Reset Cisco 1720 Router to Factory Defaults
Part of building the Cisco lab is setting up the cheap router I bought on Ebay. I want start the configuration from scratch so we will reset the device to factory defaults without knowing the “enable” password. The link listed below is a good start on what needs to be done. We will get “enable” access and erase the startup-config.
http://www.jedge.com/wordpress/2018/05/cisco-router-password-recovery-console-access/
The easiest way I’ve found to issues a “break key sequence” from Kali and minicom is to simulate the effect described at the bottom of the Cisco support document found here.
The connection details to simulate the break key sequence are as follows:
- 1200 baud
- 8 data bits
- 1 stop bits
- No parity
- None (flow control)
$sudo minicom –s
configuration -> Serial port setup
A -> /dev/ttyUSB0 -> Enter
E -> C -> B -> B -> B -> Enter
F -> Enter
configuration -> Exit -> Enter
+-----------------------------------------------------------------------+
| A - Serial Device : /dev/ttyUSB0 |
| B - Lockfile Location : /var/lock |
| C - Callin Program : |
| D - Callout Program : |
| E - Bps/Par/Bits : 1200 8N1 |
| F - Hardware Flow Control : No |
| G - Software Flow Control : No |
| |
| Change which setting? |
+-----------------------------------------------------------------------+
| Screen and keyboard |
| Save setup as dfl |
| Save setup as.. |
| Exit |
| Exit from Minicom |
+--------------------------+
Modify minicom settings back to the default settings for communicating with a Cisco device as detailed above. While in minicom enter the following commands.
CTRL-A -> SHIFT-Z -> SHIFT-P
E -> C -> X -> Enter
configuration -> Exit -> Enter
+-----------------------------------------------------------------------+
| A - Serial Device : /dev/ttyUSB0 |
| B - Lockfile Location : /var/lock |
| C - Callin Program : |
| D - Callout Program : |
| E - Bps/Par/Bits : 9600 8N1 |
| F - Hardware Flow Control : No |
| G - Software Flow Control : No |
| |
| Change which setting? |
+-----------------------------------------------------------------------+
| Screen and keyboard |
| Save setup as dfl |
| Save setup as.. |
| Exit |
| Exit from Minicom |
+--------------------------+
rommon 1 > confreg 0x2142
You must reset or power cycle for new config to take effect
rommon 2 > resetRouter>enable
Router#write erase
Erasing the nvram filesystem will remove all files! Continue? [confirm]
[OK]
Erase of nvram: complete
Router#config t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#config-register 0x2102
Router(config)#exit
Router#write mem
00:03:01: %SYS-5-CONFIG_I: Configured from console by console
Building configuration...
[OK]
Router#reload
Proceed with reload? [confirm]Click HERE for the complete session log.
