Re: MAC SOURCE

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On Mon, Jul 11, 2005 at 07:58:15PM +0500, azeem ahmad wrote:
> hi list
> here is a script that i want to use to block unauthorized MACs on my 
> network. but the problem is that  its not blocking all other MACs that r 
> not specified in the script. plz help me out n telll wots the reaon of this
> ########################################################
> iptables -A INPUT -m mac --mac-source $MAC -j ACCEPT
> iptables -A FORWARD -m mac --mac-source $MAC -j ACCEPT
> iptables -A INPUT -m mac --mac-source ! 11:22:33:44:55:66 -j DROP
> iptables -A FORWARD -m mac --mac-source ! 11:22:33:44:55:66 -j DROP
> iptables -t nat -A POSTROUTING -i eth1 -j MASQUERADE
> ###################################################
> even now it is MASQUERADING all the macs that r not specified in the script.
> waiting for ur response
> Regards

i would do it this way:

  iptables -N check_mac
  iptables -A check_mac -m mac --mac-source $MAC1 -j RETURN
  iptables -A check_mac -m mac --mac-source $MAC2 -j RETURN
  # iptables -A check_mac -j LOG --log-prefix "INVALID MAC: "
  iptables -A check_mac -j DROP

  iptables -A INPUT -j check_mac
  iptables -A FORWARD -j check_mac

and then put your regular filter rules in INPUT and FORWARD after the
jump to check_mac; as only packets with either $MAC1 or $MAC2 will ever
make it out of the check_mac chain.

-j

--
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