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Date:      Wed, 6 Oct 1999 12:36:39 -0700 (PDT)
From:      Brooks Davis <>
To:        Bill McMilleon <>
Cc:        freebsd-questions@FreeBSD.ORG
Subject:   Re: Bridging ethernet over serial devices: possible?  How?
Message-ID:  <>
In-Reply-To: <000101bf0f6b$e26f8560$6401a8c0@mchome>

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On Tue, 5 Oct 1999, Bill McMilleon wrote:

> I have two external modems and would like to do a
> LAN to LAN connection that bridges ethernet frames 
> (I need IP and IPX on both ends and it needs to look like 
> one big LAN, read: no NAT).  Can anyone point me in the 
> direction I need to go to get this working under 
> FreeBSD (3.2 or 3.3)?  I've seen a Bridging-HOWTO for 
> Linux that discusses the program BRCFG in applications for
> NIC-to-NIC bridging, but I don't see anything about 
> NIC-to-serial device bridging.

NIC-to-NIC bridging is available in -stable and -current as a kernel
option.  I don't think there is currently any support for NIC-serial-NIC
bridging, but it wouldn't be hard to write.  I wrote a simple NIC-NIC
bridge in a couple of hours using bpf for network reading and writing
(unfortunatly, I can't give you the code because it's my companies and I
specificaly designed it to do evil things to the packets crossing the
bridge to demonstrate security problems in certain protocols.) To do it
over serial, you would just have to write a bit more code that passed
bridged packets and bridge table updates across the serial line.  There
might also be a cool way to do it all with netgraph and some modifications
to the current bridge code, but I don't know enough about either system to

> One other thing: does the linux program brcfg work under 
> FreeBSD's linux emulation?

I don't think so.

-- Brooks

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