Re: mac-filtering is not working (nfcan: addressed to exclusive sender for this address)

[Jim Laurino <nfcan.x.jimlaur@dfgh.net>]

On 2005.03.17 17:55, Manuel Schmitz - Port17@gmx.net wrote:
> Hello,
> 
> I am desperately trying to establish mac-filtering on my debian-router.
> 
> - All default chains are empty, policy set to "ACCEPT".
> - I execute
> 
>   iptables -A FORWARD -m mac --mac-source $MY_MAC -j ACCEPT
> 
>   and then set the FORWARD-Policy to "DROP". Now I expect the chain to
>   drop all packages exept these coming from $MY_MAC. Am I right?
> - It does not work. It drops ALL traffic. So why?

How do you know that *all* packets are dropped?
Why would changing the default policy affect a working rule?
Have you done iptables -L -nvx and examined the counts?

The rule is for one direction only - from $MY_MAC to the world,
there is no provision for traffic to $MY_MAC.

A rule like this would handle most reply traffic:
iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT

For a really good reference on iptables in general, check out
http://iptables-tutorial.frozentux.net/


-- 
Jim Laurino
nfcan.x.jimlaur@dfgh.net
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