Solved

Dropping unsollicited connections

Posted on 2012-04-04
4
403 Views
Last Modified: 2012-04-05
Hi!

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.89 255.255.255.0
no ip unreachables
ip nat outside
ip virtual-reassembly
speed auto
full-duplex
!
0
Comment
Question by:alex3948
  • 2
4 Comments
 
LVL 15

Expert Comment

by:Nayyar HH (CCIE RS)
ID: 37808614
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)
0
 

Author Comment

by:alex3948
ID: 37809021
I did the command:

# ip local policy route-map null0

Still same result
0
 
LVL 35

Accepted Solution

by:
Ernie Beek earned 500 total points
ID: 37810166
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.
0
 

Author Comment

by:alex3948
ID: 37814311
Works like a charm, thanks !
0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

To setup a SonicWALL for policy based routing to be used with the Websense Content Gateway there are several steps that need to be completed. Below is a rough guide for accomplishing this. One thing of note is this guide is intended to assist in the…
In the world of WAN, QoS is a pretty important topic for most, if not all, networks. Some WAN technologies have QoS mechanisms built in, but others, such as some L2 WAN's, don't have QoS control in the provider cloud.
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

810 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question