Restrictions for Controlling Switch Access with Passwords and Privileges
The following are the restrictions for controlling switch access with passwords and privileges:
Disabling password recovery will not work if you have set the switch to boot up manually by using the boot manual global configuration command. This command produces the boot loader prompt (switch:) after the switch is power cycled.
Restrictions and Guidelines for Reversible Password Types
Password type 0 and 7 are replaced with password type 6. So password type 0 and 7, which were used for administrator login to the console, Telnet, SSH, webUI, and NETCONF must be migrated to password type 6. No action is required if username and password are type 0 and 7 for local authentication such as CHAP, EAP, and so on.
Type 6 encrypted password is supported from Cisco IOS XE Gibraltar 16.10.1 and later releases. Autoconversion to password type 6 is supported from Cisco IOS XE Gibraltar 16.11.1 and later releases.
If the startup configuration has a type 6 password and you downgrade to a version in which type 6 password is not supported, you can/may be locked out of the device.
Restrictions and Guidelines for Irreversible Password Types
Username secret password type 5 and enable secret password type 5 must be migrated to the stronger password type 8 or 9. For more information, see Protecting Enable and Enable Secret Passwords with Encryption.
If the startup configuration of the device has convoluted type 9 secret (password that starts with $14$), then a downgrade can only be performed to a release in which the convoluted type 9 secret is supported. Convoluted type 9 secret is supported in Cisco IOS XE Gibraltar 16.11.2 and later releases. If the startup configuration has a convoluted type 9 secret, and you downgrade to a release prior to Cisco IOS XE Gibraltar 16.11.2, you can/may be locked out of the device.
Before you downgrade to any release in which convoluted type 9 secret is not supported, ensure that the type 9 secret (password that starts with $9$) must be part of the startup configuration instead of convoluted type 9 secret (password that starts with $14$) or type 5 secret (password that starts with $1$).
If a device is upgraded from Cisco IOS XE Fuji 16.9.x, Cisco IOS XE Gibraltar 16.10.x, or Cisco IOS XE Gibraltar 16.11.x to Cisco IOS XE Gibraltar 16.12.x, the type 5 secret is auto-converted to convoluted type 9 secret (password that starts with $14$). For example:
username user1 secret 5 $1$dNmW$7jWhqdtZ2qBVz2R4CSZZC0is auto-converted to
username user1 secret 9 $14$dNmW$QykGZEEGmiEGrE$C9D/fD0czicOtgaZAa1CTa2sgygi0Leyw3/cLqPY426. After the device is upgraded, run the write memory command in privileged EXEC mode for the convoluted type 9 secret to be permanently written into the startup configuration.
Plain text passwords are converted to nonreversible encrypted password type 9.
This is supported in Cisco IOS XE Gibraltar 16.10.1 and later releases.
Secret password type 4 is not supported.