You can easily capture the configuration file from any network devices like Cisco Routers, Switches etc.. with Putty. Download Putty
Follow below steps..
1. Launch Putty and connect to your Cisco router/switch/ASA
2. Enter the user exec mode (router> enable)
3. Enter the terminal length 0 command (router# terminal length 0) in order to force the router to return the entire response at once, rather than one screen at a time.
NOTE: If this is an ASA the command is a bit different (ASA#terminal pager 0)
This allows you to capture the configuration without extraneous −−more−− prompts generated when the router responds one screen at a time.
4. Right-click on the menu bar of the putty screen and select “change Settings”
5. Go to Session and click on Logging, select “Log all session output”
6. Click on Browse and choose the location and name of the file (I like to place my config file on my desktop – C:\Documents and Settings\Administrator\Desktop\ASAconfig.txt or SW1config.txt)
7. Click apply
8. Now enter the show run command (router# show running-config), Logout and see the output in config.txt on your desktop (or the location you chose).
That's all there is to it. I highly recommend that each time you make a config change you do a quick backup like this. There's nothing easier to do to come back from a failure than to have a recent config just waiting to be pasted in to get your device back online as quickly as possible.