VTY Lines

Hi,

When doing a show run is there a particular reason VTY lines are split into 2 sections and not just show vty 0 15 under one line? I'm just having a go at setting telnet passwords etc.. and noticed thi.

line vty 0 4
password
login
line vty 5 15
password
login

Thanks

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Comments

JockVSJock

Its my understanding that the VTY or Virtual Terminal Lines are a type of TTY that are used to control inbound Telnet sessions. They are based off of software, so they are virtual, not a hardware thing and show up as line vty 0 4.

The newer types of IOS allow for more then just the 5 connections (line vty 5 15).

So that is why you see two entries for line vty.

fluk3d

control wrote: »

Hi,

When doing a show run is there a particular reason VTY lines are split into 2 sections and not just show vty 0 15 under one line? I'm just having a go at setting telnet passwords etc.. and noticed thi.

line vty 0 4
password
login
line vty 5 15
password
login

Thanks

Usually they are split up to be setup as rotary authentication. One can be using clear text login, and the other group could be using AAA/Local database (username/password)

SubnetZero

The reason they're split up in the configuration is for backward compatibility with older IOS versions.

In the olden days the IOS only supported 5 VTY lines (0 to 4) but in newer versions of IOS the number was increased to 16 (0 to 15) and eve more if you have some newer IOS code running.

In this way the "line vty 0 4" will be accepted by all IOS versions and the remaining lines line "vty 5 15" will be accepted by newer IOS versions.

HTH