Why is this happening?(cisco)

Barrypr

A cisco router that I have set up at a customer site is not holding a nat setting, this was not an issue until recently, say past few weeks:

"ip nat inside source static tcp <ip address> 25 <ip address> 25 extendable"

I have several nat lines like this, but this is the only one that somehow deletes itself from time to time, in order to re-add the line I must reboot the router then add it, if I enter the command without rebooting it does not save.

We have had a recent issue woth someone trying to gain access to this router via a dictionary attack not sure if that has anything to do with it as of recent there has been no attacks, does anybody have any idea why this is happening to just port 25!

networker050184

Have you checked for any kind of bugs in your version of IOS? Are you issuing a copy run start or simillar after putting in the command? Maybe its not saving and the router reboots and the config is gone. Also check the config register.

Might want to change the password to be on the safe side also.