How to Add Host in Zabbix Server to Monitor

Original post: http://tecadmin.net/add-host-zabbix-server-monitor/

After installing Zabbix Server and Zabbix Agent, lets move to add your first host in Zabbix monitoring. There are Zabbix is template rich tools, It contains lots of pre defined templates which we can easily used with our hosts.

There are two ways to add hosts in Zabbix:

1. Zabbix has capability to scan your network and automatically add all the hosts in Zabbix server.
2. Second method is used for adding hosts manually.

Using this tutorial, we are going to add host manually. Follow the below steps to add your first host which is running with Linux operating system.

Adding New Host in Zabbix

Firstly we need to login to zabbix web interface using admin account.

After login follow the steps given below, You may also refer screenshot showing just after these steps.

• Click on Configuration Menu
• Click on Hosts submenu
• Click on Create Host button at right side

Now fill the following details of remote host and go to Templates tab.

• Enter Hostname: Hostname of Remote system
• Visible name: Name to be display in zabbix
• Group: Select the desired group for you host
• Agent interface: Fill the info of Zabbix agent running on host
• Status: Select initial status

• Click on add link
• Select desired Template : Please select carefully, Because it will enabled all checks for the host
• Click on save button

Congratulation! You have added first host for zabbix monitoring. Repeat the same task for other hosts too.

How to View Graph in Zabbix

Graphs are always attracted the new users, Below screenshot will help you to how to view graphs in zabbix. If you have just added the host, you need to wait for few time, so that zabbix can collect some data from remote host to show on graph.

Thank You for using this article, if this tutorial helps please do forgot to share it with your friends.

Use below link to read more about zabbix configurationhttps://www.zabbix.com/documentation/2.0/manual/config

How to Install Zabbix Agent on CentOS/RHEL 7/6/5

Original post: http://tecadmin.net/install-zabbix-agent-on-centos-rhel/

Zabbix Agent is required to install on all remote systems needs to be monitor through Zabbix server. The Zabbix Agent collects resource utilization data and applications data on client system and provide such information to Zabbix server on there requests.

There are two types of checks between Zabbix Server and Client.
·         Passive Check : Zabbix Agent sent data to server on there request.
·         Active Check : Zabbix Agent sends data periodically to Server.

After installing zabbix server on your server, Now we are moving to install agent on remote system’s. This article will help you to install zabbix agent on CentOS/RHEL 7/6/5 systems. After completing this step go to next article add Host in Zabbix Server.

Installing Zabbix Agent
Follow the below instructions to install Zabbix Agent on CentOS, RHEL 7/6/5 systems.

Step 1: Add Required Repository

Before installing Zabbix Agent first configure zabbix yum repository using following commands as per your required version and operating system.

CentOS/RHEL 7:

# rpm -Uvh http://repo.zabbix.com/zabbix/2.2/rhel/7/x86_64/zabbix-release-2.2-1.el7.noarch.rpm

CentOS/RHEL 6:
# rpm -Uvh http://repo.zabbix.com/zabbix/2.2/rhel/6/x86_64/zabbix-release-2.2-1.el6.noarch.rpm

CentOS/RHEL 5:
# rpm -Uvh http://repo.zabbix.com/zabbix/2.2/rhel/5/x86_64/zabbix-release-2.2-1.el5.noarch.rpm

Step 2: Install Zabbix Agent

After installing yum repository packages in our system. Now use following command to install Zabbix agent on your Linux sytem.

# yum install zabbix zabbix-agent nano –y

Step 3: Update Zabbix Agent Configuration

As zabbix agent has been successfully installed on our remote system. Now we just need to configure zabbix agent by adding zabbix server ip in its configuration file /etc/zabbix/zabbix_agentd.conf

sed -i 's/Server=127.0.0.1/ Server=192.168.1.11/g' /etc/zabbix/zabbix_agentd.conf

Or

nano /etc/zabbix/zabbix_agentd.conf

#Server=[zabbix server ip]
#Hostname=[ Hostname of client system ]

Server=192.168.1.11
Hostname=Server1

Step 4: Restarting Zabbix Agent

After adding zabbix server ip in configuration file, now restart agent service using below command.

service zabbix-agent stop
service zabbix-agent start

To start and stop zabbix-agent service anytime use following commands.

# service zabbix-agent start
# service zabbix-agent stop

Step 5: Add to autostart 

chkconfig zabbix-agent on

Step 6: Add to firewall

firewall-cmd --permanent --zone=public --add-port=10050/tcp
firewall-cmd --permanent --zone=public --add-port=10050/udp
firewall-cmd --reload

Install Sails js Centos

1. Install nodejs and npm
2 Update npm
3 install sails
4. add nginx config for sails : (http://blog.saitov.me/2015/02/configure-sailsjs-expressjs-to-run-with.html)

yum install -y nodejs nmp

npm install -g npm

npm install -g sails grunt grunt-cli pm2 jade 

Install steps Centos 7

Have to do:

yum install epel-release -y
cd /
yum install -y wget mc sshpass unzip nano git
yum update -y

2  Disable Selinux:
sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config
setenforce Permissive

3. Change ssh port: http://blog.saitov.me/2015/03/centos-7-rhel-7-change-openssh-port.html


Optional:
nginx: http://blog.saitov.me/2015/02/install-nginx-on-centos-7.html
yii: http://blog.saitov.me/search/label/YII
Sails js: http://blog.saitov.me/search/label/sails

Add. repositories:

cd /tmp && wget http://rpms.famillecollet.com/enterprise/remi-release-7.rpm
sudo rpm -Uvh remi-release-7*.rpm
cd /tmp && wget http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el7.rf.x86_64.rpm
sudo rpm -Uvh rpmforge-release-0.5.3-1.el7.rf.x86_64.rpm

EMFILE, Too many open files - Set ulimit parameters

I have a problem - got error for Sails js

EMFILE, Too many open files 

By default the number of open files  pro user in Centos  is 1024. In my case this number was  too small so I have to increase it.This is done with the  ulimit command:

$ulimit -a   # see all the kernel parameters
$ulimit -n   #see the number of open files
$ulimit -n 9000  #  set the number open files to 9000

The problem with this way is that the ulimit parameter is only set currently  for this command terminal and user.If you open a new tab and type again ulimit -a you will see that the number of open files is 1024.This means that after a reboot you’ll need to set the parameter again.

1.  First, in order to set this options automatically  you have to edit the etc/security/limits.conf file.

$sudo gedit /etc/security/limits.conf    #open the file in gedit

The # means that this part is commented.The wildcard * means  for all users.We need to set the nofile option meaning maximum number of open files.If you want to change the number of files of user, you should add this line in the limits.conf:

user  soft  nofile 9000

user  hard  nofile 65536

If  you want to set the nofile only for superuser you just write root instead of user.

root soft  nofile 9000

root hard  nofile 65536

2. Second step: 

Added to /etc/sysctl.conf:
fs.file-max = 65536

Then re-read the sysctl.conf:
/sbin/sysctl -p

Tools I liked

1.  TCP Port Scan with Nmap  - scan ports, port ranges, ...
2. JSON Viewer - simple and do all u need (Other one )
3. HTML Formatter - good one
4. YUI Compressor Online JavaScript/CSS - well known YUI Compressor online
5. https://temp-mail.org  /  10minutemail.com - super mail for one time registration / entrance
6. JsConsole.com - remote js console window
7. diawi.com - great a tool for iOS developers to deploy Development and Ad hoc iOS applications directly to the device
8. Javascript jsbeautifier  - Online fomatter Javascript / HTML
9. XShell  - super ssh / telnet /sftp client
10. ICO creator online - png to ico convertor
11. HTML 2 Jade  - onlne convertor
12. Jade 2 HTML - onlne convertor
13. Icons / Glyphs generator - webhostinghub.com/glyphs/
14. Clink  Linux like Windows Cmd
15. GoAccess - real-time web log analyzer (IIS, nginx, etc)
16. XnView Image Viewer - my preferred
17. Get UDID of IPHONE
18. ConEmu -   Super console for Windows, with full screen, Linux-like goods
19. Image to css data uri (embedded image ) - A simple utility to convert an image into base 64 data URIs for embedding images.
20. nvm-windows - node.js version management
21. WinCDEmu - CD/DVD/BD emulator Open source
22. cmder.net - Super console for Windows -  ConEmu + Clink

CentOS 7 / RHEL 7 : change OpenSSH port number ( SELINUX enabled )

Original post: http://sharadchhetri.com/2014/10/15/centos-7-rhel-7-change-openssh-port-number-selinux-enabled/

CentOS 7 / RHEL 7 : change OpenSSH port number ( SELINUX enabled )

The tutorial will explain about how to change default ssh port number in OpenSSH Server on CentOS 7 and RHEL 7 . We will change the SSH default port no. 22 to our desired number and we will keep SELINUX enabled. We will also add new firewalld rule with respect to new ssh port number.

Generally for security point of view , we change the default ssh port number 22 to any other port number. Always be careful while selecting new port number. We should select the number above the “well known port number” that is above port number 1024 . Also we should not use same application /Utility specific default port number, for example just as we use in tomcat port 8080, MySQL 3306. In simple words, select the port number above 1024 as well as should not conflict with any application/utility/program etc.

Change SSH port number

First take the backup of sshd_config file.And then go for edit.

cp -p /etc/ssh/sshd_config /etc/ssh/sshd_config.orig.$(date +%F)

Now edit the file /etc/ssh/sshd_config. Search for line #Port 22 or Port 22 .
Note: The # is used for commenting the line. But because ssh has well known port number 22 (below 1024). It will by default listen on port number 22.

Remove # from line Port 22. And the change 22 to new port number, here we have selected 2292 .

sed -i 's/#Port 22/Port 27628/g' /etc/ssh/sshd_config

Or

vi /etc/ssh/sshd_config

Port 2292

SELINUX for SSH

By default SELINUX only allow port no. 22 for ssh. Now add new port context 2292.
Note: Replace 2292 in case you have selected different port number

semanage port -a -t ssh_port_t -p tcp 2292

Now check once the port context for ssh

semanage port -l | grep ssh

Below given is output from our server

[root@localhost ~]# semanage port -l | grep ssh
ssh_port_t                     tcp      2292, 22
[root@localhost ~]#

Now Restart the SSH service

systemctl restart sshd.service

Allow port 2292 with firewalld

Now allow port number 2292 for ssh. Run the below given command. It will permanently add the new firewalld rule in public zone for port 2292 with TCP protocol.

firewall-cmd --permanent --zone=public --add-port=2292/tcp

Reload firewalld

firewall-cmd --reload

Check listening ssh port with ss command

With ss command, you can find the listening port for ssh. Use below command for this

ss -tnlp|grep ssh

Below given output is reference from our server

[root@localhost ~]# ss -tnlp|grep ssh
LISTEN     0      128                       *:2292                     *:*      users:(("sshd",2786,3))
LISTEN     0      128                      :::2292                    :::*      users:(("sshd",2786,4))
[root@localhost ~]#

Try to do ssh access to server by using port no. 2292 from remote client.

ssh -p 2292 root@192.168.56.101

* Change 192.168.56.101 with your server ip address.
* Change 2292 with your new ssh port number as you set while reading this post.
* Change root with user name which is allowed to get ssh access in your server.

If all works from remote - remove 22 port from firewall

firewall-cmd --permanent --zone=public --remove-port=22/tcp
firewall-cmd --reload