Access Lists question

[Safar Safarov]

Hello,

I have the following ACL:

ip access-list extended TEST

permit tcp 192.168.1.0 0.0.0.255 any eq www

Would it permit only HTTP or any service via 80 port (like skype, youtube streaming, etc.)?

Thanks.

[Giuseppe Larosa]

Hello Safar,

the access-list tests the OSI layer4 information on traffic packets.

if the protocol is TCP and the destination port is 80 the traffic is permitted, No tests is performed at application level so if the application is HTTP or is another one using TCP 80 is not checked by the ACL. So forms of tunneling over TCP 80 are permitted as they appear as regular TCP port 80 at OSI layer 4.

Hope to help

Giuseppe

[Safar Safarov]

Hello Giuseppe,

many thanks for your reply. Any way to accomplish this task (to inspect the application) to allow only web browsing? I'm using 2921 ISR.

Thanks,

Safar.

[Jeff Van Houten · Accepted solution]

You can look at nbar and inspect statements, but it sounds like you may need to look at an outbound application firewall.

Sent from Cisco Technical Support iPad App

[Joseph W. Doherty · Accepted solution]

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Posting

As Jeff has already noted, NBAR might be a simple option.

[Safar Safarov]

Thanks a lot!