Access Lists question

Answered Question
Aug 19th, 2012

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.

I have this problem too.
0 votes
Correct Answer by JosephDoherty about 1 year 8 months ago

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The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

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In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

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

Correct Answer by jpvh12345 about 1 year 8 months ago

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

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Giuseppe Larosa Sun, 08/19/2012 - 07:37

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 Sun, 08/19/2012 - 10:39

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.

Correct Answer
jpvh12345 Sun, 08/19/2012 - 15:22

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

Correct Answer
JosephDoherty Sun, 08/19/2012 - 18:09

Disclaimer


The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

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

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Posted August 19, 2012 at 4:17 AM
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