#!/bin/bash

## Windows
# Command to run for PSK ID and PSK with powershell
# PSK ID: (1..16 | %{ '{0:x}' -f (Get-Random -Max 16) }) -join ''
# PSK: (1..64 | %{ '{0:x}' -f (Get-Random -Max 16) }) -join ''


# installs the zabbix agent and configures it

# make sure we are running as sudo
if [ "$EUID" -ne 0 ]; then
  echo "Please run as root"
  exit
fi

# get OS ditro and version
OS=$(lsb_release -si)
OS_VER=$(lsb_release -sr)

# zabbix server
ZABBIX_SERVER="gauntzabbix.home.johnhgaunt.com"

if [ ${OS} == 'Debian' ]; then
	# Install the repository configuration package. This package contains apt (software package manager) configuration files.
	if [[ ${OS_VER} =~ ^9.* ]]; then
      wget -P /tmp/ https://repo.zabbix.com/zabbix/4.0/debian/pool/main/z/zabbix-release/zabbix-release_4.0-3+stretch_all.deb
      dpkg -i /tmp/zabbix-release_4.0-3+stretch_all.deb
    elif [[ ${OS_VER} =~ ^10.* ]]; then
    	wget -P /tmp/ https://repo.zabbix.com/zabbix/4.0/debian/pool/main/z/zabbix-release/zabbix-release_4.0-3+buster_all.deb
        dpkg -i /tmp/zabbix-release_4.0-3+buster_all.deb
    fi
    # update the cache
    apt update
    # install the agent
    apt install -y zabbix-agent
    
elif [ ${OS} == 'Ubuntu' ]; then
	# Install the repository configuration package. This package contains apt (software package manager) configuration files.
	if [[ ${OS_VER} == 16.04 ]]; then
      wget -P /tmp/ https://repo.zabbix.com/zabbix/4.0/ubuntu/pool/main/z/zabbix-release/zabbix-release_4.0-3+xenial_all.deb
      dpkg -i /tmp/zabbix-release_4.0-3+xenial_all.deb
    elif [[ ${OS_VER} == 18.04 ]]; then
    	wget -P /tmp/ https://repo.zabbix.com/zabbix/4.0/ubuntu/pool/main/z/zabbix-release/zabbix-release_4.0-3+bionic_all.deb
        dpkg -i /tmp/zabbix-release_4.0-3+bionic_all.deb
    fi
    # update the cache
    apt update
    # install the agent
    apt install -y zabbix-agent
    
elif [ ${OS} == 'CentOS' ]; then
    # Install the repository configuration package. This package contains yum (software package manager) configuration files.
   	if [[ ${OS_VER} =~ ^7.* ]]; then 
   		rpm -Uvh https://repo.zabbix.com/zabbix/4.0/rhel/7/x86_64/zabbix-release-4.0-2.el7.noarch.rpm
    fi
    # install the zabbix agent
    yum install -y zabbix-agent
    cat << EOF >> /etc/firewalld/services/zabbix-agent.xml
<?xml version="1.0" encoding="utf-8"?>
    <service>
        <short>zabbix agent</short>
        <description>zabbix agent</description>
        <port protocol="tcp" port="10050"/>
        <port protocol="udp" port="10050"/>
    </service>
EOF
    sleep 5
    firewall-cmd --add-service=zabbix-agent --permanent
    firewall-cmd --reload
    
else
    echo "You are running an unsupported OS"
    echo "Support OSes: Debian 9/10, Ubunut 16.04/18.04, CentOS 7"
    echo "Your OS: ${OS} ${OS_VER}"
    exit
fi



# ask for the hostname
read -e -p "Enter Hostname: " -i "$(cat /etc/hostname)" hostname

# configure the hostname
sed --in-place 's/^Hostname=Zabbix\ server/Hostname='${hostname}'/' /etc/zabbix/zabbix_agentd.conf
# configure the zabbix server
sed --in-place 's/^Server=127.0.0.1/Server='${ZABBIX_SERVER}'/' /etc/zabbix/zabbix_agentd.conf
# configure the zabbix server
sed --in-place 's/^ServerActive=127.0.0.1/ServerActive='${ZABBIX_SERVER}'/' /etc/zabbix/zabbix_agentd.conf
# configure the encryption, cheeck before running this as it adds lines to keep comments
if [ $(grep -c TLSAccept=psk /etc/zabbix/zabbix_agentd.conf) -eq 0 ]; then
  sed --in-place $'s/^# TLSAccept=unencrypted/# TLSAccept=unencrypted\\\nTLSAccept=psk/' /etc/zabbix/zabbix_agentd.conf
  sed --in-place $'s/^# TLSConnect=unencrypted/# TLSConnect=unencrypted\\\nTLSConnect=psk/' /etc/zabbix/zabbix_agentd.conf
  # generate random PSK ID
  PSKID=$(openssl rand -hex 8)
  sed --in-place $'s/^# TLSPSKIdentity=/# TLSPSKIdentity=\\\nTLSPSKIdentity='${PSKID}'/' /etc/zabbix/zabbix_agentd.conf
  # generate psk
  TLSPSK=$(openssl rand -hex 32 | tee /etc/zabbix/zabbix_agentd.psk)
  sed --in-place $'s/^# TLSPSKFile=/# TLSPSKFile=\\\nTLSPSKFile=\/etc\/zabbix\/zabbix_agentd.psk/' /etc/zabbix/zabbix_agentd.conf

  echo "############################################################"
  echo "##                 Encryption Details                     ##"
  echo "## Please enter the PSK ID and PSK into the Zabbix Server ##"
  echo "############################################################"
  echo "PSK Identity = ${PSKID}"
  echo "PSK = ${TLSPSK}"

fi

systemctl restart zabbix-agent 

systemctl enable zabbix-agent