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configuring cisco router to block all traffic except port 443 and 25 to my on-to-one NAT public IP address

Posted on 2007-10-19
Medium Priority
Last Modified: 2008-01-09
Cisco Router RV016
I am using a cisco router firewall for my network.  I recently set up exchange server and used the one-to-one NAT feature on the router to forward all incoming traffic from a public IP to the internal address of my server.  That worked fine.  However, now I am trying to secure my mail server up from incoming attacks on that public IP.  Is there a way to block all incoming traffic on that public IP except for port 25 and 443?

Question by:kzackery
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Expert Comment

ID: 20108552
I'd use access lists. If you use an access list, it will deny all the traffic except what you specify in the list. Furthermore, you can specify what port numbers you want to allow. Cisco has a good article on access lists here:

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Accepted Solution

Don Johnston earned 500 total points
ID: 20108744
What you've really got is a Linksys router. Cisco bought Linksys a while back but they maintained their existing product line.

Look under the firewall tab. You should see an area where you can create "rules" that determine which traffic is allowed in.

Author Comment

ID: 20109072
Ok don,
I got it.  Correct me if I'm wrong but it should be set to local are network and then the source ip would be the public ip address that I want to block traffic comming from and the destination would be that of my mail server.  How do I know that the ports are being blocked now that I have set it.  Is there a way to verify?
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Expert Comment

by:Don Johnston
ID: 20109218
Sorry. I can't remember the screen and the doc's don't have very good screen shots. As I recall, it was pretty straightforward. I think you can specify that traffic from any address can come in only if it's going to a specific port.

Author Comment

ID: 20109303
Is there a way to check to see if the ports are blocked?
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Expert Comment

by:Don Johnston
ID: 20109344
It should show in the firewall or filter settings

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