Strange GRE reverce path check error

Bernard Magny · ‎02-02-2009

Hello,

On one of my inside interface I constantly get this error:

Deny GRE reverse path check from 90.53.3.2 to 90.53.3.1 on interface Operations

I'm having difficulties finding out where it comes from.

we don't have any IPs in that range on the inside of the network. It must be some kind of server with a bad configuration. I can't find the source IP in the ARP table of the switch.

I was wondering if someone can guide me in the right direction to find out what device is doing this.

Thanks

passioncas · ‎02-02-2009

hi..

Please let me know the GRE interface IP address.Assume that the GRE Tunnel has been configured over internet.Then it can be an IP address configured on the GRE interface

Please let me know

Bernard Magny · ‎02-02-2009

I have no GRE tunnel configured.

The outside ip is 83.244.220.82

passioncas · ‎02-02-2009

Hi

Hope you are getting this error on the Switch.request you to share the configuration of the Switch

Regards

Bernard Magny · ‎02-02-2009

I don't understand? this is on a ASA device.

passioncas · ‎02-02-2009

Okay.

This is a spoofed attack and are getting blocked as Reverse path Checking has been enabled on ASA.Nothing to do with this as this is getting blocked by the ASA.Any query please refer the below link

http://www.cisco.com/en/US/docs/security/asa/asa72/system/message/logmsgs.html#wp1279897 and check the error number 106021

hope to help

Bernard Magny · ‎02-02-2009

I understand this, but it's on the inside of my network. So I would like to find a way to find what host is doing this.

Thanks