VTY access trivia.

You have a problem with an edge router at a remote site. When working with a representative from the ISP you give him the telnet password for the router. After the rep restores connectivity he informs you that he did not need the password to get access to the router.

Why would this happen?

Find more posts tagged with

Save $250 on 2025 certification boot camps from Infosec!

Book now with code EOY2025

Button

Comments

KMAN24

This seems to easy but could the VTY have been set to no password.

Line VTY 0 4
login
password

???

sbenjamin

If you use the login command but set the password to nothing you will get an error when you log into the router. It will say something about a login is required but the password has not been set and then it will close the telnet session. I also noticed I got a message when I entered the login command before setting a password it said you have to enter the password first, so you would have to set the password, do the login command and then set the password to nothing to have this problem

kplab

By default, virtual terminals require a password. If you do not set a password for a virtual terminal, it responds to attempted connections by displaying an error message and closing the connection. This feature protects the router from unauthorized remote access. However, you can disable password checking and allow connections without a password using the command "(config-line)#no login".

For details, refer to:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/tersv_r/ter_l1g.htm#wp998262

nethead

I've always found that you can't telnet into a router unless a password is set, otherwise you get "password required but none set".

Paddington

You can use the command no login to get that function

tunerX

Paddington wrote:

You can use the command no login to get that function

You are correct.