Console from Cisco Router Aux Port
This post is mostly for me to refer to later, or perhaps for folks looking on Google. The issue I run into sometimes is that I need to console into a Cisco device that is in a different geographic location than I am. Usually I have a syslog machine that I have the local IT guys hook up to the serial port - but in some places I don’t have all of that set up.
Here’s how I set up a console connection from a 2821 router’s Aux port to a switch:
- Hook up a rollover cable from the Aux port on the router to the console port on the device that you want to connect.
- Put the following configuration in under “line aux 0″
line aux 0
modem InOut
transport input all
stopbits 1
flowcontrol hardware - Create a loopback interface, you will use this to do the reverse telnet.
interface Loopback0
ip address 172.17.2.1 255.255.255.252 - Run “show line” to figure out which line the Aux port on your router lives on.
- Note the line number (mine is 1 here) - add 2000 to that. In my case I come up with 2001.
- Now, telnet into the loopback address with the number you came up with afterward - telnet 172.17.2.1 2001 (note a lot of resources tell you to do ip:port but space was how it worked for me here and on a 1700 series router as well).
- You should now be consoled in!
Supposedly you should be able to exit by hitting ctrl+alt+f6. This doesn’t work for me (might be my Mac keyboard). The way I exited was to telnet into the router and put in clear line 1 (or use whatever your line number is).
This came in very handy for me yesterday, and I know there will be times in the future that it will be handy in the future.
many many thanks to you
Also, many many thanks!!!!
Cheers mate!
hey, i bumbed into an issue:
I have used the method before and I was successful, now trying in a new device, all goes fine, session openes but it will not go further than OPEN:
[OK]
ITDTC-70004-A00RT001#telnet 10.87.128.246 2001
Trying 10.87.128.246, 2001 … Open
any ideas?
I had the same issue.. It just does not go further .. Do we need to set the speed some where ??
Adriano and kabb,
I ran into the same issue last Friday. I had a router that I was configuring a few switches for a new buildout at one of my company’s locations and all of a sudden it stopped working. I rebooted the router that night and it started working again. Strange I know.
kabb, you can set speed on the aux port. It defaults to 9600 so the only reason you should need to set it is if you set the console port of whatever you are trying to get into to something else.
WOW it works dude !!!
Thx a lot for infor
NO need to create a loop back interface to connect through console to aux OR vise versa. I have connected two 2800 series routers by just crossing aux to console with the following commands in each side
line con 0
login local
line aux 0
login local
modem InOut
transport input all
flowcontrol hardware
you can telnet the internal interface of the router with 2000+line number. e.g
telnet 192.168.10.1 2001
where line number is 1 for aux.
You can also use the
ip host
bu using this command you can connect the other box with the box name
Cool, I didn’t know this. I’ll give it a shot, actually have a router that someone just hooked up for me between current router’s aux and console on the new router that is waiting for me to configure… Thanks!
Joe, thanks for the posting.
Adriano and Kabb,
to overcome the issue no need to reboot,
just add the command ‘no exec’ eg
line aux 0
modem InOut
no exec
transport input all
stopbits 1
flowcontrol hardware
there’s a complicated explanation why it works, but it does.
cheers
Phil
This just helped me in configuring 2 classroom switches in Concord!!!