Telnet

The following five commands all achieve the same resultthe attempt to connect remotely to the router named paris at IP address 172.16.20.1.

Denver>telnet paris
Enter if ip host command was used previously to create a mapping of an IP address to the word paris
Denver>telnet 172.16.20.1

Denver>paris
Enter if ip host command is using default port #
Denver>connect paris

Denver>172.16.20.1

Any of the preceding commands lead to the following configuration sequence:

Paris>
As long as vty password is set. See Caution following this table

Paris>exit
Terminates the Telnet session
Denver>

Paris>logout
Terminates the Telnet session
Denver>

Paris>, release, then press
Suspends the Telnet session, but does not terminate it
Denver>

Denver>
Resumes the connection to paris
Paris>

Denver>resume
Resumes the connection to paris
Paris>

Denver>disconnect paris
Terminates the session to paris
Denver>

Denver#show sessions
Displays connections you opened to other sites
Denver#show users
Displays who is connected remotely to you
Denver#clear line x
Disconnects remote user connected to you on line x
Line number is listed in the output gained from the show users command
Denver(config)#line vty 0 4

Denver(config-line) session-limit x
Limits the number of simultaneous sessions per vty line to x amount

Caution:

The following configuration creates a big security hole. Never use it in a live production environment. Use it in the lab only!

Denver(config)#line vty 0 4
.
Denver(config-line)#no password
Remote user is not challenged when Telnetting to this device
Denver(config-line)#no login
Remote user moves straight to user mode

Caution:

A device must have two passwords for a remote user to be able to make changes to your configuration:

Line vty password (or have it explicitly turned off; see previous Caution)
Enable or enable secret password

Without the enable or enable secret password, a remote user will only be able to get to user mode, not to privileged mode. This is extra security.