Cisco Routers for the Desperate, 2nd Edition

Passwords

A password is the simplest authentication method a Cisco router can use, but it's effective enough for most networks. If you have dozens of routers, you may want to consider a solution such as RAIDUS or TACACS+, but that really is overkill for small environments. By default, routers do not require passwords, but also by default, you cannot access the router over the network, so in order to get a command prompt on the router, you need physical access. Cisco assumes that if you know enough to enable network access, you know enough to set up passwords.

Before implementing passwords on your router, make certain that the password encryption service is activated. By default, routers store passwords in their configuration in unencrypted format. ...