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ASA Shunning internal IP

Posted on 2016-10-12
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Last Modified: 2016-10-12
Every once and awhile our email filter gets shunned by our ASA. Doing a no shun 192.168.0.208 fixes it, but I'm not sure why it is being shunned at all since the Threat detection is set to exclude the 192.168.0.0/23 subnet (see image).capture
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Question by:bhieb
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Expert Comment

by:Jan Springer
ID: 41841015
Sometimes mail servers generate a lot of traffic.  Either adjust the threat detection or exclude that IP.

And check that it hasn't been compromised.
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Author Comment

by:bhieb
ID: 41841034
The ip should be excluded per the screenshot, the whole subnet is.
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by:Jan Springer
ID: 41841038
I see the screenshot but it apparently isn't.

Is the exclusion visible in CLI?
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Author Comment

by:bhieb
ID: 41841046
What is the cli command I can check.
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Expert Comment

by:Jan Springer
ID: 41841048
sh run | i shun

You should see:

threat-detection scanning-threat shun except ip-address 192.168.0.0 255.255.254.0
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Author Comment

by:bhieb
ID: 41841049
show shun returns nothing
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Author Comment

by:bhieb
ID: 41841050
threat-detection scanning-threat shun except ip-address 192.168.0.0 255.255.254.0

It appears to be excluded.
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Jan Springer earned 500 total points
ID: 41841057
We must have posted at the same time.

I have never seen an excluded IP get put on a shut list.  Having said that, I don't exclude subnets.

I would recommend adding the mail server IP with a /32 mask to see if that corrects the issue.
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Author Comment

by:bhieb
ID: 41841060
I agree it is really weird, and it has been well over a year since I last touched the firewall and this config has not changed. I think I have smartnet on it, so I can just log a ticket and make them fix it. I'm sure I'm due for an os upgrade as well.

Was just hoping it was something easy.
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Expert Comment

by:Jan Springer
ID: 41841069
It might be that it's a bug when working with a subnet.

Also, there have been several security vulnerabilities -- make sure that you get a release that covers them all and stays within the same train so that you don't have to buy more memory (if you're running something older).
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