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Server

Monitoring Linux Servers behind squid proxy via Nagioscore

muhib

4/4/23, 7:21 AM

This is my first post here, please help me.

I want to monitor a few redhat servers which are behind a squid proxy server. I have done the below configuration:

RedHat Node behind proxy server configuration:- I have installed nrpe and also copied check_disk, check_cpu and check_mem plugins under /usr/lib64/nagios/plugins.

I also added the below lines in /etc/nagios/nrpe.cfg file.

allowed_hosts=127.0.0.1,Squid_Proxy_server_IP
command[check_disk]=/usr/lib64/nagios/plugins/check_disk -w $ARG1$ -c $ARG2$ -p $ARG3$
command[check_cpu]=/usr/lib64/nagios/plugins/check_cpu -w $ARG1$ -c $ARG2$
command[check_mem]=/usr/lib64/nagios/plugins/check_mem -w $ARG1$ -c $ARG2$ -W $ARG3$ -C $ARG4$

Squid Proxy Server Configuration:- I have also installed nrpe in squid proxy server and copied check_disk, check_cpu, check_mem, check_nrpe and check_ping plugins under /usr/lib64/nagios/plugins. I also added the below lines in /etc/nagios/nrpe.cfg file.

allowed_hosts=127.0.0.1,Nagios_server_IP
command[check_disk]=/usr/lib64/nagios/plugins/check_disk -w $ARG1$ -c $ARG2$ -p $ARG3$
command[check_cpu]=/usr/lib64/nagios/plugins/check_cpu -w $ARG1$ -c $ARG2$
command[check_mem]=/usr/lib64/nagios/plugins/check_mem -w $ARG1$ -c $ARG2$ -W $ARG3$ -C $ARG4$
command[check_proxy]=/usr/lib64/nagios/plugins/check_nrpe -t 60 -H $ARG1$ -c $ARG2$ -a $ARG3$ $ARG4$
command[check_ping]=/usr/lib64/nagios/plugins/check_ping -H $ARG1$ -w 3000.0,80% -c 5000.0,100% -p 5

If I run the below command from squid proxy server to RedHat server, I can get a correct output.

/usr/local/nagios/libexec/check_nrpe -H RedHat_IP -c check_disk -a 20% 10% /app

Also If I run the below command from nagios server to squid proxy server, I can get a correct output.

/usr/local/nagios/libexec/check_nrpe -H Proxy_server_IP -c check_disk -a 20% 10% /app

But if I run the below command to check the RedHat server status directly from nagios server via Proxy server I get "Error: Unable to read the output".

./check_nrpe -H Proxy_node_IP -c check_proxy -a RedHat_IP_behind_Proxy check_disk "20% 10% /app"

Please help me as it has become quite critical for our environment.

0 + 0

nagios

Tero Kilkanen

4/4/23, 7:58 AM

I don't know details of Nagios, but I doubt that it uses HTTP(S) compatible protocol with its remote communication. Squid is an HTTP(S) proxy, which uses HTTP(S). You should look into SSH tunneling for this use case.

pzkpfw

4/7/23, 1:42 PM

You should try running `check_nrpe -H Proxy_node_IP (localhost) -c check_proxy -a RedHat_IP_behind_Proxy check_disk "20% 10% /app"` from the *squid* server, and not the nagios server. Hopefully you'll get some more useful feedback on what's failing instead of the generic "unable to read output".

wrieedx

4/13/23, 7:06 AM

NRPE uses TCP port 5666. I doubt you will not be able proxy NRPE through Squid. Is allowing port 5666 through your firewall out of the question?

Score:0

Server

Alexander Pavluchenko

4/4/23, 8:13 AM

do you have issue if check_by_ssh from Nagios?

Squid should be prepared:

acl localnet src X.X.X.X/X

Next, add the SSH port as a safe port by adding the following line:

acl Safe_ports port 22

0 + 0

muhib

4/4/23, 9:07 AM

Thanks for the reply... I am using nrpe because SSH is not allowed in our environment. i am also not the owner of squid proxy server. I will discuss your suggested approach with my teamate. Should I add port 5666 as a safe port in squid proxy configuration?.

digijay

4/4/23, 11:00 AM

Adding 5666 as a safe port would definitly be worth a try.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Monitoring Linux Servers behind squid proxy via Nagioscore

TH: ตรวจสอบเซิร์ฟเวอร์ Linux ที่อยู่เบื้องหลัง Squid Proxy ผ่าน Nagioscore

RO: Monitorizarea serverelor Linux din spatele proxy squid prin Nagioscore

RU: Мониторинг серверов Linux за прокси-сервером squid через Nagioscore

VI: Giám sát Máy chủ Linux đằng sau proxy mực qua Nagioscore

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