hi
There are different methods like configuring an ACL allowing only to accept from trusted ip blocks and applying the access-class in under the line vty.
Also you can set the timeout period to avoid unecessary telnet session to hang on for hours.
Also if you desire configure only SSH access instead of the plain old telnet access.
Get the users authenticated from either external TACACS Server and also set different privilege levels of the users.
regds
