Comm Servers and the escape characters

[Males]

Hi!

We put up a Comm Server (Cisco 2511) here and we'd like to use it to access many console ports in a telecom room ...it is working properly with one exception: for some reason, if you log on a device, there is no other way to log off than rebooting the Comm server or waiting for the session timeout...I've tried the standard Ctrl-Shift-6-x and numerous other sequences...and so far it doesn't work. Any one has an idea?

[milan.kulik]

Hi,

check the config, there might be

a) username xxxxx noescape

b) line x

escape-character

or

disconnect-character.

Regards,

Milan

[Males]

Did check what you mentionned. Didn't see any of those things. As a matter of fact, the configuration of my Comm Server is almost the same as what they say in the Comm Server paper from Cisco.

The thing is that it once worked (When I first configured it, I tried to test it with a 3500 XL switch and it was working fine.)

With my laptop and with the station we have in that room it just won't work. My desktop is XP, my laptop is Win 98 and the station is Win2k but in the end I always use Hyper Terminal...

So far, the only way I can get out of a reverse telnet is to wait a minute for my session to timeout...and 1 minute is quite long...But there is no way I can make it 15 seconds so....

In any case, thanks for the reply,

M.

[rjackson]

Sometimes the escape sequence on the comm server is changed so it (ctrl/shift/6/x) will work on the router your are connecting to. Ex: If you connect to a router and do a trace you want to kill the cntrl/shft/6/x wont kill the trace it would take you back the the comm server. By changing the escape sequence on the comm server the routers all act normal but you have to use a different sequence to get back to the comm server. I use "escape-char 24" so that a control x/x escapes back to the comm server. The standard is 30 (the ^).

Look at the comm server line config for commands changing the escape character. It will be on the line you enter the comm server on; ie, if you telnet in its o the vty lines or cons in its on the console line. Also you can do a show line on that line to see what the escape character is. Remember, the problem is on the line you enter the server on not the line facing the routers.

[milan.kulik · Accepted solution]

Well,

I'm not sure now if I understand the problem correctly, but the ICND book says:

"To suspend a Telnet session end escape from remote target system back to your local router, press Ctrl-Shift-6 followed by the character x."

But this works only on some IOS target systems.

It doesn't work on CatOS devices, e.g.

So if you are connecting to non-IOS systems, try other escape sequences (Ctrl-C, Ctrl-Break, etc.).

If it doesn't work there should be still the possibility to end the Telnet session from remote device by entering exit, logout, quit, q,... command.

BTW, even if this fails there should be possible to configure "exec-timeout 0 15" to decrease the timeout.

Regards,

Milan

[Males]

Milan,

You do understand the problem, I think.

I know that theorically (and practically on other devices on our network) the Ctrl-Shift-6-x sequence works.

What I want to know is why this is supposed to work and it doesn't.

I can log out, but I'll end up facing the same prompt you would see if you were on the console port of a device, that is, "Press return to start" or sth like that and I will still be on the device that I telnetted.

I configured the session time-out to wait 1 minute and then disconnect. But a minute is long.

I cannot use the "disconnect line X" because one cannot disconnect the console session in use. (Remember, I'm telnetting the console port of a device)

If I could go back to the Comm server, I could kill the session, but I can't.

Do you see what my problem is?

M.

[milan.kulik]

OK,

what is the target device?

Is it an IOS one?

I yes, what is the console line setting (look to the config, use sh line console 0)?

I suppose your comm server is configured regarding http://www.cisco.com/warp/public/793/access_dial/comm_server.pdf.

I'm afraid I need to know the complete config of your comm server t go further.

Regards,

Milan

[Males]

Yes, they are all IOS or CatIOS and my config is almost identical to what is shown in the link you provided (apart from the aliases and ip hosts that don't have the same address and names...)

Issuing a sh ru gove me only "transport input all" for the con 0.

Once again, thanks for your replies, I've been trying to figure this one out for at least a week.

M.

[milan.kulik]

Well,

final idea today:

I'm using Tera Term Pro version 2.3 freeware terminal emulator instead of Hyperterminal. It's behaviour is a little different:

When I Telnet to a IOS device and then issue a quit command, the connection is closed, the Telnet connection is really terminated, no prompt after a new enter as while using Hyperterminal.

Maybe this might help.

I'm not having any Cisco console connected to comm server at the moment, so I'm not able to make any test. But maybe next week I'll have some time to play with it.

Regards,

Milan

[Males]

Thanks Milan...Unfortunately I've tried Tera Term (had been a while since the last time I used it.) and it doesn't change a thing.

I'm starting to consider setting up things so that I can telnet "reverse reverse" and kill my own session.

M.

[milan.kulik]

Hi,

what about this stupid idea:

Simply close Hyperterminal window (Alt-F4) ?

Milan

[Males]

Milan,

That was a good idea and I hadn't thought about it...But unfortunately it doesn't work either. I always wind up on the same place I telnetted and then I have to wait for the session to time out.

M.

[rmcarthur]

If you can identify the particular session using the show sessions command, you can then issue the command disconnect x, where x is the session number.

HTH

[rjackson]

When you first connect to the comm server do a show line. See what line you connected on (like vty0 if you telnet'd to it). Then sho line vty0 (or use the absolute line you connected on). It will tell you what the escape sequence is under a line that says Special Characters. When it reads ^^x the first ^ is the ctrl key, the second ^ is the shift/6, the x is the x. I think of it as the terminator. If it doesnt show ^^x then figure out what the sequence is set to or set it to something else. You dont want it to be ctrl/shft/6/x because then you cannot use that sequence when you are talking to a router though it. The only purpose for the shift in the standard sequence is because they want the ^ character. It could be read as ctrl^x. If it does say ^^x then you have a problem with your emulator or your keying. Are you holding the ctrl and shft when you press the 6? then release them and press x.

[Males]

Ok, here's the deal:

When I first log in the Comm Server, I'm on con 0.

When I telnet in on a line (1 16).

All of those lines and the con have an escape sequence of ctrl/shft/6/x, or let's say, the default value.

I've tried to change the sequence many times, used a different terminal and almost all of Milan's suggestions and still it doesn't work.

Even if I close HyperTerm and then open it again I'm still on the telnetted device. Unless I wait till the session limit there is no way to disconnect from the telnetted device.

The reason why I cannot live relying on the session time-out is that usually if we are using the console there is some kind of emergency going on. If the campus is cut from the web let's say, I'll be really mad if I have to wait a minute to disconnect from my session.

If there was such a thing as a session timeout after 15 seconds of inactivity on the line, I would take that and live with it, but not 1 minute.