Run the command to make the RIP authentication valid

RIP version 1 does not support authentication. If version 2 is received and sent, the interface can perform RIP authentication.
A key link determines a series of keys that can be used for interfaces. If the key link is not configured, the interface cannot perform authentication, or even the default authentication.

Cisco supports two interface authentication modes that enable RIP authentication: plain text authentication and MD5 authentication. The Default Authentication Mode of the RIP package is plain text authentication.
Note: because each RIP packet sends an unencrypted authentication value, do not use plain text authentication for the sake of security. When security is not a problem, for example, to ensure that the set host does not participate in route selection, you can use plain text authentication.
To set RIP authentication, run the following command in Interface Configuration Mode:

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