internal DNS and 
> vice-versa.  But when I tried to add a rule to allow the rest of the 
> internal hosts to surf, etc. it broke.  The only error I got was a "can't 
> send packet back" error on the terminal.
> 
> Any insight on this would be greatly appreciated.
> 
> Thanks,
> Matthew Hagerty 


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