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Hi all, I'm using several RUT240 as OpenVPN clients in bridged network setup (TAP), this is needed for my application.

Every RUT240 has its own DHCP server enabled with different pool segments:

Other router (OpenVPN server): 192.168.223.254, DHCP pool 192.168.223.129-250

RUT240_1 (OpenVPN client) 192.168.223.1, DHCP pool: 192.168.223.10-19

RUT240_2 (OpenVPN client) 192.168.223.2, DHCP pool: 192.168.223.20-29

....

I need that every client, connected to each RUT240, get its IP from the RUT240 where it is connected to. So I have to block DHCP request through OpenVPN tunnel. Unfortunately I cannot prevent DHCP request on OpenVPN server side, due to server router firmware bug.

On other router, this could be done using ebtables eg.:

ebtables -A INPUT --in-interface tap11 --protocol ipv4 --ip-protocol udp --ip-destination-port 67:68 -j DROP
ebtables -A INPUT --in-interface tap11 --protocol ipv4 --ip-protocol udp --ip-source-port 67:68 -j DROP
ebtables -A FORWARD --out-interface tap11 --protocol ipv4 --ip-protocol udp --ip-destination-port 67:68 -j DROP
ebtables -A FORWARD --out-interface tap11 --protocol ipv4 --ip-protocol udp --ip-source-port 67:68 -j DROP

How can I do this in RUT240? Is there a way to do it using the web interface?

Thank you
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I answer myself, I simply add following lines to Network->Firewall->Custom Rules:

ebtables -A INPUT --in-interface tap0 --protocol ipv4 --ip-protocol udp --ip-destination-port 67:68 -j DROP
ebtables -A INPUT --in-interface tap0 --protocol ipv4 --ip-protocol udp --ip-source-port 67:68 -j DROP
ebtables -A FORWARD --out-interface ta0 --protocol ipv4 --ip-protocol udp --ip-destination-port 67:68 -j DROP
ebtables -A FORWARD --out-interface tap0 --protocol ipv4 --ip-protocol udp --ip-source-port 67:68 -j DROP

and everything works as expected: every client takes its IP from the DHCP server of the RUT240 where it is connected. Non more DHCP request over bridged tunnel.

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Hi,

Glad you've answered your own question.

Have a nice day!

EB.