How to Install and Setup Munin on CentOS 7

Munin on CentOS 7

Munin is open source and free software for monitoring computer system, network monitoring and application infrastructure monitoring software. Munin offers monitoring and alerting for servers, switches, applications, and services.

Munin can help system administrators to analyze the trend of the computer system whether it is experiencing problems or not. It can be an easier alternative to the popular open-source software zabbix monitoring.

In this article, I will explain how you can monitor your linux CentOS with Munin and the simple steps to install and setup Munin on CentOS 7.

Steps to Install and Setup Munin on CentOS 7

1. Enable or install the EPEL Repository into CentOS 7. Read more on how to Enable EPEL Repository on CentOS 7 / RHEL 7

2. Munin requires a web server to run. In this article, we will use apache. Install apache, Munin and Munin Node with yum command :

# yum install httpd munin munin-node -y

3. Start and enable apache and munin at boot.

# systemctl start httpd
# systemctl enable httpd
# systemctl start munin-node
# systemctl enable munin-node

4. We want munin to use the name centos72.ehowstuff.local instead of localhost. Please open edit the setting in /etc/munin/munin.conf

# vim /etc/munin/munin.conf

Original :

[localhost]
    address 127.0.0.1
    use_node_name yes

Change to :

[centos72.ehowstuff.local]
    address 127.0.0.1
    use_node_name yes

5. You also have optional to change the munin node hostname :

# vim /etc/munin/munin-node.conf

Original :

host_name localhost.localdomain

Change to :

host_name centos72.ehowstuff.local

6. Next go to the Apache virtual host configuration file to add the permission to access your network.

# vim /etc/httpd/conf.d/munin.conf

Add network segment that you allow to access to the CentOS server.

AuthUserFile /etc/munin/munin-htpasswd
AuthName "Munin"
AuthType Basic
require valid-user

Order Deny,Allow
Deny from all
Allow from 127.0.0.1 192.168.0.0/24
..
..

7. Munin statistics page shall be protected by a username and password. We can add the new user (admin) and password to /etc/munin/munin-htpasswd with htpasswd command line. So we have to setup basic Apache authentication before we can start access the munin statistic page.

# htpasswd /etc/munin/munin-htpasswd admin
New password:
Re-type new password:
Adding password for user admin

8. Allow port 80 in the firewalld permanently. learn more how to configure Firewalld on CentOS 7.

a) Get default zone :

# firewall-cmd --get-active-zones
public
  interfaces: ens160

b) Allow port 80 permanently in firewalld :

# firewall-cmd --permanent --zone=public --add-port=80/tcp
success

c) reload the setting to take effect immediately :

# firewall-cmd --reload
success

d) List all active firewalld configuration :

# firewall-cmd --list-all
public (default, active)
  interfaces: ens160
  sources:
  services: dhcpv6-client ssh
  ports: 80/tcp
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:

9. Try access munin statistic page from client.

http://192.168.0.14/munin

Munin on CentOS 7

How to Setup nmon – Monitor Linux Performance

Nmon (Nigel’s Monitor) is a great performance monitoring tool for Linux operating system.

It was written initially for AIX to monitor system performance. nmon for Linux can be used to collect informations on CPU, memory, network, disk I/O, top processes etc.

System administrator can use nmon as a tuner or benchmark tool that will provide performance information in one go.

It can output the data on the screen or can be save the data into a comma separated file for analysis and longer term data capture.

Steps to setup nmon on linux operating system.

1. How to Add the RPMforge Repository on CentOS 6/RHEL 6 Linux Server

2. Rum yum command to install nmon :

# yum install nmon -y

3. Example of nmon command usage :

Type command :

# nmon

Sample output :
setup nmon

nmon keyboard shortcuts

q – To stop and exit nmon.
h – To see quick help (hint) screen and press h again to remove the hints.
Use the following command to turn on or off stats:
c – See cpu stats.
m – See memory stats.
d – See disk stats.
k – See kernel stats.
n – See network stats.
N – See NFS stats.
j – See file system stats.
t – See top process.
V – See virtual memory stats.
. – See only busy disks/procs.
v – Verbose mode (display as Ok/warning/danger on screen).

Sample outputs :
setup nmon

4. If you prefer to run nmon as a daemon in the background, run the below command, nmon will complete the data file collection and it will save in a file *.nmon file such as oss_140817_2359.nmon with the details of the command as below :

# nmon -f -s2 -c 30
-f : Start data collect mode and output in spreadsheet format.
-s 2 : Wait between 2 seconds or capture data every 2 seconds.
-c30 : Total number of refreshes (30).

4 Top Command Howto on Linux RHEL 6/CentOS 6

In this article, i will help you to explore most frequently used top commands that linux system administrator use when analyzing the linux performance and use for daily system administrative jobs. Top command displays system summary information such as tasks currently being managed by the Linux kernel, displays ongoing look at processor activity in real time and will displays a listing of the most CPU-intensive tasks on the system. It also will show the processor and memory are being used and other information like running processes. It will help you to summarize how much of your system’s resources are taking up.

1. How to display top command result :

[root@rhel6 ~]# top

top
This command will show information like tasks, memory, cpu load average, swap and number of users. Press ‘q’ to quit window.

2. How to display selected user using top -u :

[root@rhel6 ~]# top -u apache

top

3. How to display specific process with given PIDs Using top -p(e.g PID 2449, 2450) :

[root@rhel6 ~]# top -p 2449,2450

top

4. How to quit top command after a specified number of iterations :

[root@rhel6 ~]# top -n 10

This top command will automatically exit after 10 number of repetition.