ASA5505 Deny IP Spoof Syslog Message

Posted on 2010-04-05
Medium Priority
Last Modified: 2012-05-09

I am getting the following Syslog Message on our Cisco ASA5505 device:

Deny IP spoof from ( to on interface inside

I have not been able to figure out exactly where this is coming from. Any ideas?

Thank you,

Question by:OokLoc
  • 2
LVL 33

Expert Comment

ID: 29857151
Check all your interfaces, see that the subnets and masks are correct.   is there anything on the management interface ?  

Check the ARP table and see if you can get a mac address from that IP.  


Author Comment

ID: 29910344

I checked all the interfaces, subnets, and masks. There is nothing on the management interface. Also, the ARP table does not show an ip address of We are going to run wireshark and see if we can spot whats causing these critical errors. I'll post what I find.

Thank you,


Accepted Solution

OokLoc earned 0 total points
ID: 29926712

We have found the problem. It seems a USB Camera created a new network connection with a description of "Microsoft TV/Video Connection" on one of our machines. This connection had an Autoconfiguration IP Address of  We tried to just right-click and disable it, but the system would not let us because it was using some resource.

So, we opened the TCP/IP properties, then the Advanced TCP/IP settings button, and under the DNS tab we unchecked the box for "Register this connection's addresses in DNS" and rebooted.  The connection was no longer shown. This seems to have solved the issue.

Thank you,


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