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Cisco ASA5510 - LAND ATTACK

Posted on 2013-05-14
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Last Modified: 2013-05-20
I want to know if there is anything else I should be doing to mitigate against a Denial of Service Attack that I am currently experiencing.  I have a customer whose network was very slow.  I got into the ASA5510 and saw it was being hammered.  Over 50,000 connections to some of my static NAT's.  I was losing 2 out of every 4 pings to the ASA because it was so overloaded.  I set a per connection client limit on the addresses being targeting on my network, which seems to have  mitigated the problem, but now I'm constantly seeing messages that that per-client connection has been exceeded, as well as a message stating "Deny IP due to Land Attack from x.x.x.136 to x.x.x.136."  Source and destination are the same.  I called my ISP, but I got an email stating that it may take them awhile to investigate due to the amount of abuse emails they receive.  Is there anything else I can do to stop the attack?
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Question by:denver218
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rharland2009 earned 167 total points
ID: 39166376
https://supportforums.cisco.com/docs/DOC-14318

This is a decent rundown of why you may be seeing these.
Is the IP address mentioned in the Land Attack one of yours, or one you're not familiar with?
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by:denver218
ID: 39166395
It's one of my Addresses in my public IP block
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by:naderz
naderz earned 167 total points
ID: 39167047
Do you have IPS enabled? If so, try disabling that and test. You may be experiencing false positives.
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by:asavener
asavener earned 166 total points
ID: 39169741
If you access any of your internal/published resources via their public IP addresses, then the LAND attack notifications are likely due to that.
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by:denver218
ID: 39182291
Thanks for all your comments.  It was DoS attack, the ASA was doing its job blocking all the traffic, but I had to report it to the ISP so they could put an ACL on their side to stop the traffic.  It was coming in at such high rates, that I had to get the ISP involved.  The ISP saw it right away and was able to take care of it.  Thanks.
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by:denver218
ID: 39182295
Thanks.
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