We have seen issues when using backups after the sensor has had a new software update applied.
This is because the software update will modify the sensor by adding new configurations or modifying existing signatures. The software update may also modify your current-config to ensure it works with the new version.
HOWEVER, if you then try to go and use a backup from before the update, the sensor may not accept it.
So to be sure to not run into this issue, it is best to always make a fresh backup after the software has been updated. This way you know your sensor will accept your backup-config.
If for some reason your sensor is not accepting the backup config then you can try entering the commands one at a time. The backup config is a listing of the CLI commands, so you just need to open the file and enter the configuration commands one at a time. Eventually you will find which command is causing the issue. It is most likely that the new software update on the sensor has modified that signature.
If you have a major sensor failure and need to recover the sensor then you can follow the procedure below:
1) Recover the sensor back to the main software image. Follow the instructions for your sensor type:
2) Login as cisco with password cisco (change the password to a new password).
3) Run setup to initialize the sensor.
4) Now apply all of the software updates to get the sensor back to the same version it was at the last time you backed up your configuration (the version on the sensor needs to match the sensor version from your backup to ensure all commands are accepted).
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...