Description

  • This article addresses the problem of an EX4300 device continuously displaying the user prompt without providing the expected password prompt. 
  • Users attempting to log in, even with the "root" username, are stuck in a loop without being prompted to enter their password. 
  • This issue affects both console and SSH access methods

Symptoms

  • EX4300 device continuously displays the user prompt without providing the expected password prompt
jtac-ex4300-48t-r2035 (ttyu0)

login: root

jtac-ex4300-48t-r2035 (ttyu0)

login: root

jtac-ex4300-48t-r2035 (ttyu0)

login: root

jtac-ex4300-48t-r2035 (ttyu0)
  • This issue occurs when an EX4300 device boots with Junos OS 14.1 code and has unsupported configuration statements from a newer Junos OS version, such as 21.4. 
  • Here's an example scenario:
    • The EX4300 device has Junos OS 21.4 installed on the primary partition and Junos OS 14.1 on the backup partition.
root@jtac-ex4300-48t-r2035> show system snapshot media internal 
fpc0:
--------------------------------------------------------------------------
Information for snapshot on       internal (/dev/da0s1a) (primary)
Creation date: Aug 30 15:54:20 2023
JUNOS version on snapshot:
  jcrypto-ex: 21.4R3-S3.1
  jdocs-ex: 21.4R3-S3.1
  jphone-home: 21.4R3-S3.1
  jsd    : powerpc-21.4R3-S3.1-jet-1
  jsdn-powerpc: 21.4R3-S3.1
  junos  : ex-21.4R3-S3.1
  junos-ex-4300: 21.4R3-S3.1
  jweb-ex: 21.4R3-S3.1
Information for snapshot on       internal (/dev/da0s2a) (backup)
Creation date: Aug 30 15:22:51 2023
JUNOS version on snapshot:
  jdocs-ex: 14.1X53-D12.17
  junos  : ex-14.1X53-D12.17
  junos-ex-4300: 14.1X53-D12.17
  jweb-ex: 14.1X53-D12.17
  • A user configures a feature (e.g., "eracl-ip6-match srcip6-and-destip6") in Junos OS 21.4 that is not supported in Junos OS 14.1.
{master:0}[edit]
labroot@jtac-ex4300-48t-r2035# set system packet-forwarding-options eracl-ip6-match srcip6-and-destip6 

labroot@jtac-ex4300-48t-r2035# commit and-quit 
[edit system packet-forwarding-options]
  'eracl-ip6-match'
    warning: Restart PFE for the eracl-ip6-match option to take effect
configuration check succeeds
commit complete
Exiting configuration mode
  • The device is rebooted, either automatically or manually forced to boot from the alternate partition with Junos OS 14.1.
root@jtac-ex4300-48t-r2035> request system reboot media internal slice alternate 
Reboot the system ? [yes,no] (no) yes 

Shutdown at Wed Sep  6 13:09:37 2023.
[pid 16663]

                                                                               
*** System shutdown message from root@jtac-ex4300-48t-r2035 ***              

System going down in 1 minute                                                  
  • During boot-up, the device reports unsupported configuration errors, indicating the presence of configurations not compatible with the 14.1 code.

Creating initial configuration...mgd: error: schema: dbs_remap_daemon_index: could not find daemon name 'fcd'
/config/juniper.conf:72:(29) syntax error at 'packet-forwarding-options'
  [edit system]
    'packet-forwarding-options {'
      syntax error
/config/juniper.conf:76:(5) error recovery ignores input until this point at '}'
  [edit system]
    '}'
      error recovery ignores input until this point
[edit]
  'system'
    warning: statement has no contents; ignored
mgd: Running FIPS Self-tests
 
  • The device continuously displays the user prompt post boot-up

Solution

To recover from an unsupported configuration on the EX4300, follow these steps:
  • If the device boots up with Junos OS 14.1 on both partitions, perform a USB Format installation with the latest code. This ensures you have the correct software version.
  • If the device has the latest image on one partition and an older version on the other, use the following procedure to force the device to boot from the partition with the latest code:
    • Power cycle the box.
    • During boot-up, watch for the following prompt:
/kernel data=0xb5cbe6+0xd582a syms=[0x4+0x9d690+0x4+0xe62e2]


Hit [Enter] to boot immediately, or space bar for command prompt.
  • When you see the prompt, press the space bar to break the boot sequence.
  • At the Loader prompt, enter the reboot command to force the device to boot from the alternate partition:
Type '?' for a list of commands, 'help' for more detailed help.
loader>    
loader>                     
loader> reboot
Resetting...

U-Boot 2011.06 (May 14 2017 - 04:37:09), Build: jenkins-DEV_X_141_X53_BRANCH-vjqfd-972
  • The device should boot up with the latest image.
  • After successfully booting with the latest image, execute the following command to snapshot the latest image to the alternate partition, which previously had the old image:
request system snapshot slice alternate all-members

Modification History

12/09/2023-Publishing the Article

18/09/2023-Changed Format install article from internal to external