Remote monitoring with SSH

[Thorinson]

Hi,

I'm new to Cacti and have already searched the whole forum but can't find any solution for my SSH problem.

I'm trying to get disk space data from a remote-host using SSH and a perl script. All machines are running under linux.
If I call the command "/usr/bin/ssh root@aHost -C /usr/local/cacti/scripts/diskused.pl aPartition" at the shell, it returns the right values (total:12345678 used:23456789). Using Cacti the following can be read in my cacti.log:
"WARNING: Result from CMD not valid. Partial Result:
CMD: /usr/bin/ssh root@aHost -C /usr/local/cacti/scripts/diskused.pl /, output: U".
I've checked the Maximum Value of my Data Source Item, but it's big enough to hold the returned value.

Here's the perl script:

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#!/usr/bin/perl

$ret = `df --block-size=1024 -P $ARGV[0] | grep -v Filesystem`;
$ret =~ s/($ARGV[0])(.* )(.*[0-9])(.* )(.*[0-9])(.* )(.*[0-9])(.* )(.*[0-9])%(.* )//;

print "total:$3 used:$5";

What could be the problem ?

Tnx in advance,
Thorinson

[rony]

Check that the user that the poller is running as has the public private keys setup and that there is an entry in known_hosts for that users. Otherwise, it could be prompting, either to save the host key, or for a password.

[Thorinson]

I've already placed a public key on that host and as I mentioned above the command works when using the shell. There's no promting, neither for a key, nor for a password. It must be another problem ... but tnx.

[gninja]

You may want to add in the full path to df and grep in your script.

If that doesn't work, a couple debugging tricks you can try are adding an

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`/usr/bin/touch /tmp/ssh-works`;

Then wait a polling interval, if that file's in /tmp afterwards then ssh works.

And what you could do at that point is write a quick wrapper that calls your ssh command, outputting to a file, and then cats the last line of that file (which should be your print command.) like:

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#!/bin/sh
/usr//bin/ssh  user@host -C /usr/local/cacti/scripts/diskused.pl / 2>&1 > /tmp/sshoutput
tail -1 /tmp/sshoutput

And if it works, it works. if not, you've got the full output saved in a file that you can view. Dirty, but should be helpful