For this lab, you need to reset your router so that they are accessible. This requires a console cable (blue) and a terminal program (hyperterminal win/minicom lin)
NOTE: If you want to try it, you can check to see if there is a password already set before you kill it (I don't usually bother since it is quicker to just reset it). try cisco1 cisco or cis380 if you like.
NOTE: This lab may not work for anything other than a 2621 router. If you have something else, use the internet to find out the hex for yours.
Connect the console cable to the console port on the router and the serial port on the router.
Run the term program connected to com1 9600 81n
Turn on the router.
When you see it start to boot, hit the break key (sometimes you need ctrl break)
Shortly it should crash to a shell and you will see
rommon 1>
This is the root shell of cisco ios. 12 year old hackers dream of this moment so revel in it.
rommon 1>confreg 0x2142
rommon 2>restart
That's it. You overwrote the block of memory where the enable password is stored in the router so now you own it. When it boots up, cancel the startup configuration.
At the prompt
router>en
router>conf t
router conf> en secret somepassword
router conf>exit