Here is the original link from cisco

Use a TFTP Server to Backup and Restore a Configuration

Before you proceed with this method, make sure you have a TFTP server on the network to which you have IP connectivity.

1. At the Router> prompt, issue the enable command, and provide the required password when prompted.

   The prompt changes to Router#, which indicates that the router is now in privileged mode.

2. Copy the running configuration file to the TFTP server:
   

   CE_2#copy running-config tftp:
   Address or name of remote host []? 64.104.207.171
   Destination filename [ce_2-confg]? backup_cfg_for_my_router
   !!
   1030 bytes copied in 2.489 secs (395 bytes/sec)
   CE_2#

3. Open the configuration file with a text editor. Search for and remove any line that starts with “AAA”.

   Note: This step is to remove any security commands that can lock you out of the router.

4. Copy the configuration file from the TFTP server to a new router in privileged (enable) mode which has a basic configuration.
   

   Router#copy tftp: running-config
   Address or name of remote host []? 64.104.207.171
   Source filename []? backup_cfg_for_my_router
   Destination filename [running-config]?
   Accessing tftp://10.66.64.10/backup_cfg_for_my_router...
   Loading backup_cfg_for_router from 64.104.207.171 (via FastEthernet0/0): !
   [OK - 1030 bytes]
   
   1030 bytes copied in 9.612 secs (107 bytes/sec)
   CE_2#