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problem with nrpe and ubuntu

PostPosted: Thu Jul 06, 2017 8:17 am
by majed
Health be upon you,
today I installed an ubuntu with nrpe and it worked because I enabled the root user.
On 3 previous ubuntu's, it is not working because the root is disabled.
here is the error:
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cd /usr/lib/nagios/plugins/
@NE8:/usr/lib/nagios/plugins$ sudo -s -u nagios ./check_nrpe -H 127.0.0.1 -c check_disk
NRPE: Unable to read output

I researched the error and it is narrowed to:
either the path nrpe.cfg is wrong or there is a permission problem.
according to
https://serverfault.com/questions/323233/nrpe-unable-to-read-output-but-why
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nagios ALL=(ALL) NOPASSWD:/usr/lib/nagios/plugins/

must be added to the sudoers file.
I am reluctant to do that as in the past i played with the sudoers file and it stopped being accessed! I had to use the ubuntu cd to edit it and this is dangerous in a production environment.
do you confirm that this is the problem?

config of /etc/nagios/nrpe.cfg
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allowed_hosts=127.0.0.1, 10.10.10.12

command[check_users]=sudo /usr/lib/nagios/plugins/check_users -w 5 -c 10
command[check_load]=sudo /usr/lib/nagios/plugins/check_load -w 15,10,5 -c 30,25,20
command[check_disk]=sudo /usr/lib/nagios/plugins/check_disk -w 20% -c 10% -p /dev/sda3
command[check_zombie_procs]=sudo /usr/lib/nagios/plugins/check_procs -w 5 -c 10 -s Z
command[check_total_procs]=sudo /usr/lib/nagios/plugins/check_procs -w 150 -c 200
command[check_swap]=sudo /usr/lib/nagios/plugins/check_swap -w 20 -c 10
command[check_mem]=sudo /usr/lib/nagios/plugins/check_mem.pl -u -w 80 -c 90
command[check_cpu]=sudo /usr/lib/nagios/plugins/check_cpu.sh -i 5 -w 80 -c 90

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ls -l /etc/nagios
total 20
-rwxr-xr-x 1 nagios nagios 8240 июл  5 12:56 nrpe.cfg
drwxr-xr-x 2 nagios nagios 4096 май  8 19:01 nrpe.d
-rwxr-xr-x 1 nagios nagios  117 май  8 19:00 nrpe_local.cfg

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ls -l /usr/lib/nagios/
total 4
drwxr-xr-x 2 nagios nagios 4096 июл  5 12:24 plugins


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sudo ps cax | grep nrpe
12473 ?        Ss     0:00 nrpe

Re: problem with nrpe and ubuntu

PostPosted: Thu Jul 06, 2017 4:21 pm
by tmcdonald
Can you verify the NRPE version and installation method? If it was not compiled from source obtained on our GitHub then it might be an older version with known/unknown bugs depending on the packager/maintainer.

Re: problem with nrpe and ubuntu

PostPosted: Fri Jul 07, 2017 4:12 am
by majed
here is how it was installed:

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sudo apt-get install openssl nagios-nrpe-server nagios-plugins nagios-plugins-basic nagios-plugins-standard


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$ sudo  -s -u nagios ./check_nrpe -H 127.0.0.1
NRPE v2.15

Re: problem with nrpe and ubuntu

PostPosted: Fri Jul 07, 2017 11:52 am
by scottwilkerson
In /etc/nagios/nrpe.cfg you have all the checks prefaced with sudo

you shouldn't need this with most, but if you do have it in there you would need to add the sudo permissions to your sudoers file.

To start with, I would remove sudo from the commands in , restart nrpe and try to make the connection from 10.10.10.12

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sudo -s -u nagios ./check_nrpe -H IP_OF_MACHINE_WITH_NRPE -c check_disk

Re: problem with nrpe and ubuntu

PostPosted: Mon Jul 10, 2017 1:06 am
by majed
ok i removed sudo:
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command[check_users]=/usr/lib/nagios/plugins/check_users -w 5 -c 10
command[check_load]=/usr/lib/nagios/plugins/check_load -w 15,10,5 -c 30,25,20
command[check_disk]=/usr/lib/nagios/plugins/check_disk -w 20% -c 10% -p /dev/sda1
command[check_zombie_procs]=/usr/lib/nagios/plugins/check_procs -w 5 -c 10 -s Z
command[check_total_procs]=/usr/lib/nagios/plugins/check_procs -w 150 -c 200
command[check_swap]=/usr/lib/nagios/plugins/check_swap -w 20 -c 10
command[check_mem]=/usr/lib/nagios/plugins/check_mem.pl -u -w 80 -c 90
command[check_cpu]=/usr/lib/nagios/plugins/check_cpu.sh -i 5 -w 80 -c 90

restarted nrpe..
sysadmin@NS5:/usr/lib/nagios/plugins$ sudo -s -u nagios ./check_nrpe -H 127.0.0.1 -c check_disk
NRPE: Unable to read output
looks like the next step is to add to sudoers file. but i'll be patient and hear what you have to say.

Re: problem with nrpe and ubuntu

PostPosted: Mon Jul 10, 2017 10:11 am
by scottwilkerson
Just to verify I would confirm you can run this as the nagios user first:
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sudo su nagios -c "/usr/lib/nagios/plugins/check_disk -w 20% -c 10% -p /dev/sda1"

Re: problem with nrpe and ubuntu

PostPosted: Tue Jul 11, 2017 1:07 am
by majed
:~$ cd /usr/lib/nagios/plugins/
:/usr/lib/nagios/plugins$ ./check_disk -w 20% -c 10% -p /dev/sda1
DISK OK - free space: / 6835 MB (70% inode=82%);| /=2819MB;8156;9176;0;10196
:/usr/lib/nagios/plugins$ sudo su nagios -c "/check_disk -w 20% -c 10% -p /dev/sda1"
:/usr/lib/nagios/plugins$
no output from the command!
what does this mean?

Re: problem with nrpe and ubuntu

PostPosted: Tue Jul 11, 2017 12:44 pm
by tgriep
The path in your command doesn't look right so try running this example using the full path to the plugin.
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sudo su nagios -c "/usr/lib/nagios/plugins/check_disk/check_disk -w 20% -c 10% -p /dev/sda1"


If an error is generated when you run it, post it here so we can view it.
One thing to check is to see if the nagios user account can access the folders the plugins are located in and that it can execute the plugins themselves.
The error you are receiving could be caused by that.

Re: problem with nrpe and ubuntu

PostPosted: Fri Jul 28, 2017 4:55 am
by majed
Peace, I was on a long sick leave.
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sudo su nagios -c "/usr/lib/nagios/plugins/check_disk/check_disk -w 20% -c 10% -p /dev/sda1"
:~$ cd /usr/lib/nagios/plugins/
:/usr/lib/nagios/plugins$ sudo  -s -u nagios ./check_nrpe -H 127.0.0.1 -c check_disk
DISK OK - free space: / 6770 MB (70% inode=82%);| /=2885MB;8156;9176;0;10196


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:~$ /usr/lib/nagios/plugins/check_disk  -w 20% -c 10% -p /dev/sda1
DISK OK - free space: / 6770 MB (70% inode=82%);| /=2885MB;8156;9176;0;10196
:~$ sudo -i -u nagios
:~$ /usr/lib/nagios/plugins/check_disk  -w 20% -c 10% -p /dev/sda1
DISK OK - free space: / 6770 MB (70% inode=82%);| /=2885MB;8156;9176;0;10196
:~$ sudo su nagios -c "/usr/lib/nagios/plugins/check_disk  -w 20% -c 10% -p /dev/sda1"
:~$

i tried su - nagios but it keeps saying the password is wrong, while sudo -i -u nagios did not ask for a password. is your suspicion correct?

Re: problem with nrpe and ubuntu

PostPosted: Fri Jul 28, 2017 12:58 pm
by tgriep
I think the issue is that the nagios useraccount has a password set to it or it is expired and that is causing the issue.
Login to that server as root and run the following to remove the password and to set the account to not expire.
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passwd --delete nagios
chage -I -1 -m 0 -M 99999 -E -1 nagios

The nagios user account cannot have a password so hopefully this will fix the issue.