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Cisco 2811 router and opening ports 80 and 443

Posted on 2006-11-03
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Last Modified: 2012-08-13
Hi all
I am running server 2003 domain ent edition wiath AD,DNS,DHCP servers.  I am in the process of installaing sophos appliance WS 1000 for web cache (http traffic filtering) and malware filtereing for my domain.  The applicance has two ports at the back one LAN and one WAN.  Under the configuration of the appliance I have to firewall cisco 2811 to accept port 80 and 443 only from this appliance:
Questions:
-120 permit tcp any host 64.xx.xxx.xxx eq www does this command opens up port 80 on this firewall for this appliance of sophos ?
-120 permit tcp any host 64.xx.xxx.xxx eq 443 opens up 443 on this appliance?
If yes
there are other servers on my domain which have ports:
-120 permit tcp any host 64.xx.xxx.xxx eq www opened should I close it?
-120 permit tcp any host 64.xx.xxx.xxx eq 443 (this is excahnge server) do I have to close it?
Configuration:
Other configuration I am thinking of is to make this router the default gateway of my servers which are default gateway for http traffic of my clients.  So that all http traffic has to pass through this appliance.  Is it a good set up to think off?
Help plz
AM


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Question by:amanzoor
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AM:

You're on the right track. You have to know the correct syntax for creating extended access-lists. You can very easily go to the Cisco website to get that.

It should look something like this:

ip access-list extended PERMIT_SOPHOS
permit <source address> <source mask> <destination address> <destination mask> eq <tcp port number or application keyword>

You get the picture. Remember that there is an implicit "deny all/deny any" at the end of each access list, so make sure you have statements for ALL traffic you want permitted and then the implicit (invisible) "deny all" statement at the end of the access list will block everything else.
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Note: When i say destination or soucre mask, I am talkign about a wildcard mask. And also, after the permit keyword, you can specify the general protocol (IP, TCP, UDP, ICMP, etc).

Go to Cisco's website.

http://www.cisco.com/en/US/products/sw/iosswrel/ps5187/products_command_reference_chapter09186a008017d1d4.html#wp1078593
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by:neoponder
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just make sure you apply it on the right interface in the right direction.

i.e. you want it on the inbound side of the external interface...

ip access-group 120 in
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