Scenario:
Two RB2011UAS-2HnD routers, followed the wiki at http://wiki.mikrotik.com/wiki/Manual:BCP_bridging_(PPP_tunnel_bridging) to setup the routers for bridging.
Problem found:
(a) After successful connection, from the “/interface bridge port” on both routers, an dynamic port “unknown” is seen, I believe it shall refer to the “PPTP” tunnel.
(b) I would like to block the transverse of DHCP request packets in the PPTP tunnel, thus I add a bridge filter rule on both routers to block the packet, however, from the “/interface bridge filter”, I cannot find neither “unknown” nor any pptp related interface at the “in-interface” or “out-interface” option.
Further finding:
I add a bridge filter rule to log all DHCP packet seen in the bridge, the filter do record the DHCP packet traffic in the PPTP tunnel (logged as the correct interface name, not “unknown”). Thus I believe the bridge filter is able to recognize the traffic explicitly from or to the PPTP tunnel port.
Comment:
As a workaround I need to create an eoip tunnel on top of the PPTP tunnel in order to enable DHCP blocking bridge filter rule. I feel It is a bit stupid to create a GRE tunnel (eoip) inside another GRE tunnel (PPTP) due to such behaviour. I shall be grateful if this problem can be solved by enabling the selection of this dynamic bridge port at the in-interface or out-interface at the bridge filter page.
Any help is highly appreciated. 