Switches, Hubs, and Modems

Console access while using MRTG

Go to solution
Jeff Mesch
Occasional Contributor

Console access while using MRTG

I recently started running MRTG to collect SNMP data from my Procurve 4000m and 2424m switches. It is working fine, doing everything I need it to do.

However, now that I have MRTG running to pull data every 5 minutes, I am no longer able to access my switches via telnet or the web. The last time I worked with them before turning on MRTG I was able to access them via Telnet and the web.

Now when I try via Telnet, it says it connects, then gives "Escape character is '^]'." then terminates with "Connection closed by foreign host."

Halting the cron job for a few minutes did not change anything.

Is there something I'm missing here?

Ron Kinner
Honored Contributor

Re: Console access while using MRTG

Did you have passwords configured on the switches before you turned SNMP on? If I read the manual correctly the thing doesn't need passwords at first but once one is assigned then you need them. Could be that assigning a community string was considered assigning a password and now you need to go back in through the console and assign passwords.

In any event you need to go back in with the console to each switch and make sure you have assigned passwords. Page 7-7

Then do:

show ip authorized-managers

If you see anything then you will need to add your own IP address to the list as per p7-35


Jeff Mesch
Occasional Contributor

Re: Console access while using MRTG

That's a thought.

However, my problem is just getting into the console right now. I have not had console access since I started running MRTG.
Ron Kinner
Honored Contributor

Re: Console access while using MRTG

Following posted by Arimo:

"If you press RESET you will reboot the switch. No settings will be lost.

If you press CLEAR you will clear all passwords of the switch. Nothing else.

To lose switch settings you need to press both together in a sequence described in Management and Configuration Guide.

So, just press Clear and try again :-)


That's not how I read the manual but I've never had one to play with. Just Cisco stuff which this seems to be derived from.

I wonder if when you turned SNMP on for MRTG if you didn't let a hacker in who changed your passwords. It appears that the default of public may have write access to the system at least they talk about setting it to restricted if you have security concerns. With the right set of MIBS and a program which can read and set SNMP variables you can do all sorts of harm. (You might also be able to fix your problem. There is a Perl module which lets you do SNMP sets: http://search.cpan.org/author/WMARQ/SNMP-Util-1.8/Util.pm )

Romeo Chance
Occasional Advisor

Re: Console access while using MRTG


You dont have console access (via serial port)?

You should always get console access
via the serial 9600,N,8,1

Once you get access that way, go and
change/set the password immediately.
If u dont have the password, then
press the CLEAR button infront of switch.
This clears the password only, not the config.

Also check IP Authorized Managers
as it may have something filled (IP address)
which is not what u have on your PC...

Fillin your IP address of your PC and also
the one for the MRTG machine...

hope that helps

Jeff Mesch
Occasional Contributor

Re: Console access while using MRTG

Problem resolved. Answer was simple, it was just a Monday after a holiday weekend, so I overlooked something basic.

Under "Switch Management Access Configuration...", for whatever reason, I set only 1 "IP Authorized Manager". The IP I entered was for the machine running MRTG, and not the machine I typically use to connect to the switches.

I went in via the machine running MRTG and fixed the problem.

Thanks to all those with suggestions.