For Debian 8:

$ wget http://repo.zabbix.com/zabbix/3.0/debian/pool/main/z/zabbix-release/zabbix-release_3.0-1+jessie_all.deb

$ dpkg -i zabbix-release_3.0-1+jessie_all.deb

$ apt update

# apt  install zabbix-agent
# vi /etc/zabbix/zabbix_agentd.conf

#Server=[zabbix server ip]

#Hostname=[Hostname of client system ]

[line 95]  Server=192.168.1.11

[line 147 ]Hostname=Server2

[Line 236] Timeout=30 (and remove the #, have changed because of the "Zabbix agent on Host.name is unreachable for 5 minutes" ) 

/etc/init.d/zabbix-agent restart