Using iptables for forward some packets

Bob Edwards Robert.Edwards at
Tue Jul 2 10:32:14 EST 2002

Michael Still wrote:
> Hello.
> I am having iptables confusion issues. I have a packet (a DHCP request in
> this case). The packet arrives on my firewall on wlan0, and I want to push
> it straight out eth0. I then need to push the response back the same
> way...
> I have:
> echo "Forwarding selected wireless packets"
> iptables -A FORWARD -i wlan0 -o eth0 -p udp --dport 67 -j ACCEPT
> iptables -A FORWARD -i eth0 -o wlan0 -p udp --dport 67 -s -j ACCEPT
> And I'm proud to say it doesn't work. Can I have a hint please?
> Mikal

You might want to run dhcrelay (man dhcrelay(8)) on your router as I
don't think that your router is likely to want to forward the DHCP
request packets (which are broadcasts) onto the other subnet.


Bob Edwards.

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