How to reset a lost/unknown admin password on a 3Com 3824 Gigabit Ethernet Switch (p/n 3C17400):
- Connect a null modem serial cable to the front Console port on the switch, and plug the other end of the serial cable into your laptop or desktop computer.
- Run Hyperterminal or PuTTY. Set the COM port values to 19200 Baud, 8 Data Bits, No Parity, 1 Stop Bit, No (None) Flow Control.
- Power up the switch. You should see a bunch of diagnostic information scroll by. Eventually your screen should go blank.
- Press Enter on the keyboard a couple of times and you should get to a Login: prompt.
- Type in recover as the username and the password. You should see a warning about resetting the switch and a countdown from 30 seconds.
- Power off the switch before the 30 seconds countdown. Wait a few seconds and power on the switch.
- You should see a bunch of diagnostic information scroll by again. Eventually you will be given a new prompt to change the admin password. Type in your new password. It becomes effective immediately.