cisco: factory reset for ASA 5510

Tagged as cisco, networking, ASA, factory reset, rs232, serial

Written on 2015-09-20 19:30:59

For factory resetting an 'Adaptive Security Appliance', some CLI work has to be done. In the following no prior configuration knowledge is assumed.

get a serial connection

Cisco switches are shipped with a blue female DB9-to-RJ45 adapter cable. (A null modem will not help here, as you need a RJ45 plug at the end which you connect to the ASA's CONSOLE port.)

Such a cable has to be connected to your ASA, and either your serial port of your comp. Since most desktops/laptops do not ship with an rs232 interface anymore, get yourself an male-male USB-to-DB9 adapter.

If you do not have the original cisco cable, use a comparable one: Juniper i.e. ships regular RJ45 ethernet cables plus an female-female RJ45-to-DB9 adapter which works just the same.

In the following a linux operating system is assumed; on windows this works, too. However you have to plug in the adapter, and find out which COM port is used via the device manager, you need this information later when using PuTTy.

On linux you can either go along with minicom, or just use screen. (I have the slight feeling I have written down all this somewhere else already on the blog...)

#as root
screen /dev/ttyUSB0 9600

... and you are connected. Cisco devices in general use 9600 baud, 8bit, 1 stop bit, no flow control. Once I read on official docs about 2 stop bits, but it worked with 1, so go figure it out from the manual if you have trouble with these settings.

step by step

  1. power cycle - turn it off and on again, so it freshly boots after you have connected the serial cable

  2. press ESC here during boot:

    Evaluating BIOS Options ... Launch BIOS Extension to setup ROMMON

    Cisco Systems ROMMON Version (1.0(10)0) #0: Fri Mar 25 23:02:10 PST 2005

    Platform ASA5510

    Use BREAK or ESC to interrupt boot. Use SPACE to begin boot immediately.

  3. confirm current configuration register, if promted if you wish to change anything, answer with 'no':

    rommon #0> confreg

    Current Configuration Register: 0x00000001 Configuration Summary: boot default image from Flash

    Do you wish to change this configuration? y/n [n]: n

    rommon #1>

  4. enter: confreg 0x41

  5. enter: boot

  6. after the appliance has rebooted, you should see this prompt: ciscoasa>

  7. enter privileged mode: enable

  8. erase startup config: write erase

  9. enter config mode: configure terminal

  10. config-register 0x01

  11. exit config mode: exit

  12. confirm via show version, see the end: Configuration register is 0x41 (will be 0x1 at next reload)

  13. save: write

  14. reboot: reload

Done. You now have a fresh ASA at your disposal.

Unless otherwise credited all material Creative Commons License by sjas