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1811 as a terminal server?

I've heard that you can configure an 1811 router as a terminal server for remote console work.

I have several of them in the lab and would love to try it out.

Has anyone done this?

Thanks!

Ven                  

Ven Taylor
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Cisco Employee

1811 as a terminal server?

Easy to do.. just use the AUX port (BTW, this can be done using any Cisco IOS router that has an AUX port).  For the 1811, I suggest the following (this is how I normally do it):

! presume you have aaa new-model configured

aaa new-model

! suggest making a "none" type of method for login

aaa authentication login my-none none

! configure the aux port

line aux 0

  ! this is just a sanity setting to force a port release every 60 mins.  remove this if you want long lived

  !  terminal server sessions, or adjust as needed

session-timeout 3600

  ! this will prevent the 1811 itself from soliciting a login on the reverse telnet session.  if you want the 1811

  !  to enforce a login (aka if you want to protect the attached device via an 1811 based login sequence),

  !  then adjust this to a different aaa login method.  In my case, I enforce login on the attached serial device

  !  and find having the IOS 1811 doing a login to be a nusiance.

login authentication my-none

! subtle but important step here.. turn off the aux line "exec" processing.  if you do not do this, it will still work

!  but when you connect, do not be surprised to find a ton of junk coming out... as if the exec is on, the anytime

!  the attached device output.. aka inputs to the aux.. then the "exec" will try to process it like an IOS CLI command.

no exec

! at minimum, one has to allow telnet (as that is really the only thing that can attach via reverse telnet)

transport input telnet

! adjust this if needed, note 9600 baud is the default so it will not show up

speed 9600

Also suggest the following:

! putting this at the top of the global config will help prevent "hung" sessions.  basically if

!  someone abruptly disconnects, within 5 mins the reverse-telnet session will be released on the

!  1811.  aka, prevents one from having to do tedious "clear line" on the 1811 for a hung reverse-telnet

service tcp-keepalives-in

Once you have this in place.. do a "show line"

1811#show line

   Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int

      0 CTY              -    -      -    -    -      0       0     0/0       -

      1 TTY              - inout     -    -    -      0       0     0/0       -

      5 AUX   9600/9600  -    -      -    -    -      3       0     0/0       -

The AUX port should be line "5" on an 1811.  As such, the reverse-telnet port to use for this port is "2005" (aka 2000 + line#).  Thus do a telnet to your 1811, but change the TCP port from 23 to 2005.

QED.

~G

the

Cisco Employee

1811 as a terminal server?

PS.  Expect you realize.. cable should be just a normal "roll over" mod8 cable to go to another Cisco console port.

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