factory-reset: clear hostname and ssh keys, and reset motd banner

[anamehra]

Signed-off-by: Anand Mehra (anamehra) [email protected]

Why I did it

Factory reset does not clear ssh keys and hostname file.
Motd banner is not reset to factory default

Work item tracking

• Microsoft ADO (number only):

How I did it

• Remove SSH host keys (will be regenerated on fresh boot)
• Remove hostname (will be set on fresh boot)
• Add reset motd banner to factory default

How to verify it

Run reset-factory command

root@yy39-lc1:/home/admin# reset-factory 
Stop critical services
Reset banner/motd file
MOTD restored from factory default
Removing hostname (will be set on boot)
Call config-setup factory
Remove non-default users
Restore default users passwords
Remove SSH authorized keys from all users
Remove SSH host keys from /etc/ssh
Delete bash, python and vim history files
Delete any non-dotfiles in users home directories
Remove all docker containers except the database
Clear sonic directory
Clear warmboot folder
Delete reboot-cause files and symlinks
Delete tech-support files
Delete logs files
Error response from daemon: No such container: syncd0
Error response from daemon: No such container: syncd1
Error response from daemon: No such container: syncd2
Watchdog armed for 300 seconds
1
Error response from daemon: No such container: syncd0
Error response from daemon: No such container: syncd1
Error response from daemon: No such container: syncd2
fstrim: /mnt/obfl_mnt_dir: the discard operation is not supported
/var/log: 3.8 GiB (4040876032 bytes) trimmed on /dev/loop1
/host: 4.2 GiB (4512677888 bytes) trimmed on /dev/sda3
Watchdog armed for 300 seconds
Wed Nov 19 04:35:28 PM UTC 2025 Rebooting with platform x86_64-88_lc0_36fh-r0 specific tool ...
Connection to 10.175.46.7 closed by remote host.
Connection to 10.175.46.7 closed.


Debian GNU/Linux 12 localhost ttyS0

localhost login: admin
Password: 
Linux localhost 6.1.0-29-2-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.123-1 (2025-01-02) x86_64
You are on
  ____   ___  _   _ _  ____
 / ___| / _ \| \ | (_)/ ___|
 \___ \| | | |  \| | | |
  ___) | |_| | |\  | | |___
 |____/ \___/|_| \_|_|\____|

-- Software for Open Networking in the Cloud --

Unauthorized access and/or use are prohibited.
All access and/or use are subject to monitoring.

Help:    https://sonic-net.github.io/SONiC/

admin@localhost:~$ 

sonic@sonic-ucs-m6:~$ ssh [email protected]
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    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.
The fingerprint for the RSA key sent by the remote host is
SHA256:xs5Wqa985LuxKxzuxwWuF4JX04atz+mCzrBvyv5b7l0.
Please contact your system administrator.
Add correct host key in /home/sonic/.ssh/known_hosts to get rid of this message.
Offending RSA key in /home/sonic/.ssh/known_hosts:41
  remove with:
  ssh-keygen -f "/home/sonic/.ssh/known_hosts" -R "10.175.46.7"
Password authentication is disabled to avoid man-in-the-middle attacks.
Keyboard-interactive authentication is disabled to avoid man-in-the-middle attacks.
Debian GNU/Linux 12 \n \l

[email protected]: Permission denied (publickey,password).

Which release branch to backport (provide reason below if selected)

• 202205
• 202211
• 202305
• 202311
• 202405
• 202411
• 202505

Tested branch (Please provide the tested image version)

Description for the changelog

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)

[mssonicbld]

/azp run Azure.sonic-buildimage

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Azure Pipelines successfully started running 1 pipeline(s).

[mssonicbld]

/azp run Azure.sonic-buildimage

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[prgeor]

@qiluo-msft can you please review?

[mssonicbld]

/azp run Azure.sonic-buildimage

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).