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General Router FAQ

Using Telnet

How do I produce Telnet diagnostic logs ?

When analysing a problem, or simply trying to learn more about your router, it is sometimes useful to produce or view logs that the router can produce. These are several types of log, and they are all accessed via the Telnet interface (for information on accessing the Telnet interface, see here.

The commands vary with each router, but these are the general ones :

The logging function runs continuously (you do not need to enable it specifically) so it will contain a lot of data after a while. If you want to log a specific event, you should flush (clear) the logs before you initiate that event. Do this with the command log -F a

The most commonly used log is the call log (log -c), which will show any problems with logging in to your ISP or a VPN login error, for example if you had your username or password wrong (for an ISP that is normally indicated by the message "CHAP Login Failed". The example below shows the call log of a router which has logged into the ISP successfully (on ADSL) and then a teleworker has dialled into the router:

ADSL Telnet Logs

The next example log shown shows a successful call on an ISDN Router (e.g. Vigor2800i), and you can determine some useful formation from it. You can see that it dials twice, and gets a busy signal twice, then on the third attempt, it connects to the ISP, the authentication goes through and then a couple of minutes later, the call is cleared due to inactivity. You can also see whose PC triggered the call – in this case it was which happens to be a local mail server:

ISDN Telnet Call Logs

How do I open a Telnet session to the router ?

The Web User Interface (WUI) is your normal method for configuring and checking status of the router. The Telnet interface is a 'command line' type interface which gives a prompt at which you enter commands line by line, according to command syntax. The scrolling display method is ideal for longer diagnostic log output compared to fixed pages of the WUI.

Although WindowsXP/2000 has a default simple Telnet program, it is 'DOS/Console' based, which makes capturing of output difficult (for example to send logs to an engineer). We therefore recommend using the Windows Hyperterminal program instead, which is standard in Windows. Run it from the Start Menu:

When the program loads, select TCP/IP like this :


The Telnet session should start and once past the router password, you can enter your required commands, for example 'sys ver' displays the router's firmware version:

Telnet Session Active

A text capture will store all of your session to a text file which you can view later, or send to an engineer for analysis. Start a text capture from the menu:

Hyperterminal Text Capture

At the end of your session, select 'Stop Capture' from the same menu or just exit Hyperterminal to stop the text capture.

In Windows 95/98/ME the default Telnet program can be used instead. Press the Start button, then Run, then enter TELNET.EXE (assuming that's the router's IP address) and the telnet program will open.

Telnet Example

For other operating systems, suitable Telnet programs are either included or available on the Internet as free downloads.

Using Hyperterminal for Console (RS232) connections

This applies to the Vigor2000 only.

The Vigor2000 router has a console (RS232/serial) port which can be used to communicate with the router, upgrade firmware etc. To access it, use the GREY cable into the console port and a COM/Serial port on your PC. The Vigor2200 range does not have a console port.

From the Windows START button, go to Programs/Accessories/Communications and locate the windows Hyperterminal mail program :

Double click on the icon to start the program and you should see a series of setup screens as follows :


Select "Direct to Com X" where ‘X’ is the COM port you’re using on the PC and select 115200 bps for the serial speed. When all is well, the Vigor console menu will appear :

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