Link to install zabbix server on centOS 6- http://www.unixmen.com/install-zabbix-monitoring-tool-centos-6-5/

Zabbix Documentation – https://www.zabbix.com/documentation/3.4/manual/installation/install_from_packages/rhel_centos

Install on CentOS 7 – http://www.unixmen.com/how-to-install-zabbix-server-on-centos-7/

Install Epel

# yum install epel-release

Configure the ZabbixZone package repository and GPG key using command:

# rpm --import http://repo.zabbix.com/RPM-GPG-KEY-ZABBIX

# rpm -Uv  http://repo.zabbix.com/zabbix/2.4/rhel/7/x86_64/zabbix-release-2.4-1.el7.noarch.rpm

Install the agent

# yum install zabbix-agent

Modify Zabbix Agent Configuration
Open zabbix_agentd.conf and make below necessary changes (Add your Zabbix Server IP and add Zabbix Agent hostname) and save + Exit.

# sudo nano /etc/zabbix/zabbix_agentd.conf
Server=192.168.1.106
ServerActive=192.168.1.106
Hostname=server.geekdecoder.com

Set to on

# chkconfig zabbix-agent on

Restart Zabbix Agent

# service zabbix-agent restart
or
# /etc/init.d/zabbix-agent restart

# For Systemd Systeme #
# systemctl restart zabbix-agent.service
or
# systemctl restart zabbix-agent
or
# /bin/systemctl restart zabbix-agent.service

Add firewall rule in CentOS 7:

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