Dropping unsollicited connections


I have a cisco 1760 router which has port forwarding for ports 25, 80 and 443 for my web services. So if, let's say, I want to open a connection on port 21 of the router, it should not be allowed. The router sends a "connection refused" packet.

What I want to do, is reproduce the DROP behavior of iptables. If I open a connection on port 21, the router should not respond at all and drop the packet.

How can I achieve that?

interface FastEthernet0/0
ip address x.x.x.89
no ip unreachables
ip nat outside
ip virtual-reassembly
speed auto
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Nayyar HH (CCIE RS)Network ArchitectCommented:
That is part of the TCP/IP mode of operation - If the requested service in unavailable a TCP RESET will be sent to the source in response to the SYN

Try using local-policy routing to send this type of traffic to null0: (drop packet)
alex3948Author Commented:
I did the command:

# ip local policy route-map null0

Still same result
Ernie BeekExpertCommented:
I see you have no access list on your outside interface?

Try adding this:
access-list 100 permit tcp any host x.x.x.89 eq 25
access-list 100 permit tcp any host x.x.x.89 eq 80
access-list 100 permit tcp any host x.x.x.89 eq 443
access-list 100 deny ip any any

interface FastEthernet0/0
ip access-group 100 in

I also took the liberty of hiding your public ip.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
alex3948Author Commented:
Works like a charm, thanks !
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.