If you want to increase the number of VTY ports available on the router for remote access, create a reference to the additional lines in the configuration as follows:

Router1#configure terminal 

Enter configuration commands, one per line.  End with CNTL/Z.

Router1(config)#line vty 0 9

Router1(config-line)#exit

Router1(config)#end

Router1#

This command defines the characteristics for a range of VTY ports from 0 to 9. Since ports 0 to 4 exist by default, this has the effect of creating ports 5 through 9.

By default, most Cisco routers provide five virtual terminals (VTYs) for remote access. Often the default number of VTYs is not sufficient and increasing the number can be quite useful. This is particularly true in lab or training environments that require a large number of concurrent sessions on a particular router.

The router can support up to 181 virtual terminals. However, it is extremely rare to actually need more than about 20. Keep in mind that additional virtual terminals will utilize system resources, so don't go over board. You must explicitly configure all of the new VTY lines with passwords, access-classes, exec-timeouts, transport protocols, and so forth.

To view the newly created VTY terminals, use the show users all EXEC command:

Router1#show users all

    Line       User       Host(s)              Idle       Location

   0 con 0                                     00:00:00 

  65 aux 0                                     00:00:00 

  66 vty 0     ijbrown    idle                 01:15:29 freebsd.oreilly.com

  67 vty 1     kdooley    idle                 00:12:17 freebsd.oreilly.com

* 68 vty 2     weak       idle                 00:00:00 freebsd.oreilly.com

  69 vty 3                                     00:00:00 

  70 vty 4                                     00:00:00 

  71 vty 5                                     00:00:00 

  72 vty 6                                     00:00:00 

  73 vty 7                                     00:00:00 

  74 vty 8                                     00:00:00 

  75 vty 9                                     00:00:00 

  Interface      User        Mode                     Idle     Peer Address

Router1#

There are five new VTY lines available on this router (VTY 59).

To remove the newly created VTY lines, use the no version of the command:

Router1#configure terminal 

Enter configuration commands, one per line.  End with CNTL/Z.

Router1(config)#no line vty 5

Router1(config)#end

Router1#show users all

    Line       User       Host(s)              Idle       Location

   0 con 0                                     00:00:00 

  65 aux 0                                     00:00:00 

* 66 vty 0     ijbrown    idle                 00:00:00 freebsd.oreilly.com

  67 vty 1                                     00:00:00 

  68 vty 2                                     00:00:00 

  69 vty 3                                     00:00:00 

  70 vty 4                                     00:00:00 

  Interface      User        Mode                     Idle     Peer Address

Router1#

You cannot create or delete VTY lines out of order. Adding VTY line 20 will automatically create lines numbered from 5 to 20. Similarly, removing VTY line 5 will implicitly remove all lines above line 5 (as illustrated in the previous example).

The router will not allow you to remove the original five virtual terminals. If you do attempt to delete them, the router will produce the following warning message:

Router1#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router1(config)#no line vty 4

% Can't delete last 5 VTY lines

Router1(config)#end

Router1#