Friday, December 9, 2016

Cisco Catalyst L2/ L3 Switch password recovery

  1. Attach a terminal or PC with terminal emulation (for example, Hyper Terminal) to the console port of the switch.
    Use the following terminal settings:
    • Bits per second (baud): 9600
    • Data bits: 8
    • Parity: None
    • Stop bits: 1
    • Flow Control: Xon/Xoff

  2. Unplug the power cable.
  3. Power the switch and bring it to the switch: prompt:
    For 2900XL, 3500XL, 2940, 2950, 2960, 2970, 3550, 3560, and 3750 series switches, do this:
    Hold down the mode button located on the left side of the front panel, while you reconnect the power cable to the switch.
  4. The example below uses Hyperterm to break into switch: mode on a 2955.
    C2955 Boot Loader (C2955-HBOOT-M) Version 12.1(0.0.514), CISCO DEVELOPMENT TEST
    VERSION
    Compiled Fri 13-Dec-02 17:38 by madison
    WS-C2955T-12 starting...
    Base ethernet MAC Address: 00:0b:be:b6:ee:00
    Xmodem file system is available.
    Initializing Flash...
    flashfs[0]: 19 files, 2 directories
    flashfs[0]: 0 orphaned files, 0 orphaned directories
    flashfs[0]: Total bytes: 7741440
    flashfs[0]: Bytes used: 4510720
    flashfs[0]: Bytes available: 3230720
    flashfs[0]: flashfs fsck took 7 seconds.
    ...done initializing flash.
    Boot Sector Filesystem (bs:) installed, fsid: 3
    Parameter Block Filesystem (pb:) installed, fsid: 4
    
    *** The system will autoboot in 15 seconds ***
    Send break character to prevent autobooting.
    
    
    !--- Wait until you see this message before !--- you issue the break sequence. !--- Ctrl+Break is entered using Hyperterm.
    
    
    The system has been interrupted prior to initializing the flash file system to finish 
    loading the operating system software:
    
    flash_init
    load_helper
    boot
    switch:
  5. Issue the flash_init command.
    switch: flash_init
    Initializing Flash...
    flashfs[0]: 143 files, 4 directories
    flashfs[0]: 0 orphaned files, 0 orphaned directories
    flashfs[0]: Total bytes: 3612672
    flashfs[0]: Bytes used: 2729472
    flashfs[0]: Bytes available: 883200
    flashfs[0]: flashfs fsck took 86 seconds
    ....done Initializing Flash.
    Boot Sector Filesystem (bs:) installed, fsid: 3
    Parameter Block Filesystem (pb:) installed, fsid: 4
    switch:
    
    !--- This output is from a 2900XL switch. Output from !--- other switches will vary slightly.
    
    
  6. Issue the load_helper command.
    switch: load_helper
    switch:
  7. Issue the dir flash: command.
    Note: Make sure to type a colon ":" after the dir flash.
    The switch file system is displayed:
    switch: dir flash:
    Directory of flash:/
    2    -rwx  1803357   <date>               c3500xl-c3h2s-mz.120-5.WC7.bin
    
    !--- This is the current version of software.
    
    4    -rwx  1131      <date>               config.text
    
    !--- This is the configuration file.
    
    5    -rwx  109       <date>               info
    6    -rwx  389       <date>               env_vars
    7    drwx  640       <date>               html
    18   -rwx  109       <date>               info.ver
    403968 bytes available (3208704 bytes used)
    switch:
    
    !--- This output is from a 3500XL switch. Output from !--- other switches will vary slightly.
    
    
  8. Type rename flash:config.text flash:config.old to rename the configuration file.
    switch: rename flash:config.text flash:config.old
    switch:
    
    !--- The config.text file contains the password !--- definition.
    
    
  9. Issue the boot command to boot the system.
    switch: boot
    Loading "flash:c3500xl-c3h2s-mz.120-5.WC7.bin"...###############################
    ################################################################################
    ######################################################################
    File "flash:c3500xl-c3h2s-mz.120-5.WC7.bin" uncompressed and installed, entry po
    int: 0x3000
    executing...
    
    !--- Output suppressed. !--- This output is from a 3500XL switch. Output from other switches !--- will vary slightly.
    
    
  10. Enter "n" at the prompt to abort the initial configuration dialog.
    --- System Configuration Dialog ---
    At any point you may enter a question mark '?' for help.
    Use ctrl-c to abort configuration dialog at any prompt.
    Default settings are in square brackets '[]'.
    Continue with configuration dialog? [yes/no]: n 
    
    !--- Type "n" for no.
    
    Press RETURN to get started.
    
    !--- Press Return or Enter.
    
    Switch>
    
    !--- The Switch> prompt is displayed.
    
    
  11. At the switch prompt, type en to enter enable mode.
    Switch>en
    Switch#
  12. Type rename flash:config.old flash:config.text to rename the configuration file with its original name.
    Switch#rename flash:config.old flash:config.text
    Destination filename [config.text] 
    
    !--- Press Return or Enter.
    
    Switch#
  13. Copy the configuration file into memory.
    Switch#copy flash:config.text system:running-config
    Destination filename [running-config]? 
    
    !--- Press Return or Enter.
    
    1131 bytes copied in 0.760 secs
    Sw1#
    The configuration file is now reloaded.
  14. Overwrite the current passwords that you do not know. Choose a strong password with at least one capital letter, one number, and one special character.
    Note: Overwrite the passwords which are necessary. You need not overwrite all of the mentioned passwords.
    Sw1# conf t
    
    
    !--- To overwrite existing secret password
    
    Sw1(config)#enable secret <new_secret_password>
    
    
    
    !--- To overwrite existing enable password
    
    Sw1(config)#enable password <new_enable_password>
    
    
    
    !--- To overwrite existing vty password
    
    Sw1(config)#line vty 0 15
    Sw1(config-line)#password <new_vty_password>
    
    Sw1(config-line)#login
    
    
    !--- To overwrite existing console password
    
    Sw1(config-line)#line con 0
    Sw1(config-line)#password <new_console_password>
    
    
  15. Write the running configuration to the configuration file with the write memory command.
    Sw1#write memory
    Building configuration...
    [OK]
    Sw1#