Hi Everyone, I need help urgently. I have setup a mikrotik RouterOS on a Compaq P4 with 1Gb Ram. We assign Public address to every client and we have a /25 network.

Static ARP is used to tie IP to MAC address, but when an IP address is changed on a client's network, he is still able to pass traffic. I was informed it is bcosI have ether1 and ether2 bridged.

Can someone please tell me how best to setup this network to achieve my objective?

Maybe, define address list in /ip fir add
then make 2 (two) rules for your "Transparent Bridging" as follows:

chain=forward connection-state=related action=accept
chain=forward connection-state=established action=accept
chain=forward connection-state=new src-address-list=... action=accept
chain=forward protocol=tcp action=reject reject-with=tcp-reset
chain=forward protocol=udp action=reject reject-with=icmp-net-prohibited

Hi Friend,
Thanks a million. I will try out and get back whatever happens.

Austin