From f103339165b0adcfd969545d76662120ee5f81d5 Mon Sep 17 00:00:00 2001
From: xiagw <fxiaxiaoyu@gmail.com>
Date: Fri, 5 Jan 2018 15:15:01 +0800
Subject: [PATCH] function for all .

---
 openvpn-install.sh | 1041 ++++++++++++++++++++++----------------------
 1 file changed, 525 insertions(+), 516 deletions(-)

diff --git a/openvpn-install.sh b/openvpn-install.sh
index ed7d55e..04d9729 100644
--- a/openvpn-install.sh
+++ b/openvpn-install.sh
@@ -30,58 +30,21 @@ file_client_tpl="${dir_openvpn}/client-template.txt"
 file_openvpn_conf="${dir_openvpn}/server.conf"
 file_iptables='/etc/iptables/iptables.rules'
 
-## function determine the operating system version
-detect_os_ver(){
-
-if [[ -e /etc/debian_version ]]; then
-	OS="debian"
-	# Getting the version number, to verify that a recent version of OpenVPN is available
-	VERSION_ID=$(cat /etc/os-release | grep "VERSION_ID")
-	SYSCTL='/etc/sysctl.conf'
-	if [[ "$VERSION_ID" != 'VERSION_ID="7"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="8"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="9"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="12.04"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="14.04"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="16.04"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="16.10"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="17.04"' ]]; then
-		echo 'Your version of Debian/Ubuntu is not supported.'
-		echo "I can't install a recent version of OpenVPN on your system."
-		echo ''
-		echo "However, if you're using Debian unstable/testing, or Ubuntu beta,"
-		echo 'then you can continue, a recent version of OpenVPN is available on these.'
-		echo 'Keep in mind they are not supported, though.'
-		while [[ "$CONTINUE" != [yn]  ]]; do
-			read -p 'Continue ? [y/n]: ' -e CONTINUE
-		done
-		if [[ 'n' = "$CONTINUE" ]]; then
-			echo 'Ok, bye !'
-			exit 4
-		fi
-	fi
-elif [[ -e /etc/centos-release || -e /etc/redhat-release && ! -e /etc/fedora-release ]]; then
-	OS='centos'
-	SYSCTL='/etc/sysctl.conf'
-elif [[ -e /etc/arch-release ]]; then
-	OS='arch'
-	SYSCTL='/etc/sysctl.d/openvpn.conf'
-elif [[ -e /etc/fedora-release ]]; then
-	OS='fedora'
-	SYSCTL='/etc/sysctl.d/openvpn.conf'
-else
-	echo "Looks like you aren't running this installer on a Debian, Ubuntu, CentOS or ArchLinux system"
-	exit 4
-fi
-}
-
 
 install_easyrsa(){
-	# An old version of easy-rsa was available by default in some openvpn packages
-	if [[ -d ${dir_easy}/ ]]; then
-		rm -rf ${dir_easy}/
-	fi
-	# Get easy-rsa
-	url_easy='https://github.com/OpenVPN/easy-rsa/releases/download/v3.0.3/EasyRSA-3.0.3.tgz'
-	file_easy=${url_easy##*/}
-	wget -O ~/${file_easy} ${url_easy}
-	tar xzf ~/${file_easy} -C ~/
-	mv ~/${file_easy%.tgz} ${dir_easy}
-	chown -R root:root ${dir_easy}/
-	rm -rf ~/${file_easy}
+
+# An old version of easy-rsa was available by default in some openvpn packages
+if [[ -d ${dir_easy}/ ]]; then
+	rm -rf ${dir_easy}/
+fi
+# Get easy-rsa
+url_easy='https://github.com/OpenVPN/easy-rsa/releases/download/v3.0.3/EasyRSA-3.0.3.tgz'
+file_easy=${url_easy##*/}
+wget -O ~/${file_easy} ${url_easy}
+tar xzf ~/${file_easy} -C ~/
+mv ~/${file_easy%.tgz} ${dir_easy}
+chown -R root:root ${dir_easy}/
+rm -rf ~/${file_easy}
 }
 
 set_firewall(){
@@ -134,37 +97,39 @@ set_firewall(){
 	fi
 }
 
-newclient () {
-	# Where to write the custom client.ovpn?
-	if [ -e /home/$1 ]; then  # if $1 is a user name
-		homeDir="/home/$1"
-	elif [ ${SUDO_USER} ]; then   # if not, use SUDO_USER
-		homeDir="/home/${SUDO_USER}"
-	else  # if not SUDO_USER, use /root
-		homeDir="${dir_openvpn}"
-	fi
-	# Generates the custom client.ovpn
-	file_client="$homeDir/$1.ovpn"
-	cp ${file_client_tpl} ${file_client}
-	echo "<ca>" >> ${file_client}
-	cat ${dir_easy}/pki/ca.crt >> ${file_client}
-	echo "</ca>" >> ${file_client}
-	echo "<cert>" >> ${file_client}
-	cat ${dir_easy}/pki/issued/$1.crt >> ${file_client}
-	echo "</cert>" >> ${file_client}
-	echo "<key>" >> ${file_client}
-	cat ${dir_easy}/pki/private/$1.key >> ${file_client}
-	echo "</key>" >> ${file_client}
-	echo "key-direction 1" >> ${file_client}
-	echo "<tls-auth>" >> ${file_client}
-	cat ${dir_openvpn}/tls-auth.key >> ${file_client}
-	echo "</tls-auth>" >> ${file_client}
+generate_newclient() {
+
+# Where to write the custom client.ovpn?
+if [ -e /home/$1 ]; then  # if $1 is a user name
+	homeDir="/home/$1"
+elif [ ${SUDO_USER} ]; then   # if not, use SUDO_USER
+	homeDir="/home/${SUDO_USER}"
+else  # if not SUDO_USER, use /root
+	homeDir="${dir_openvpn}"
+fi
+# Generates the custom client.ovpn
+file_client="$homeDir/$1.ovpn"
+cp ${file_client_tpl} ${file_client}
+echo "<ca>" >> ${file_client}
+cat ${dir_easy}/pki/ca.crt >> ${file_client}
+echo "</ca>" >> ${file_client}
+echo "<cert>" >> ${file_client}
+cat ${dir_easy}/pki/issued/$1.crt >> ${file_client}
+echo "</cert>" >> ${file_client}
+echo "<key>" >> ${file_client}
+cat ${dir_easy}/pki/private/$1.key >> ${file_client}
+echo "</key>" >> ${file_client}
+echo "key-direction 1" >> ${file_client}
+echo "<tls-auth>" >> ${file_client}
+cat ${dir_openvpn}/tls-auth.key >> ${file_client}
+echo "</tls-auth>" >> ${file_client}
 }
 
 
 ## function for install openvpn server
 install_openvpn(){
-	clear
+
+clear
 cat <<EOF
 Welcome to the secure OpenVPN installer (github.com/Angristan/OpenVPN-install)
 
@@ -175,18 +140,19 @@ I need to know the IPv4 address of the network interface you want OpenVPN listen
 If your server is running behind a NAT, (e.g. LowEndSpirit, Scaleway) leave the IP address as it is. (local/private IP)
 Otherwise, it should be your public IPv4 address.
 EOF
-	read -p "IP address: " -e -i $IP IP
-	
-	echo ""
-	echo "What port do you want for OpenVPN?"
-	read -p "Port: " -e -i 1194 PORT
-	
-	echo ""
-	echo "1/6.What protocol do you want for OpenVPN?"
-	echo "Unless UDP is blocked, you should not use TCP (unnecessarily slower)"
-	while [[ $PROTOCOL != "udp" && $PROTOCOL != "tcp" ]]; do
-		read -p "Protocol [udp/tcp]: " -e -i udp PROTOCOL
-	done
+read -p "IP address: " -e -i $IP IP
+
+echo ""
+echo "What port do you want for OpenVPN?"
+read -p "Port: " -e -i 1194 PORT
+
+echo ""
+echo "1/6.What protocol do you want for OpenVPN?"
+echo "Unless UDP is blocked, you should not use TCP (unnecessarily slower)"
+while [[ $PROTOCOL != "udp" && $PROTOCOL != "tcp" ]]; do
+	read -p "Protocol [udp/tcp]: " -e -i udp PROTOCOL
+done
+
 cat <<EOF
 2/6.What DNS do you want to use with the VPN?
    1) Current system resolvers (from /etc/resolv.conf)
@@ -198,9 +164,10 @@ cat <<EOF
    7) Yandex Basic (Russia)
    8) AdGuard DNS (Russia)
 EOF
-	while [[ $DNS != [1-8] ]]; do
-		read -p "DNS [1-8]: " -e -i 1 DNS
-	done
+while [[ $DNS != [1-8] ]]; do
+	read -p "DNS [1-8]: " -e -i 1 DNS
+done
+
 cat <<EOF
 See https://github.com/Angristan/OpenVPN-install#encryption to learn more about 
 the encryption in OpenVPN and the choices I made in this script.
@@ -218,232 +185,237 @@ They are relatively slower but as secure as AES.
    6) CAMELLIA-256-CBC
    7) SEED-CBC
 EOF
-	while [[ $CIPHER != [1-7] ]]; do
-		read -p "Cipher [1-7]: " -e -i 1 CIPHER
-	done
-	case $CIPHER in
-		1)
-		CIPHER="cipher AES-128-CBC"
-		;;
-		2)
-		CIPHER="cipher AES-192-CBC"
-		;;
-		3)
-		CIPHER="cipher AES-256-CBC"
-		;;
-		4)
-		CIPHER="cipher CAMELLIA-128-CBC"
-		;;
-		5)
-		CIPHER="cipher CAMELLIA-192-CBC"
-		;;
-		6)
-		CIPHER="cipher CAMELLIA-256-CBC"
-		;;
-		7)
-		CIPHER="cipher SEED-CBC"
-		;;
-	esac
-	echo ""
-	echo "4/6.Choose what size of Diffie-Hellman key you want to use:"
-	echo "   1) 2048 bits (fastest)"
-	echo "   2) 3072 bits (recommended, best compromise)"
-	echo "   3) 4096 bits (most secure)"
-	while [[ $DH_KEY_SIZE != [1-3] ]]; do
-		read -p "DH key size [1-3]: " -e -i 2 DH_KEY_SIZE
-	done
-	case $DH_KEY_SIZE in
-		1)
-		DH_KEY_SIZE="2048"
-		;;
-		2)
-		DH_KEY_SIZE="3072"
-		;;
-		3)
-		DH_KEY_SIZE="4096"
-		;;
-	esac
-	echo ""
-	echo "5/6.Choose what size of RSA key you want to use:"
-	echo "   1) 2048 bits (fastest)"
-	echo "   2) 3072 bits (recommended, best compromise)"
-	echo "   3) 4096 bits (most secure)"
-	while [[ $RSA_KEY_SIZE != [1-3] ]]; do
-		read -p "RSA key size [1-3]: " -e -i 2 RSA_KEY_SIZE
-	done
-	case $RSA_KEY_SIZE in
-		1)
-		RSA_KEY_SIZE="2048"
-		;;
-		2)
-		RSA_KEY_SIZE="3072"
-		;;
-		3)
-		RSA_KEY_SIZE="4096"
-		;;
-	esac
-	echo ""
-	echo "6/6.Finally, tell me a name for the client certificate and configuration"
-	while [[ $CLIENT = "" ]]; do
-		echo "Please, use one word only, no special characters"
-		read -p "Client name: " -e -i client CLIENT
-	done
-	echo ""
-	echo "Okay, that was all I needed. We are ready to setup your OpenVPN server now"
-	read -n1 -r -p "Press any key to continue..."
+while [[ $CIPHER != [1-7] ]]; do
+	read -p "Cipher [1-7]: " -e -i 1 CIPHER
+done
+case $CIPHER in
+	1)
+	CIPHER="cipher AES-128-CBC"
+	;;
+	2)
+	CIPHER="cipher AES-192-CBC"
+	;;
+	3)
+	CIPHER="cipher AES-256-CBC"
+	;;
+	4)
+	CIPHER="cipher CAMELLIA-128-CBC"
+	;;
+	5)
+	CIPHER="cipher CAMELLIA-192-CBC"
+	;;
+	6)
+	CIPHER="cipher CAMELLIA-256-CBC"
+	;;
+	7)
+	CIPHER="cipher SEED-CBC"
+	;;
+esac
 
-	if [[ "$OS" = 'debian' ]]; then
-		apt-get install ca-certificates -y
-		# We add the OpenVPN repo to get the latest version.
-		# Debian 7
-		if [[ "$VERSION_ID" = 'VERSION_ID="7"' ]]; then
-			os_vername=wheezy
-			bin_apt=apt-get
-		fi
-		# Debian 8
-		if [[ "$VERSION_ID" = 'VERSION_ID="8"' ]]; then
-			os_vername=jessie
-			bin_apt=apt
-		fi
-		# Ubuntu 12.04
-		if [[ "$VERSION_ID" = 'VERSION_ID="12.04"' ]]; then
-			os_vername=precise
-			bin_apt=apt-get
-		fi
-		# Ubuntu 14.04
-		if [[ "$VERSION_ID" = 'VERSION_ID="14.04"' ]]; then
-			os_vername=trusty
-			bin_apt=apt-get
-		fi
-		echo "deb http://build.openvpn.net/debian/openvpn/stable ${os_vername} main" > /etc/apt/sources.list.d/openvpn.list
-		wget -O - https://swupdate.openvpn.net/repos/repo-public.gpg | apt-key add -
-		${bin_apt} update		
-		# Ubuntu >= 16.04 and Debian > 8 have OpenVPN > 2.3.3 without the need of a third party repository.
-		
-		## The we install OpenVPN
-		apt-get install openvpn iptables openssl wget ca-certificates curl -y
-		# Install iptables service
-		if [[ ! -e /etc/systemd/system/iptables.service ]]; then
-			mkdir /etc/iptables
-			iptables-save > ${file_iptables}
-			echo "#!/bin/sh
-iptables -F
-iptables -X
-iptables -t nat -F
-iptables -t nat -X
-iptables -t mangle -F
-iptables -t mangle -X
-iptables -P INPUT ACCEPT
-iptables -P FORWARD ACCEPT
-iptables -P OUTPUT ACCEPT" > /etc/iptables/flush-iptables.sh
-			chmod +x /etc/iptables/flush-iptables.sh
-			echo "[Unit]
-Description=Packet Filtering Framework
-DefaultDependencies=no
-Before=network-pre.target
-Wants=network-pre.target
-[Service]
-Type=oneshot
-ExecStart=/sbin/iptables-restore ${file_iptables}
-ExecReload=/sbin/iptables-restore ${file_iptables}
-ExecStop=/etc/iptables/flush-iptables.sh
-RemainAfterExit=yes
-[Install]
-WantedBy=multi-user.target" > /etc/systemd/system/iptables.service
-			systemctl daemon-reload
-			systemctl enable iptables.service
-		fi
-	elif [[ "$OS" = 'centos' || "$OS" = 'fedora' ]]; then
-		if [[ "$OS" = 'centos' ]]; then
-			yum install epel-release -y
-		fi
-		yum install openvpn iptables openssl wget ca-certificates curl -y
-		# Install iptables service
-		if [[ ! -e /etc/systemd/system/iptables.service ]]; then
-			mkdir /etc/iptables
-			iptables-save > ${file_iptables}
-			echo "#!/bin/sh
-iptables -F
-iptables -X
-iptables -t nat -F
-iptables -t nat -X
-iptables -t mangle -F
-iptables -t mangle -X
-iptables -P INPUT ACCEPT
-iptables -P FORWARD ACCEPT
-iptables -P OUTPUT ACCEPT" > /etc/iptables/flush-iptables.sh
-			chmod +x /etc/iptables/flush-iptables.sh
-			echo "[Unit]
-Description=Packet Filtering Framework
-DefaultDependencies=no
-Before=network-pre.target
-Wants=network-pre.target
-[Service]
-Type=oneshot
-ExecStart=/sbin/iptables-restore ${file_iptables}
-ExecReload=/sbin/iptables-restore ${file_iptables}
-ExecStop=/etc/iptables/flush-iptables.sh
-RemainAfterExit=yes
-[Install]
-WantedBy=multi-user.target" > /etc/systemd/system/iptables.service
-			systemctl daemon-reload
-			systemctl enable iptables.service
-			# Disable firewalld to allow iptables to start upon reboot
-			systemctl disable firewalld
-			systemctl mask firewalld
-		fi
-	else
-		# Else, the distro is ArchLinux
-		echo ""
-		echo ""
-		echo "As you're using ArchLinux, I need to update the packages on your system to install those I need."
-		echo "Not doing that could cause problems between dependencies, or missing files in repositories."
-		echo ""
-		echo "Continuing will update your installed packages and install needed ones."
-		while [[ $CONTINUE != [yn] ]]; do
-			read -p "Continue ? [y/n]: " -e -i y CONTINUE
-		done
-		if [[ "$CONTINUE" = "n" ]]; then
-			echo "Ok, bye !"
-			exit 4
-		fi
+echo ""
+echo "4/6.Choose what size of Diffie-Hellman key you want to use:"
+echo "   1) 2048 bits (fastest)"
+echo "   2) 3072 bits (recommended, best compromise)"
+echo "   3) 4096 bits (most secure)"
+while [[ $DH_KEY_SIZE != [1-3] ]]; do
+	read -p "DH key size [1-3]: " -e -i 2 DH_KEY_SIZE
+done
+case $DH_KEY_SIZE in
+	1)
+	DH_KEY_SIZE="2048"
+	;;
+	2)
+	DH_KEY_SIZE="3072"
+	;;
+	3)
+	DH_KEY_SIZE="4096"
+	;;
+esac
 
-		if [[ "$OS" = 'arch' ]]; then
-			# Install dependencies
-			pacman -Syu openvpn iptables openssl wget ca-certificates curl --needed --noconfirm
-			iptables-save > ${file_iptables} # iptables won't start if this file does not exist
-			systemctl daemon-reload
-			systemctl enable iptables
-			systemctl start iptables
-		fi
+echo ""
+echo "5/6.Choose what size of RSA key you want to use:"
+echo "   1) 2048 bits (fastest)"
+echo "   2) 3072 bits (recommended, best compromise)"
+echo "   3) 4096 bits (most secure)"
+while [[ $RSA_KEY_SIZE != [1-3] ]]; do
+	read -p "RSA key size [1-3]: " -e -i 2 RSA_KEY_SIZE
+done
+case $RSA_KEY_SIZE in
+	1)
+	RSA_KEY_SIZE="2048"
+	;;
+	2)
+	RSA_KEY_SIZE="3072"
+	;;
+	3)
+	RSA_KEY_SIZE="4096"
+	;;
+esac
+
+echo ""
+echo "6/6.Finally, tell me a name for the client certificate and configuration"
+while [[ $CLIENT = "" ]]; do
+	echo "Please, use one word only, no special characters"
+	read -p "Client name: " -e -i client CLIENT
+done
+
+echo ""
+echo "Okay, that was all I needed. We are ready to setup your OpenVPN server now"
+read -n1 -r -p "Press any key to continue..."
+
+if [[ "$OS" = 'debian' ]]; then
+	apt-get install ca-certificates -y
+	# We add the OpenVPN repo to get the latest version.
+	# Debian 7
+	if [[ "$VERSION_ID" = 'VERSION_ID="7"' ]]; then
+		os_vername=wheezy
+		bin_apt=apt-get
 	fi
-	# Find out if the machine uses nogroup or nobody for the permissionless group
-	if grep -qs "^nogroup:" /etc/group; then
-		NOGROUP=nogroup
-	else
-		NOGROUP=nobody
+	# Debian 8
+	if [[ "$VERSION_ID" = 'VERSION_ID="8"' ]]; then
+		os_vername=jessie
+		bin_apt=apt
 	fi
-	## function install_easyrsa
-	install_easyrsa
+	# Ubuntu 12.04
+	if [[ "$VERSION_ID" = 'VERSION_ID="12.04"' ]]; then
+		os_vername=precise
+		bin_apt=apt-get
+	fi
+	# Ubuntu 14.04
+	if [[ "$VERSION_ID" = 'VERSION_ID="14.04"' ]]; then
+		os_vername=trusty
+		bin_apt=apt-get
+	fi
+	echo "deb http://build.openvpn.net/debian/openvpn/stable ${os_vername} main" > /etc/apt/sources.list.d/openvpn.list
+	wget -O - https://swupdate.openvpn.net/repos/repo-public.gpg | apt-key add -
+	${bin_apt} update		
+	# Ubuntu >= 16.04 and Debian > 8 have OpenVPN > 2.3.3 without the need of a third party repository.
 	
-	cd ${dir_easy}/
-	echo "set_var EASYRSA_KEY_SIZE $RSA_KEY_SIZE" > vars
-	# Create the PKI, set up the CA, the DH params and the server + client certificates
-	./easyrsa init-pki
-	./easyrsa --batch build-ca nopass
-	openssl dhparam -out dh.pem $DH_KEY_SIZE
-	./easyrsa build-server-full server nopass
-	./easyrsa build-client-full $CLIENT nopass
-	EASYRSA_CRL_DAYS=3650 ./easyrsa gen-crl
-	# generate tls-auth key
-	openvpn --genkey --secret /etc/openvpn/tls-auth.key
-	# Move all the generated files
-	cp pki/ca.crt pki/private/ca.key dh.pem pki/issued/server.crt pki/private/server.key ${dir_easy}/pki/crl.pem /etc/openvpn/
-	# Make cert revocation list readable for non-root
-	chmod 644 /etc/openvpn/crl.pem
+	## The we install OpenVPN
+	apt-get install openvpn iptables openssl wget ca-certificates curl -y
+	# Install iptables service
+	if [[ ! -e /etc/systemd/system/iptables.service ]]; then
+		mkdir /etc/iptables
+		iptables-save > ${file_iptables}
+		echo "#!/bin/sh
+iptables -F
+iptables -X
+iptables -t nat -F
+iptables -t nat -X
+iptables -t mangle -F
+iptables -t mangle -X
+iptables -P INPUT ACCEPT
+iptables -P FORWARD ACCEPT
+iptables -P OUTPUT ACCEPT" > /etc/iptables/flush-iptables.sh
+		chmod +x /etc/iptables/flush-iptables.sh
+		echo "[Unit]
+Description=Packet Filtering Framework
+DefaultDependencies=no
+Before=network-pre.target
+Wants=network-pre.target
+[Service]
+Type=oneshot
+ExecStart=/sbin/iptables-restore ${file_iptables}
+ExecReload=/sbin/iptables-restore ${file_iptables}
+ExecStop=/etc/iptables/flush-iptables.sh
+RemainAfterExit=yes
+[Install]
+WantedBy=multi-user.target" > /etc/systemd/system/iptables.service
+		systemctl daemon-reload
+		systemctl enable iptables.service
+	fi
+elif [[ "$OS" = 'centos' || "$OS" = 'fedora' ]]; then
+	if [[ "$OS" = 'centos' ]]; then
+		yum install epel-release -y
+	fi
+	yum install openvpn iptables openssl wget ca-certificates curl -y
+	# Install iptables service
+	if [[ ! -e /etc/systemd/system/iptables.service ]]; then
+		mkdir /etc/iptables
+		iptables-save > ${file_iptables}
+		echo "#!/bin/sh
+iptables -F
+iptables -X
+iptables -t nat -F
+iptables -t nat -X
+iptables -t mangle -F
+iptables -t mangle -X
+iptables -P INPUT ACCEPT
+iptables -P FORWARD ACCEPT
+iptables -P OUTPUT ACCEPT" > /etc/iptables/flush-iptables.sh
+		chmod +x /etc/iptables/flush-iptables.sh
+		echo "[Unit]
+Description=Packet Filtering Framework
+DefaultDependencies=no
+Before=network-pre.target
+Wants=network-pre.target
+[Service]
+Type=oneshot
+ExecStart=/sbin/iptables-restore ${file_iptables}
+ExecReload=/sbin/iptables-restore ${file_iptables}
+ExecStop=/etc/iptables/flush-iptables.sh
+RemainAfterExit=yes
+[Install]
+WantedBy=multi-user.target" > /etc/systemd/system/iptables.service
+		systemctl daemon-reload
+		systemctl enable iptables.service
+		# Disable firewalld to allow iptables to start upon reboot
+		systemctl disable firewalld
+		systemctl mask firewalld
+	fi
+else
+	# Else, the distro is ArchLinux
+	echo ""
+	echo ""
+	echo "As you're using ArchLinux, I need to update the packages on your system to install those I need."
+	echo "Not doing that could cause problems between dependencies, or missing files in repositories."
+	echo ""
+	echo "Continuing will update your installed packages and install needed ones."
+	while [[ $CONTINUE != [yn] ]]; do
+		read -p "Continue ? [y/n]: " -e -i y CONTINUE
+	done
+	if [[ "$CONTINUE" = "n" ]]; then
+		echo "Ok, bye !"
+		exit 4
+	fi
 
-	# Generate server.conf
-	echo "port $PORT
+	if [[ "$OS" = 'arch' ]]; then
+		# Install dependencies
+		pacman -Syu openvpn iptables openssl wget ca-certificates curl --needed --noconfirm
+		iptables-save > ${file_iptables} # iptables won't start if this file does not exist
+		systemctl daemon-reload
+		systemctl enable iptables
+		systemctl start iptables
+	fi
+fi
+
+# Find out if the machine uses nogroup or nobody for the permissionless group
+if grep -qs "^nogroup:" /etc/group; then
+	NOGROUP=nogroup
+else
+	NOGROUP=nobody
+fi
+## function install_easyrsa
+install_easyrsa
+
+cd ${dir_easy}/
+echo "set_var EASYRSA_KEY_SIZE $RSA_KEY_SIZE" > vars
+# Create the PKI, set up the CA, the DH params and the server + client certificates
+./easyrsa init-pki
+./easyrsa --batch build-ca nopass
+openssl dhparam -out dh.pem $DH_KEY_SIZE
+./easyrsa build-server-full server nopass
+./easyrsa build-client-full $CLIENT nopass
+EASYRSA_CRL_DAYS=3650 ./easyrsa gen-crl
+# generate tls-auth key
+openvpn --genkey --secret /etc/openvpn/tls-auth.key
+# Move all the generated files
+cp pki/ca.crt pki/private/ca.key dh.pem pki/issued/server.crt pki/private/server.key ${dir_easy}/pki/crl.pem /etc/openvpn/
+# Make cert revocation list readable for non-root
+chmod 644 /etc/openvpn/crl.pem
+
+# Generate server.conf
+echo "port $PORT
 proto ${PROTOCOL}
 dev tun
 user nobody
@@ -454,42 +426,42 @@ keepalive 10 120
 topology subnet
 server 10.8.0.0 255.255.255.0
 ifconfig-pool-persist ipp.txt" >> /etc/openvpn/server.conf
-	# DNS resolvers
-	case $DNS in
-		1)
-		# Obtain the resolvers from resolv.conf and use them for OpenVPN
-		grep -v '#' /etc/resolv.conf | grep 'nameserver' | grep -E -o '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | while read line; do
-			echo "push \"dhcp-option DNS $line\"" 
-		done
-		;;
-		2) #Quad9
-		echo 'push "dhcp-option DNS 9.9.9.9"' 
-		;;
-		3) #FDN
-		echo 'push "dhcp-option DNS 80.67.169.12"'
-		echo 'push "dhcp-option DNS 80.67.169.40"'
-		;;
-		4) #DNS.WATCH
-		echo 'push "dhcp-option DNS 84.200.69.80"'
-		echo 'push "dhcp-option DNS 84.200.70.40"'
-		;;
-		5) #OpenDNS
-		echo 'push "dhcp-option DNS 208.67.222.222"'
-		echo 'push "dhcp-option DNS 208.67.220.220"'
-		;;
-		6) #Google
-		echo 'push "dhcp-option DNS 8.8.8.8"'
-		echo 'push "dhcp-option DNS 8.8.4.4"'
-		;;
-		7) #Yandex Basic
-		echo 'push "dhcp-option DNS 77.88.8.8"'
-		echo 'push "dhcp-option DNS 77.88.8.1"'
-		;;
-		8) #AdGuard DNS
-		echo 'push "dhcp-option DNS 176.103.130.130"'
-		echo 'push "dhcp-option DNS 176.103.130.131"'
-		;;
-	esac >> /etc/openvpn/server.conf
+# DNS resolvers
+case $DNS in
+	1)
+	# Obtain the resolvers from resolv.conf and use them for OpenVPN
+	grep -v '#' /etc/resolv.conf | grep 'nameserver' | grep -E -o '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | while read line; do
+		echo "push \"dhcp-option DNS $line\"" 
+	done
+	;;
+	2) #Quad9
+	echo 'push "dhcp-option DNS 9.9.9.9"' 
+	;;
+	3) #FDN
+	echo 'push "dhcp-option DNS 80.67.169.12"'
+	echo 'push "dhcp-option DNS 80.67.169.40"'
+	;;
+	4) #DNS.WATCH
+	echo 'push "dhcp-option DNS 84.200.69.80"'
+	echo 'push "dhcp-option DNS 84.200.70.40"'
+	;;
+	5) #OpenDNS
+	echo 'push "dhcp-option DNS 208.67.222.222"'
+	echo 'push "dhcp-option DNS 208.67.220.220"'
+	;;
+	6) #Google
+	echo 'push "dhcp-option DNS 8.8.8.8"'
+	echo 'push "dhcp-option DNS 8.8.4.4"'
+	;;
+	7) #Yandex Basic
+	echo 'push "dhcp-option DNS 77.88.8.8"'
+	echo 'push "dhcp-option DNS 77.88.8.1"'
+	;;
+	8) #AdGuard DNS
+	echo 'push "dhcp-option DNS 176.103.130.130"'
+	echo 'push "dhcp-option DNS 176.103.130.131"'
+	;;
+esac >> /etc/openvpn/server.conf
 echo 'push "redirect-gateway def1 bypass-dhcp" '>> /etc/openvpn/server.conf
 echo "crl-verify crl.pem
 ca ca.crt
@@ -505,64 +477,64 @@ tls-cipher TLS-DHE-RSA-WITH-AES-128-GCM-SHA256
 status openvpn.log
 verb 3" >> /etc/openvpn/server.conf
 
-	## function set_firewall 
-	set_firewall
+## call function set_firewall 
+set_firewall
 	
-	# And finally, restart OpenVPN
-	if [[ "$OS" = 'debian' ]]; then
-		# Little hack to check for systemd
-		if pgrep systemd-journal; then
-				#Workaround to fix OpenVPN service on OpenVZ
-				sed -i 's|LimitNPROC|#LimitNPROC|' /lib/systemd/system/openvpn\@.service
-				sed -i 's|/etc/openvpn/server|/etc/openvpn|' /lib/systemd/system/openvpn\@.service
-				sed -i 's|%i.conf|server.conf|' /lib/systemd/system/openvpn\@.service
-				systemctl daemon-reload
-				systemctl restart openvpn
-				systemctl enable openvpn
+# And finally, restart OpenVPN
+if [[ "$OS" = 'debian' ]]; then
+	# Little hack to check for systemd
+	if pgrep systemd-journal; then
+			#Workaround to fix OpenVPN service on OpenVZ
+			sed -i 's|LimitNPROC|#LimitNPROC|' /lib/systemd/system/openvpn\@.service
+			sed -i 's|/etc/openvpn/server|/etc/openvpn|' /lib/systemd/system/openvpn\@.service
+			sed -i 's|%i.conf|server.conf|' /lib/systemd/system/openvpn\@.service
+			systemctl daemon-reload
+			systemctl restart openvpn
+			systemctl enable openvpn
+	else
+		/etc/init.d/openvpn restart
+	fi
+else
+	if pgrep systemd-journal; then
+		if [[ "$OS" = 'arch' || "$OS" = 'fedora' ]]; then
+			#Workaround to avoid rewriting the entire script for Arch & Fedora
+			sed -i 's|/etc/openvpn/server|/etc/openvpn|' /usr/lib/systemd/system/openvpn-server@.service
+			sed -i 's|%i.conf|server.conf|' /usr/lib/systemd/system/openvpn-server@.service
+			systemctl daemon-reload
+			systemctl restart openvpn-server@openvpn.service
+			systemctl enable openvpn-server@openvpn.service
 		else
-			/etc/init.d/openvpn restart
+			systemctl restart openvpn@server.service
+			systemctl enable openvpn@server.service
 		fi
 	else
-		if pgrep systemd-journal; then
-			if [[ "$OS" = 'arch' || "$OS" = 'fedora' ]]; then
-				#Workaround to avoid rewriting the entire script for Arch & Fedora
-				sed -i 's|/etc/openvpn/server|/etc/openvpn|' /usr/lib/systemd/system/openvpn-server@.service
-				sed -i 's|%i.conf|server.conf|' /usr/lib/systemd/system/openvpn-server@.service
-				systemctl daemon-reload
-				systemctl restart openvpn-server@openvpn.service
-				systemctl enable openvpn-server@openvpn.service
-			else
-				systemctl restart openvpn@server.service
-				systemctl enable openvpn@server.service
-			fi
-		else
-			service openvpn restart
-			chkconfig openvpn on
-		fi
+		service openvpn restart
+		chkconfig openvpn on
 	fi
-	# Try to detect a NATed connection and ask about it to potential LowEndSpirit/Scaleway users
-	EXTERNALIP=$(wget -qO- ipv4.icanhazip.com)
-	if [[ "$IP" != "$EXTERNALIP" ]]; then
-		echo ""
-		echo "Looks like your server is behind a NAT!"
-		echo ""
-        echo "If your server is NATed (e.g. LowEndSpirit, Scaleway, or behind a router),"
-        echo "then I need to know the address that can be used to access it from outside."
-        echo "If that's not the case, just ignore this and leave the next field blank"
-        read -p "External IP or domain name: " -e USEREXTERNALIP
-		if [[ "$USEREXTERNALIP" != "" ]]; then
-			IP=$USEREXTERNALIP
-		fi
+fi
+# Try to detect a NATed connection and ask about it to potential LowEndSpirit/Scaleway users
+EXTERNALIP=$(wget -qO- ipv4.icanhazip.com)
+if [[ "$IP" != "$EXTERNALIP" ]]; then
+	echo ""
+	echo "Looks like your server is behind a NAT!"
+	echo ""
+	echo "If your server is NATed (e.g. LowEndSpirit, Scaleway, or behind a router),"
+	echo "then I need to know the address that can be used to access it from outside."
+	echo "If that's not the case, just ignore this and leave the next field blank"
+	read -p "External IP or domain name: " -e USEREXTERNALIP
+	if [[ "$USEREXTERNALIP" != "" ]]; then
+		IP=$USEREXTERNALIP
 	fi
+fi
 	
-	# client-template.txt is created so we have a template to add further users later
-	echo "client" > ${file_client_tpl}
-	if [[ "$PROTOCOL" = 'udp' ]]; then
-		echo "proto ${PROTOCOL}" >> ${file_client_tpl}
-	elif [[ "$PROTOCOL" = 'tcp' ]]; then
-		echo "proto ${PROTOCOL}-client" >> ${file_client_tpl}
-	fi
-	echo "remote $IP $PORT
+# client-template.txt is created so we have a template to add further users later
+echo "client" > ${file_client_tpl}
+if [[ "$PROTOCOL" = 'udp' ]]; then
+	echo "proto ${PROTOCOL}" >> ${file_client_tpl}
+elif [[ "$PROTOCOL" = 'tcp' ]]; then
+	echo "proto ${PROTOCOL}-client" >> ${file_client_tpl}
+fi
+echo "remote $IP $PORT
 dev tun
 resolv-retry infinite
 nobind
@@ -578,36 +550,22 @@ tls-cipher TLS-DHE-RSA-WITH-AES-128-GCM-SHA256
 setenv opt block-outside-dns
 verb 3" >> ${file_client_tpl}
 
-	# function Generate the custom client.ovpn
-	newclient "$CLIENT"
-	echo ""
-	echo "Finished!"
-	echo ""
-	echo "Your client config is available at $homeDir/$CLIENT.ovpn"
-	echo "If you want to add more clients, you simply need to run this script another time!"
+# call function Generate the custom client.ovpn
+generate_newclient "$CLIENT"
+echo ""
+echo "Finished!"
+echo ""
+echo "Your client config is available at $homeDir/$CLIENT.ovpn"
+echo "If you want to add more clients, you simply need to run this script another time!"
 }
 
-detect_IP_NIC(){
-# Try to get our IP from the system and fallback to the Internet.
-# I do this to make the script compatible with NATed servers (LowEndSpirit/Scaleway)
-# and to avoid getting an IPv6.
-IP=$(ip addr | grep 'inet' | grep -v inet6 | grep -vE '127\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | grep -o -E '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | head -1)
-if [[ "$IP" = "" ]]; then
-	IP=$(wget -qO- ipv4.icanhazip.com)
-fi
-# Get Internet network interface with default route
-NIC=$(ip -4 route ls | grep default | grep -Po '(?<=dev )(\S+)' | head -1)
-
-
-}
 
 config_openvpn(){
 
-
-	while :
-	do
-		clear
-cat <<EOF
+while :
+do
+	clear
+	cat <<EOF
 OpenVPN-install (github.com/Angristan/OpenVPN-install)
 
 Looks like OpenVPN is already installed
@@ -618,116 +576,167 @@ What do you want to do?
    3) Remove OpenVPN
    4) Exit
 EOF
-		file_index="${dir_easy}/pki/index.txt"
-		read -p 'Select an option [1-4]: ' option
-		case $option in
-			1)
+	file_index="${dir_easy}/pki/index.txt"
+	read -p 'Select an option [1-4]: ' option
+	case $option in
+		1)
+		echo ""
+		echo "Tell me a name for the client cert"
+		echo "Please, use one word only, no special characters"
+		echo "Here are the files that already exist,do not repeat that"
+		tail -n +2 ${file_index} | grep "^V" | cut -d '=' -f 2 | nl -s ') '
+		read -p "Client name: " -e -i client CLIENT
+		cd ${dir_easy}
+		${bin_easy} build-client-full $CLIENT nopass
+		# Generates the custom client.ovpn
+		generate_newclient "$CLIENT"
+		echo ""
+		echo "Client $CLIENT added, certs available at $homeDir/$CLIENT.ovpn"
+		exit
+		;;
+		2)
+		NUMBEROFCLIENTS=$(tail -n +2 ${file_index} | grep -c "^V")
+		if [[ "$NUMBEROFCLIENTS" = '0' ]]; then
 			echo ""
-			echo "Tell me a name for the client cert"
-			echo "Please, use one word only, no special characters"
-			echo "Here are the files that already exist,do not repeat that"
-			tail -n +2 ${file_index} | grep "^V" | cut -d '=' -f 2 | nl -s ') '
-			read -p "Client name: " -e -i client CLIENT
-			cd ${dir_easy}
-			${bin_easy} build-client-full $CLIENT nopass
-			# Generates the custom client.ovpn
-			newclient "$CLIENT"
-			echo ""
-			echo "Client $CLIENT added, certs available at $homeDir/$CLIENT.ovpn"
-			exit
-			;;
-			2)
-			NUMBEROFCLIENTS=$(tail -n +2 ${file_index} | grep -c "^V")
-			if [[ "$NUMBEROFCLIENTS" = '0' ]]; then
-				echo ""
-				echo "You have no existing clients!"
-				exit 5
+			echo "You have no existing clients!"
+			exit 5
+		fi
+		echo ""
+		echo "Select the existing client certificate you want to revoke"
+		tail -n +2 ${file_index} | grep "^V" | cut -d '=' -f 2 | nl -s ') '
+		if [[ "$NUMBEROFCLIENTS" = '1' ]]; then
+			read -p "Select one client [1]: " CLIENTNUMBER
+		else
+			read -p "Select one client [1-$NUMBEROFCLIENTS]: " CLIENTNUMBER
+		fi
+		CLIENT=$(tail -n +2 ${file_index} | grep "^V" | cut -d '=' -f 2 | sed -n "$CLIENTNUMBER"p)
+		cd ${dir_easy}
+		${bin_easy} --batch revoke $CLIENT
+		EASYRSA_CRL_DAYS=3650 ${bin_easy} gen-crl
+		rm -f ${dir_pki}/reqs/$CLIENT.req ${dir_pki}/private/$CLIENT.key ${dir_pki}/issued/$CLIENT.crt 
+		#rm -f ${dir_openvpn}/crl.pem
+		/bin/cp -f ${dir_pki}/crl.pem ${dir_openvpn}/crl.pem
+		chmod 644 ${dir_openvpn}/crl.pem
+		echo ""
+		echo "Certificate for client $CLIENT revoked"
+		echo "Exiting..."
+		exit
+		;;
+		3)
+		echo ""
+		read -p "Do you really want to remove OpenVPN? [y/n]: " -e -i n REMOVE
+		if [[ 'y' = "$REMOVE" ]]; then
+			PORT=$(grep '^port ' ${file_openvpn_conf} | cut -d " " -f 2)
+			PROTOCOL=$(grep '^proto ' ${file_openvpn_conf} | cut -d " " -f 2)
+			if pgrep firewalld; then
+				# Using both permanent and not permanent rules to avoid a firewalld reload.
+				firewall-cmd --zone=public --remove-port=$PORT/${PROTOCOL}
+				firewall-cmd --zone=trusted --remove-source=10.8.0.0/24
+				firewall-cmd --permanent --zone=public --remove-port=$PORT/${PROTOCOL}
+				firewall-cmd --permanent --zone=trusted --remove-source=10.8.0.0/24
 			fi
-			echo ""
-			echo "Select the existing client certificate you want to revoke"
-			tail -n +2 ${file_index} | grep "^V" | cut -d '=' -f 2 | nl -s ') '
-			if [[ "$NUMBEROFCLIENTS" = '1' ]]; then
-				read -p "Select one client [1]: " CLIENTNUMBER
-			else
-				read -p "Select one client [1-$NUMBEROFCLIENTS]: " CLIENTNUMBER
-			fi
-			CLIENT=$(tail -n +2 ${file_index} | grep "^V" | cut -d '=' -f 2 | sed -n "$CLIENTNUMBER"p)
-			cd ${dir_easy}
-			${bin_easy} --batch revoke $CLIENT
-			EASYRSA_CRL_DAYS=3650 ${bin_easy} gen-crl
-			rm -f ${dir_pki}/reqs/$CLIENT.req ${dir_pki}/private/$CLIENT.key ${dir_pki}/issued/$CLIENT.crt 
-			#rm -f ${dir_openvpn}/crl.pem
-			/bin/cp -f ${dir_pki}/crl.pem ${dir_openvpn}/crl.pem
-			chmod 644 ${dir_openvpn}/crl.pem
-			echo ""
-			echo "Certificate for client $CLIENT revoked"
-			echo "Exiting..."
-			exit
-			;;
-			3)
-			echo ""
-			read -p "Do you really want to remove OpenVPN? [y/n]: " -e -i n REMOVE
-			if [[ 'y' = "$REMOVE" ]]; then
-				PORT=$(grep '^port ' ${file_openvpn_conf} | cut -d " " -f 2)
-				PROTOCOL=$(grep '^proto ' ${file_openvpn_conf} | cut -d " " -f 2)
-				if pgrep firewalld; then
-					# Using both permanent and not permanent rules to avoid a firewalld reload.
-					firewall-cmd --zone=public --remove-port=$PORT/${PROTOCOL}
-					firewall-cmd --zone=trusted --remove-source=10.8.0.0/24
-					firewall-cmd --permanent --zone=public --remove-port=$PORT/${PROTOCOL}
-					firewall-cmd --permanent --zone=trusted --remove-source=10.8.0.0/24
-				fi
-				if iptables -L -n | grep -qE 'REJECT|DROP'; then
-					iptables -D INPUT -p ${PROTOCOL} --dport $PORT -j ACCEPT
-					iptables -D FORWARD -s 10.8.0.0/24 -j ACCEPT
-					iptables-save > $file_iptables
-				fi
-				iptables -t nat -D POSTROUTING -o $NIC -s 10.8.0.0/24 -j MASQUERADE
+			if iptables -L -n | grep -qE 'REJECT|DROP'; then
+				iptables -D INPUT -p ${PROTOCOL} --dport $PORT -j ACCEPT
+				iptables -D FORWARD -s 10.8.0.0/24 -j ACCEPT
 				iptables-save > $file_iptables
-				if hash sestatus 2>/dev/null; then
-					if sestatus | grep "Current mode" | grep -qs "enforcing"; then
-						if [[ "$PORT" != '1194' ]]; then
-							semanage port -d -t openvpn_port_t -p ${PROTOCOL} $PORT
-						fi
+			fi
+			iptables -t nat -D POSTROUTING -o $NIC -s 10.8.0.0/24 -j MASQUERADE
+			iptables-save > $file_iptables
+			if hash sestatus 2>/dev/null; then
+				if sestatus | grep "Current mode" | grep -qs "enforcing"; then
+					if [[ "$PORT" != '1194' ]]; then
+						semanage port -d -t openvpn_port_t -p ${PROTOCOL} $PORT
 					fi
 				fi
-				if [[ "$OS" = 'debian' ]]; then
-					apt-get autoremove --purge -y openvpn
-				elif [[ "$OS" = 'arch' ]]; then
-					pacman -R openvpn --noconfirm
-				else
-					yum remove openvpn -y
-				fi
-				rm -rf ${dir_openvpn} /usr/share/doc/openvpn*
-				echo ""
-				echo "OpenVPN removed!"
-			else
-				echo ""
-				echo "Removal aborted!"
 			fi
-			exit
-			;;
-			4) exit;;
-		esac
-	done
+			if [[ "$OS" = 'debian' ]]; then
+				apt-get autoremove --purge -y openvpn
+			elif [[ "$OS" = 'arch' ]]; then
+				pacman -R openvpn --noconfirm
+			else
+				yum remove openvpn -y
+			fi
+			rm -rf ${dir_openvpn} /usr/share/doc/openvpn*
+			echo ""
+			echo "OpenVPN removed!"
+		else
+			echo ""
+			echo "Removal aborted!"
+		fi
+		exit
+		;;
+		4) exit;;
+	esac
+done
 
 }
 
+## function: determine the operating system version
+detect_os_ver(){
+
+if [[ -e /etc/debian_version ]]; then
+	OS="debian"
+	# Getting the version number, to verify that a recent version of OpenVPN is available
+	VERSION_ID=$(grep "VERSION_ID" /etc/os-release)
+	SYSCTL='/etc/sysctl.conf'
+	if [[ "$VERSION_ID" != 'VERSION_ID="7"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="8"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="9"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="12.04"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="14.04"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="16.04"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="16.10"' ]] && [[ "$VERSION_ID" != 'VERSION_ID="17.04"' ]]; then
+		echo 'Your version of Debian/Ubuntu is not supported.'
+		echo "I can't install a recent version of OpenVPN on your system."
+		echo ''
+		echo "However, if you're using Debian unstable/testing, or Ubuntu beta,"
+		echo 'then you can continue, a recent version of OpenVPN is available on these.'
+		echo 'Keep in mind they are not supported, though.'
+		while [[ "$CONTINUE" != [yn]  ]]; do
+			read -p 'Continue ? [y/n]: ' -e CONTINUE
+		done
+		if [[ 'n' = "$CONTINUE" ]]; then
+			echo 'Ok, bye !'
+			exit 4
+		fi
+	fi
+elif [[ -e /etc/centos-release || -e /etc/redhat-release && ! -e /etc/fedora-release ]]; then
+	OS='centos'
+	SYSCTL='/etc/sysctl.conf'
+elif [[ -e /etc/arch-release ]]; then
+	OS='arch'
+	SYSCTL='/etc/sysctl.d/openvpn.conf'
+elif [[ -e /etc/fedora-release ]]; then
+	OS='fedora'
+	SYSCTL='/etc/sysctl.d/openvpn.conf'
+else
+	echo "Looks like you aren't running this installer on a Debian, Ubuntu, CentOS or ArchLinux system"
+	exit 4
+fi
+}
+
+detect_IP_NIC(){
+
+# Try to get our IP from the system and fallback to the Internet.
+# I do this to make the script compatible with NATed servers (LowEndSpirit/Scaleway)
+# and to avoid getting an IPv6.
+IP=$(ip addr | grep 'inet' | grep -v inet6 | grep -vE '127\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | grep -o -E '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | head -1)
+if [[ "$IP" = "" ]]; then
+	IP=$(wget -qO- ipv4.icanhazip.com)
+fi
+# Get Internet network interface with default route
+NIC=$(ip -4 route ls | grep default | grep -Po '(?<=dev )(\S+)' | head -1)
+}
 
 ################################# main #################################
-detect_os_ver
-detect_IP_NIC
+main(){
+detect_os_ver ## call function
+detect_IP_NIC ## call function
 
 ## OpenVPN setup and first user creation
 if [[ ! -e ${file_openvpn_conf} ]]; then
-	install_openvpn
+	install_openvpn ## call function
 fi
 
 #### server.conf exist.
 if [[ -e ${file_openvpn_conf} ]]; then
-	config_openvpn
+	config_openvpn ## call function
 fi
+}
 
-
-
-exit 0;
+main $@
+# exit 0;