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ASR9000/XR: How to reset a lost password (password recovery on IOS-XR)

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Introduction

This document shows you how to reset a lost password or when you have locked yourself out due to a problematic AAA configuration.

 

Core Issue

Because IOS-XR is substantially different in the way config files are managed, the standard trick of conf-reg 0x2142 will not work for IOS-XR.

You can lock yourself out if you are configuring aaa authentication to tacacs with no local fall back, if the tacacs server is unavailable there

is no way for you to get in.

 

eg:

aaa authentication login default groupt tacacs

 

Also this procedure is good when you have forgotten the password to your super user in IOS-XR to manage your machine.

 

Resolution

 

The following step through guide can be tried, the details of each step are listed below with more explanation:

 

  • •1)       Fixing AAA configuration errors  
    • •a.       On the standby RP/RSP from the CONSOLE port hit the ESC key and type ‘ksh’ without quotes and hit ENTER  
      • i.      Login with a local username and password
      • ii.      If this fails get the standby RP/RSP into ROMMON
      • iii.      Bypass KSH authentication with AUX_AUTHEN_LEVEL=0 and boot
      • iv.      Try step 1a again or use the AUX port and go to step 1b
    • •b.       View and edit the configuration from KSH  
      • i.      Save the configuration to harddisk with ‘nvgen -c -l 1 -t 1 -o 1  > harddisk:/backupconfig.txt’
      • ii.      Edit out the bad AAA statements with ‘nano –e /harddisk:/backupconfig.txt’
    • •c.        Try to roll back the configuration with ‘config_rollback –n 0x1’
    • •d.       Bypass AAA and enter exec mode with ‘/pkg/bin/exec –a’
    • •e.        Attempt to use show commands or change the configuration 
      • i.      If this fails reload all RP/RSP ROMMON
      • ii.      On the standby card set IOX_CONFIG_FILE=/harddisk:/backupconfig.txt or use ‘boot <image> -a <bogus_config>’ and boot
      • iii.      Also follows step 2g if you saw issues in 1a
      • iv.      If nothing above worked then this is the only option
  • •2)       Fixing a lost local username/password  
    • •a.       Get the standby RP/RSP into ROMMON  
      • i.      Bypass KSH authentication with AUX_AUTHEN_LEVEL=0 and boot
    • •b.       View the admin configuration with ‘nvgen –b /admin/cfg’
    • •c.        Save the admin configuration to the harddisk and edit out any and all users if you need other portions of this file
    • •d.       Bypass AAA and enter exec mode with ‘/pkg/bin/exec –a’
    • •e.        Attempt to use show commands or change the configuration
    • •f.        If this fails reload all RP/RSP to ROMMON
    • •g.        Set confreg 0x142 or IOX_ADMIN_CONFIG_FILE=/harddisk:/backupconfig.txt on the standby card or ‘boot <image> -o <bogus_config>’ and boot  
      • i.      Note that this does not ignore the exec configuration and will not help if the issue is AAA related
    • •h.       Enter a new username and password when prompted
  • •3)       Fixing both issues 
    • •a.       If you do not know a local login or cannot use the KSH method to recover the configuration then both the IOX_CONFIG_FILE and IOX_ADMIN_CONFIG_FILE will need to be pointed towards non-existent files. Both the admin and exec configurations will be cleared by this method
  • •4)       Make sure to remove any ROMMON variables which were change
  • 5)  XR-VM Username/Password reset procesdure using Sysadmin VM

 

There are 2 steps to this process.

1) Override the BASE running configuration

     When you configure the problematic AAA statement sample as above.

2) Override the admin configuration that stores local usernames and passwords

     When you don't remember any of the local usernames/passwords you have defined locally.

Overriding the Base configuration in XR:

 

Step 1

In rommon set the following variable:

 

rommon> IOX_CONFIG_FILE=/harddisk:/no-config

 

the file no-config is just a non existent file, you can give any name here really.

 

Note: This ROMMON variable will persist and needs to be removed after password recovery. Check the 'clean up' section.

 

 

Step 2

And issue 'sync', this will make the change persistent in the rommon config vars.

 

rommon> sync

 

Step 3

Issue 'i' or 'reset' and when the rsp is booting up, it should ignore  the config file, since there's no config file found on /harddisk:  called no-config

 

rommon> reset

or

rommon> i

 

 

Overriding the ADMIN configuration in XR:

In Admin configuration we store all the local usernames and passwords.

Step 1

 

Similarly you can do the same thing for admin config:

 

IOX_ADMIN_CONFIG_FILE=/disk0:/none

 

You should get prompted for root user/pass and will have a blank config on the box.

You need to load your config and do your modification.

 

Note: This ROMMON variable will persist and needs to be removed after password recovery. Check the 'clean up' section.

Step 2 and 3

are the same as for the base xr config file.

 

Second Option

 

Another way of recoveryof the password is to enable the following again in rommon:

 

rommon> AUX_AUTHEN_LEVEL=0

 

Which will allow the aux port to drop to ksh upon the RSP bootup with no prompt for login.

 

At the prompt you can either type:

 

/pkg/bin/exec -a

 

Which will give you a router prompt: Or simply

 

# Config

 

Which drops you into EXEC config mode.

Example

# uname -a

QNX node0_RSP0_CPU0 6.4.0 2009/12/10-13:43:22PST asr9k ppcbe

# config

RP/0/RSP0/CPU0:RO-A(config)#exit

#

# /pkg/bin/exec -a

RP/0/RSP0/CPU0:RO-A#

RP/0/RSP0/CPU0:RO-A#

RP/0/RSP0/CPU0:RO-A#exit

#

Clean up

Make sure that after you're done with your changes, in case you made the rommon vars persistent, you may want to unset

the variables to get back to the normal files that are used.

 

rommon> unset IOX_ADMIN_CONFIG_FILE

rommon> unset IOX_CONFIG_FILE

rommon> sync

 

All set!

 

If you forget the cleanup, you might see these lines:

 

RP/0/RSP1/CPU0:Oct 28 07:18:37.141 : locald_DSC[301]: %SECURITY-LOCALD-3-LWA_ADD_FAIL : Failed to add the username admin to lightweight authentication password database: No such file or directory

 

Another way to clear the variable:

more nvram:/classic-rommon-var  location 0/RSP1/CPU0

run iox_on 0/RSP1/CPU0 nvram_rommonvar IOX_CONFIG_FILE ""

Step 5


XR-VM Username/Password reset procedure using Sysadmin VM

 

Note: This is not a process to hack router but user need sysadmin username / password for the accessibility of box by bypass XR credentials.

Steps to perform this activity:

1. login to router : I was having console access to the box.

bgl-xdm-009:112> telnet 10.67.30.20 2037
Trying 10.67.30.20...
Connected to 10.67.30.20.
Escape character is '^]'.


User Access Verification

Password:
Password OK

2. Pass interrupts "ctrl + o" to toggle to sysadmin

sysadmin-vm:0_RP0#
*** IDLE TIMEOUT ***

System Admin Username:

3. enter sysadmin username and password

System Admin Username: xxxxx

Password:

xxxxx connected from 127.0.0.1 using console on sysadmin-vm:0_RP0
sysadmin-vm:0_RP0#


4. with this login you can access "sysadmin- VM prompt"

sysadmin-vm:0_RP0#

5. From Sysadmin VM to access XR - VM perform following action

i. list sdr ips
sysadmin-vm:0_RP0# show sdr
Tue Apr 3 05:12:47.110 UTC

SDR: default-sdr
Location IP Address Status Boot Count Time Started
-----------------------------------------------------------------------------
0/RP0/VM1 192.0.0.4 RUNNING 1 03/01/2019 02:10:28
0/RP0/VM2 192.0.0.6 RUNNING 1 03/01/2019 02:10:56

ii. ssh SDR VM1 address

[sysadmin-vm:0_RP0:~]$ssh 192.0.0.4

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
<>
Last login: Fri Mar 1 02:14:39 2019 from 192.0.0.4

iii. Now you are at XR-VM and to disable credential pass "ctrl + a" interrupt

[xr-vm_node0_RP0_CPU0:~]$exec -a

6. After disabling credential you can access XR-VM

RP/0/RP0/CPU0:customer2#

at this stage you can create/ delete / modify user credentials to access router at XR-VM directly.

P/0/RP0/CPU0:customer2#show running-config
Tue Apr 3 05:13:02.445 UTC
Building configuration...
!! IOS XR Configuration version = 6.3.3
!! Last configuration change at Sun Feb 17 23:31:51 2019 by ZTP
!
hostname customer2 >>>
username asd
group root-lr
group cisco-support
secret 5 $1$rdaY$qJt7aNcc8uFKqhP/rK11V1
!

Related Information

It has been seen that sometimes a system autonomously enters password recovery mode. This is identified with:

“enter root-system username”

 

This is due to a ddts known as CSCth03923

You end up providing what you think is a known username and password combination and it failes to get you in.

The solution is simple, just enter a fake username/password that you know for sure has not been configured yet and you're in!

 

 

 

Xander Thuijs - CCIE #6775

Sr Tech Lead ASR9000

Comments
Cisco Employee

hi mirko!

the config in XR is not in a (text) file format like it was in IOS. In XR there is a sysdb (system database) that holds all configuration(s) and parameters and operational data that is queried by components on show commands and configs.

the step 2 to set the no-config is effectively pointing the system to a new database (sort of speak).

this means that the config will be empty on load, upon which you can load a new config, commit it and next time it reboots it will leverage that new config.

a rollback would only be to the previous empty config, so you will lose your commit history.

"sync" is a directive in rommon to save the rommon variables. this gets put in a flat file on the nvram (classic-rommon-variables is the filename).

I would recommend to boot the system with the no-config directive, but not sync (save it). this way when the system boots empty and on the first commit, we basically push it to the database and on next reload the config from the database will be loaded, which is what you saved without losing too much history.

cheers!

xander

Beginner

hi xander, very tnx for your kind reply as usual. so to resume:

1) reboot asr and via console CTRL-C to access ROMMON
2) in ROMMON: IOX_CONFIG_FILE=/harddisk:/no-config
3) in ROMMON: reset (this will reboot asr)
4) the asr will boot with the admin config untouched but without base config
5) login with a root user (i suppose the system with an empty base config fallback automatically to local users, thus checking users in the admin config)
6) rollback configuration last 1/2... and commit

mirko

Beginner

Hi Xander, do you have the process for XRv password recovery? Thank you in advance.

 

Beginner

Hi Xander,

 

I'm trying to reset my local username/pwd on my lab ASR9901, but the options (2 & 3) doesn't seem to work.

When I reset after change, it boots as normal, ignoring nothing. Also I have to give the option -s (soft) -h (hard) for the reset command. Is there a different procedure for ASR9901?

 

Booting IOS-XR 64 bit Boot previously installed image - Press Ctrl-c to stop
S
Please select the operating system and the boot device:
1) Boot to ROMMON
2) IOS-XR 64 bit Boot previously installed image
3) IOS-XR 64 bit Mgmt Network boot using DHCP server
4) IOS-XR 64 bit Mgmt Network boot using local settings (iPXE)
(Press 'p' for more option)
Selection [1/2/3/4]: 1

rommon 1 > unset IOX_CONFIG_FILE
rommon 2 > IOX_ADMIN_CONFIG_FILE=/disk0:/none
rommon 3 > sync
rommon 4 > reset
rommon 5 > reset -h

Resetting hard .......
˜!ý ΝaÿBooting Main Processor
Transferring Console

˜žùŒŒŒŒŒ)”ŒŒ
á
CPU reset reason = 13 (CPU_RESET_AUTO_RESET)
Missing Parameter SERVER_URL

##########################################################
System Bootstrap, Version 22.24 [ASR9K x86 ROMMON],
Copyright (c) 1994-2019 by Cisco Systems, Inc.
Compiled on Tue 07/16/2019 15:41:43.70

BOARD_TYPE : 0x101014
Rommon : 22.24 (Primary)
Board Revision : 5
PCH EEPROM : 0.0
IPU FPGA(PL) : 0.20.1 (Primary)
IPU INIT(HW_FPD) : 2.5.1
IPU FSBL(BOOT.BIN) : 1.104.0
IPU LINUX(IMAGE.FPD) : 1.104.0
DRAX FPGA : 0.35.1
CBC0 : Part 1=54.10, Part 2=54.10, Act Part=2
Product Number : ASR-9901-RP
Chassis : ASR-9901
Chassis Serial Number : FOC2346NBP2
Slot Number : 0
Pxe Mac Address LAN 0 : 6c:31:0e:26:d5:b0
Pxe Mac Address LAN 1 : 6c:31:0e:26:d5:b1
==========================================================
Got EMT Mode as IOS-XR Boot
Got Boot Mode as Disk Boot

Booting to ROMMON - Press Ctrl-c to stop
Y
Please select the operating system and the boot device:
1) Boot to ROMMON
2) IOS-XR 64 bit Boot previously installed image
3) IOS-XR 64 bit Mgmt Network boot using DHCP server
4) IOS-XR 64 bit Mgmt Network boot using local settings (iPXE)
(Press 'p' for more option)
Selection [1/2/3/4]: 2
Selected IOS-XR 64 bit Boot previously installed image, Continue ? Y/N: y

 

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