How to block the SMTP port 25 on Cisco router

[mukeshrulaniya]

Hello All,

                We are running ISP and now a days we have many spam in our network, we want block the SMTP port 25 block on Cisco router 7200.

                We have not any smtp server. we want block the port 25 at our core router. So we can block the spam in our network .Please advise me for this its urjent issue.

Thanks

Mukesh

[rsimoni · Accepted solution]

with an acl blocking it

access-list xxx deny tcp any any eq smtp

[mukeshrulaniya]

Hello Riccardo,

I don't want to block it totally, i need a dynamic rule that will block it from like 12 hours when it detect spam activity.

thanks

[rsimoni]

I am not aware of anything like that available for routers. I don't see any quick and easy procedure to achieve that (thinking of complicated eem scripts checking traffic... but I guess it is kind of impossible to have the exact goal)  You might want to move this rule to a fw where you can have far greater flexibility in that sense  or...  you remove the rule after the attack is over.  Riccardo