On Wed, Apr 27, 2005 at 10:15:25AM -0700, Gregory K. Ruiz-Ade wrote:
>On Wednesday 27 April 2005 09:39 am, George Georgalis wrote:
>> Anybody use knockd through a bridge.... On a bridge?
>> I don't think it will work...
>
>Of course it would, if you use a firewalling bridge.  I'm not sure it's 
>supported by default in Linux kernels, but you can use Linux to bridge and 
>still inspect every packet with iptables.  Think of it as just like a 
>firewall, but the "protected" side is the same network segment as the 
>"hostile" side.

I'm dealing with a fairly complex network and I can't disclose it all
anyway, so bear with me.

testing knockd on a box worked fine. when I put it in production, I
couldn't knock through the fairly strict bridge. the bridge does ALLOW
the ports in the combination to pass through, but I cannot knock across
it, and I get no drop/reject entries in the log (target or bridge) either.

With no drop/reject messages, I'm thinking knock is not transmitting
enough of a tcp connection for the bridge think it needs to forward it.
ie a telnet attempt (or some other client that sends more than knock) to
each of the combination ports would hit the trigger.

So I was thinking to fudge it an make the target available and run
knockd on the bridge, to add/remove a FORWARD rule there for access to
the target. Then I recalled, when I tried knockd on lo, I got an error
no MAC address. So I assume it cannot listen on br0 either.

// George



-- 
George Georgalis, systems architect, administrator Linux BSD IXOYE
http://galis.org/george/ cell:646-331-2027 mailto:[EMAIL PROTECTED]

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