"transport input none"?

[saidfrh]

Hi,

What is the command "transport input none" for? The above is configured on Line con 0.

Thanks.

Said

[sundar.palaniappan]

It disables access to console 0 as it prevents any protocol selection on the line. This makes the port unusable by incoming connections.

--Sundar

[saidfrh]

Sundar,

Does "transport input none" not allow me to console in to the router and change configs...? If the above is true, the the only way to access the router is using telnet or aux port--am I correct?

Said

[naveed.ali]

we had experience similar issue and found the solution to put the line console 0 to default or allowed all

line console 0

default transport input

or line console 0

transport input all

[saidfrh]

Thanks.

[Richard Burts]

I have seen transport input none configured on vty lines and the behavior is as Sundar describes that it prevents access to the vty lines. I was not sure that it works the same on the console (I believe there is a different behavior for tty than for vty). So I attempted to configure transport input none on a console port. I got an invalid command response. So I do not believe that this command works on console ports.

HTH

Rick

[andrew.butterworth]

When applied to the console or Aux ports it stops reverse-telnet connections to these ports, it won't stop you physically connecting a console and logging into the router. To prevent anyone getting access to the router CLI (the exec) on these ports you can turn off the exec process on these lines:

line aux 0

no exec

HTH

Andy

[saidfrh]

Andrew,

Excuse my ignorance, but how do you reverse-telnet to a console port?

Thanks.

Said

[andrew.butterworth · Accepted solution]

By default cisco routers will allow telnet connections to TTY lines on TCP ports 2000 + the line number. For example the AUX port on a router is usually TTY 5, therefore if you telnet to the router but use destination TCP port 2005 you will connect to the router but the input will be directed to the AUX port. This gives you Terminal Server capabilities and is commonly used to connect to router/switch console ports via a router with a multiport async card (NM-32A etc).

I have seen some routers that don't allow inbound connection to the console port (transport input command isn't supported on the con 0 line), others it seems to work - probably an IOS thing...

Have a look on CCO for reverse telnet for more information.

HTH

Andy

[saidfrh]

Andrew,

Thanks.

Said