From 14c067f66c41b0f5edc6b818ba6fc5eb09c8bb44 Mon Sep 17 00:00:00 2001
From: simono41 <simono41>
Date: Thu, 12 Oct 2017 01:39:20 +0200
Subject: [PATCH] fix-script

---
 openvpn-install.sh | 647 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 647 insertions(+)
 create mode 100755 openvpn-install.sh

diff --git a/openvpn-install.sh b/openvpn-install.sh
new file mode 100755
index 0000000..feeb70e
--- /dev/null
+++ b/openvpn-install.sh
@@ -0,0 +1,647 @@
+#!/bin/bash
+
+set -ex
+
+# Secure OpenVPN server installer for Debian, Ubuntu, CentOS and Arch Linux
+# https://github.com/Angristan/OpenVPN-install
+
+
+if [[ "$EUID" -ne 0 ]]; then
+	echo "Sorry, you need to run this as root"
+	exit 1
+fi
+
+if [[ ! -e /dev/net/tun ]]; then
+	echo "TUN is not available"
+	exit 2
+fi
+
+if grep -qs "CentOS release 5" "/etc/redhat-release"; then
+	echo "CentOS 5 is too old and not supported"
+	exit 3
+fi
+
+if [[ -e /etc/debian_version ]]; then
+	OS="debian"
+	# Getting the version number, to verify that a recent version of OpenVPN is available
+	VERSION_ID=$(cat /etc/os-release | grep "VERSION_ID")
+	RCLOCAL='/etc/rc.local'
+	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 != "y" && $CONTINUE != "n" ]]; do
+			read -p "Continue ? [y/n]: " -e CONTINUE
+		done
+		if [[ "$CONTINUE" = "n" ]]; then
+			echo "Ok, bye !"
+			exit 4
+		fi
+	fi
+elif [[ -e /etc/centos-release || -e /etc/redhat-release ]]; then
+	OS=centos
+	RCLOCAL='/etc/rc.d/rc.local'
+	SYSCTL='/etc/sysctl.conf'
+	# Needed for CentOS 7
+	chmod +x /etc/rc.d/rc.local
+elif [[ -e /etc/arch-release ]]; then
+	OS=arch
+	RCLOCAL='/etc/rc.local'
+	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
+
+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="/root"
+	fi
+	# Generates the custom client.ovpn
+	cp /etc/openvpn/client-template.txt $homeDir/$1.ovpn
+	echo "<ca>" >> $homeDir/$1.ovpn
+	cat /etc/openvpn/easy-rsa/pki/ca.crt >> $homeDir/$1.ovpn
+	echo "</ca>" >> $homeDir/$1.ovpn
+	echo "<cert>" >> $homeDir/$1.ovpn
+	cat /etc/openvpn/easy-rsa/pki/issued/$1.crt >> $homeDir/$1.ovpn
+	echo "</cert>" >> $homeDir/$1.ovpn
+	echo "<key>" >> $homeDir/$1.ovpn
+	cat /etc/openvpn/easy-rsa/pki/private/$1.key >> $homeDir/$1.ovpn
+	echo "</key>" >> $homeDir/$1.ovpn
+	echo "key-direction 1" >> $homeDir/$1.ovpn
+	echo "<tls-auth>" >> $homeDir/$1.ovpn
+	cat /etc/openvpn/tls-auth.key >> $homeDir/$1.ovpn
+	echo "</tls-auth>" >> $homeDir/$1.ovpn
+}
+
+# Try to get our IP from the system and fallback to the Internet.
+# I do this to make the script compatible with NATed servers (LowEndSpirit/Scaleway)
+# and to avoid getting an IPv6.
+IP=$(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 -m 1 | grep -Po '(?<=dev )(\S+)')
+
+if [[ -e /etc/openvpn/server.conf ]]; then
+	while :
+	do
+	clear
+		echo "OpenVPN-install (github.com/Angristan/OpenVPN-install)"
+		echo ""
+		echo "Looks like OpenVPN is already installed"
+		echo ""
+		echo "What do you want to do?"
+		echo "   1) Add a cert for a new user"
+		echo "   2) Revoke existing user cert"
+		echo "   3) Remove OpenVPN"
+		echo "   4) Exit"
+		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"
+			read -p "Client name: " -e -i client CLIENT
+			cd /etc/openvpn/easy-rsa/
+			./easyrsa 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=$(tail -n +2 /etc/openvpn/easy-rsa/pki/index.txt | grep -c "^V")
+			if [[ "$NUMBEROFCLIENTS" = '0' ]]; then
+				echo ""
+				echo "You have no existing clients!"
+				exit 5
+			fi
+			echo ""
+			echo "Select the existing client certificate you want to revoke"
+			tail -n +2 /etc/openvpn/easy-rsa/pki/index.txt | 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=$(tail -n +2 /etc/openvpn/easy-rsa/pki/index.txt | grep "^V" | cut -d '=' -f 2 | sed -n "$CLIENTNUMBER"p)
+			cd /etc/openvpn/easy-rsa/
+			./easyrsa --batch revoke $CLIENT
+			EASYRSA_CRL_DAYS=3650 ./easyrsa gen-crl
+			rm -rf pki/reqs/$CLIENT.req
+			rm -rf pki/private/$CLIENT.key
+			rm -rf pki/issued/$CLIENT.crt
+			rm -rf /etc/openvpn/crl.pem
+			cp /etc/openvpn/easy-rsa/pki/crl.pem /etc/openvpn/crl.pem
+			chmod 644 /etc/openvpn/crl.pem
+			echo ""
+			echo "Certificate for client $CLIENT revoked"
+			echo "Exiting..."
+			exit
+			;;
+			3)
+			echo ""
+			read -p "Do you really want to remove OpenVPN? [y/n]: " -e -i n REMOVE
+			if [[ "$REMOVE" = 'y' ]]; then
+				PORT=$(grep '^port ' /etc/openvpn/server.conf | cut -d " " -f 2)
+				if pgrep firewalld; then
+					# Using both permanent and not permanent rules to avoid a firewalld reload.
+					firewall-cmd --zone=public --remove-port=$PORT/udp
+					firewall-cmd --zone=trusted --remove-source=10.8.0.0/24
+					firewall-cmd --permanent --zone=public --remove-port=$PORT/udp
+					firewall-cmd --permanent --zone=trusted --remove-source=10.8.0.0/24
+				fi
+				if iptables -L -n | grep -qE 'REJECT|DROP'; then
+					sed -i "/iptables -I INPUT -p udp --dport $PORT -j ACCEPT/d" $RCLOCAL
+					sed -i "/iptables -I FORWARD -s 10.8.0.0\/24 -j ACCEPT/d" $RCLOCAL
+					sed -i "/iptables -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT/d" $RCLOCAL
+				fi
+				sed -i '/iptables -t nat -A POSTROUTING -s 10.8.0.0\/24 -j SNAT --to /d' $RCLOCAL
+				if hash sestatus 2>/dev/null; then
+					if sestatus | grep "Current mode" | grep -qs "enforcing"; then
+						if [[ "$PORT" != '1194' ]]; then
+							semanage port -d -t openvpn_port_t -p udp $PORT
+						fi
+					fi
+				fi
+				if [[ "$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 /etc/openvpn
+				rm -rf /usr/share/doc/openvpn*
+				echo ""
+				echo "OpenVPN removed!"
+			else
+				echo ""
+				echo "Removal aborted!"
+			fi
+			exit
+			;;
+			4) exit;;
+		esac
+	done
+else
+	clear
+	echo "Welcome to the secure OpenVPN installer (github.com/Angristan/OpenVPN-install)"
+	echo ""
+	# OpenVPN setup and first user creation
+	echo "I need to ask you a few questions before starting the setup"
+	echo "You can leave the default options and just press enter if you are ok with them"
+	echo ""
+	echo "I need to know the IPv4 address of the network interface you want OpenVPN listening to."
+	echo "If your server is running behind a NAT, (e.g. LowEndSpirit, Scaleway) leave the IP address as it is. (local/private IP)"
+	echo "Otherwise, it should be your public IPv4 address."
+	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 "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
+	echo ""
+	echo "What DNS do you want to use with the VPN?"
+	echo "   1) Current system resolvers (in /etc/resolv.conf)"
+	echo "   2) FDN (France)"
+	echo "   3) DNS.WATCH (Germany)"
+	echo "   4) OpenDNS (Anycast: worldwide)"
+	echo "   5) Google (Anycast: worldwide)"
+	echo "   6) Yandex Basic (Russia)"
+	echo "   7) AdGuard DNS (Russia)"
+	while [[ $DNS != "1" && $DNS != "2" && $DNS != "3" && $DNS != "4" && $DNS != "5" && $DNS != "6" && $DNS != "7" ]]; do
+		read -p "DNS [1-7]: " -e -i 1 DNS
+	done
+	echo ""
+	echo "See https://github.com/Angristan/OpenVPN-install#encryption to learn more about "
+	echo "the encryption in OpenVPN and the choices I made in this script."
+	echo "Please note that all the choices proposed are secure (to a different degree)"
+	echo "and are still viable to date, unlike some default OpenVPN options"
+	echo ''
+	echo "Choose which cipher you want to use for the data channel:"
+	echo "   1) AES-128-CBC (fastest and sufficiently secure for everyone, recommended)"
+	echo "   2) AES-192-CBC"
+	echo "   3) AES-256-CBC"
+	echo "Alternatives to AES, use them only if you know what you're doing."
+	echo "They are relatively slower but as secure as AES."
+	echo "   4) CAMELLIA-128-CBC"
+	echo "   5) CAMELLIA-192-CBC"
+	echo "   6) CAMELLIA-256-CBC"
+	echo "   7) SEED-CBC"
+	while [[ $CIPHER != "1" && $CIPHER != "2" && $CIPHER != "3" && $CIPHER != "4" && $CIPHER != "5" && $CIPHER != "6" && $CIPHER != "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 "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" && $DH_KEY_SIZE != "2" && $DH_KEY_SIZE != "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 "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" && $RSA_KEY_SIZE != "2" && $RSA_KEY_SIZE != "3" ]]; do
+		read -p "DH 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 "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 [[ "$VERSION_ID" = 'VERSION_ID="7"' ]]; then
+			echo "deb http://build.openvpn.net/debian/openvpn/stable wheezy main" > /etc/apt/sources.list.d/openvpn.list
+			wget -O - https://swupdate.openvpn.net/repos/repo-public.gpg | apt-key add -
+			apt-get update
+		fi
+		# Debian 8
+		if [[ "$VERSION_ID" = 'VERSION_ID="8"' ]]; then
+			echo "deb http://build.openvpn.net/debian/openvpn/stable jessie main" > /etc/apt/sources.list.d/openvpn.list
+			wget -O - https://swupdate.openvpn.net/repos/repo-public.gpg | apt-key add -
+			apt update
+		fi
+		# Ubuntu 12.04
+		if [[ "$VERSION_ID" = 'VERSION_ID="12.04"' ]]; then
+			echo "deb http://build.openvpn.net/debian/openvpn/stable precise main" > /etc/apt/sources.list.d/openvpn.list
+			wget -O - https://swupdate.openvpn.net/repos/repo-public.gpg | apt-key add -
+			apt-get update
+		fi
+		# Ubuntu 14.04
+		if [[ "$VERSION_ID" = 'VERSION_ID="14.04"' ]]; then
+			echo "deb http://build.openvpn.net/debian/openvpn/stable trusty main" > /etc/apt/sources.list.d/openvpn.list
+			wget -O - https://swupdate.openvpn.net/repos/repo-public.gpg | apt-key add -
+			apt-get update
+		fi
+		# 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
+	elif [[ "$OS" = 'centos' ]]; then
+		yum install epel-release -y
+		yum install openvpn iptables openssl wget ca-certificates curl -y
+	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 != "y" && $CONTINUE != "n" ]]; do
+			read -p "Continue ? [y/n]: " -e -i y CONTINUE
+		done
+		if [[ "$CONTINUE" = "n" ]]; then
+			echo "Ok, bye !"
+			exit 4
+		fi
+
+		if [[ "$OS" = 'arch' ]]; then
+		# Install rc.local
+		echo "[Unit]
+Description=/etc/rc.local compatibility
+
+[Service]
+Type=oneshot
+ExecStart=/etc/rc.local
+RemainAfterExit=yes
+
+[Install]
+WantedBy=multi-user.target" > /etc/systemd/system/rc-local.service
+			chmod +x /etc/rc.local
+			systemctl enable rc-local.service
+			if ! grep '#!' $RCLOCAL; then
+				echo "#!/bin/bash" > $RCLOCAL
+			fi
+		fi
+
+		# Install dependencies
+		pacman -Syu openvpn iptables openssl wget ca-certificates curl --needed --noconfirm
+		if [[ "$OS" = 'arch' ]]; then
+			touch /etc/iptables/iptables.rules # iptables won't start if this file does not exist
+			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
+
+	# An old version of easy-rsa was available by default in some openvpn packages
+	if [[ -d /etc/openvpn/easy-rsa/ ]]; then
+		rm -rf /etc/openvpn/easy-rsa/
+	fi
+	# Get easy-rsa
+	wget -O ~/EasyRSA-3.0.3.tgz https://github.com/OpenVPN/easy-rsa/releases/download/v3.0.3/EasyRSA-3.0.3.tgz
+	tar xzf ~/EasyRSA-3.0.3.tgz -C ~/
+	mv ~/EasyRSA-3.0.3/ /etc/openvpn/
+	mv /etc/openvpn/EasyRSA-3.0.3/ /etc/openvpn/easy-rsa/
+	chown -R root:root /etc/openvpn/easy-rsa/
+	rm -rf ~/EasyRSA-3.0.3.tgz
+	cd /etc/openvpn/easy-rsa/
+	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 /etc/openvpn/easy-rsa/pki/crl.pem /etc/openvpn
+	# Make cert revocation list readable for non-root
+	chmod 644 /etc/openvpn/crl.pem
+
+	# Generate server.conf
+	echo "local $IP" > /etc/openvpn/server.conf
+	echo "port $PORT" >> /etc/openvpn/server.conf
+	if [[ "$PROTOCOL" = 'UDP' ]]; then
+		echo "proto udp" >> /etc/openvpn/server.conf
+	elif [[ "$PROTOCOL" = 'TCP' ]]; then
+		echo "proto tcp" >> /etc/openvpn/server.conf
+	fi
+	echo "dev tun
+user nobody
+group $NOGROUP
+persist-key
+persist-tun
+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 $line\"" >> /etc/openvpn/server.conf
+		done
+		;;
+		2) #FDN
+		echo 'push "dhcp-option DNS 80.67.169.12"' >> /etc/openvpn/server.conf
+		echo 'push "dhcp-option DNS 80.67.169.40"' >> /etc/openvpn/server.conf
+		;;
+		3) #DNS.WATCH
+		echo 'push "dhcp-option DNS 84.200.69.80"' >> /etc/openvpn/server.conf
+		echo 'push "dhcp-option DNS 84.200.70.40"' >> /etc/openvpn/server.conf
+		;;
+		4) #OpenDNS
+		echo 'push "dhcp-option DNS 208.67.222.222"' >> /etc/openvpn/server.conf
+		echo 'push "dhcp-option DNS 208.67.220.220"' >> /etc/openvpn/server.conf
+		;;
+		5) #Google
+		echo 'push "dhcp-option DNS 8.8.8.8"' >> /etc/openvpn/server.conf
+		echo 'push "dhcp-option DNS 8.8.4.4"' >> /etc/openvpn/server.conf
+		;;
+		6) #Yandex Basic
+		echo 'push "dhcp-option DNS 77.88.8.8"' >> /etc/openvpn/server.conf
+		echo 'push "dhcp-option DNS 77.88.8.1"' >> /etc/openvpn/server.conf
+		;;
+		7) #AdGuard DNS
+		echo 'push "dhcp-option DNS 176.103.130.130"' >> /etc/openvpn/server.conf
+		echo 'push "dhcp-option DNS 176.103.130.131"' >> /etc/openvpn/server.conf
+		;;
+	esac
+echo 'push "redirect-gateway def1 bypass-dhcp" '>> /etc/openvpn/server.conf
+echo "crl-verify crl.pem
+ca ca.crt
+cert server.crt
+key server.key
+tls-auth tls-auth.key 0
+dh dh.pem
+auth SHA256
+$CIPHER
+tls-server
+tls-version-min 1.2
+tls-cipher TLS-DHE-RSA-WITH-AES-128-GCM-SHA256
+status openvpn.log
+verb 3" >> /etc/openvpn/server.conf
+
+	# Create the sysctl configuration file if needed (mainly for Arch Linux)
+	if [[ ! -e $SYSCTL ]]; then
+		touch $SYSCTL
+	fi
+
+	# Enable net.ipv4.ip_forward for the system
+	sed -i '/\<net.ipv4.ip_forward\>/c\net.ipv4.ip_forward=1' $SYSCTL
+	if ! grep -q "\<net.ipv4.ip_forward\>" $SYSCTL; then
+		echo 'net.ipv4.ip_forward=1' >> $SYSCTL
+	fi
+	# Avoid an unneeded reboot
+	echo 1 > /proc/sys/net/ipv4/ip_forward
+	# Needed to use rc.local with some systemd distros
+ 	if [[ "$OS" = 'debian' && ! -e $RCLOCAL ]]; then
+ 		echo '#!/bin/sh -e
+ exit 0' > $RCLOCAL
+	fi
+	chmod +x $RCLOCAL
+	# Set NAT for the VPN subnet
+	iptables -t nat -A POSTROUTING -o $NIC -s 10.8.0.0/24 -j MASQUERADE
+	sed -i "1 a\iptables -t nat -A POSTROUTING -o $NIC -s 10.8.0.0/24 -j MASQUERADE" $RCLOCAL
+	if pgrep firewalld; then
+		# We don't use --add-service=openvpn because that would only work with
+		# the default port. Using both permanent and not permanent rules to
+		# avoid a firewalld reload.
+		if [[ "$PROTOCOL" = 'UDP' ]]; then
+			firewall-cmd --zone=public --add-port=$PORT/udp
+			firewall-cmd --permanent --zone=public --add-port=$PORT/udp
+		elif [[ "$PROTOCOL" = 'TCP' ]]; then
+			firewall-cmd --zone=public --add-port=$PORT/tcp
+			firewall-cmd --permanent --zone=public --add-port=$PORT/tcp
+		fi
+		firewall-cmd --zone=trusted --add-source=10.8.0.0/24
+		firewall-cmd --permanent --zone=trusted --add-source=10.8.0.0/24
+	fi
+	if iptables -L -n | grep -qE 'REJECT|DROP'; then
+		# If iptables has at least one REJECT rule, we asume this is needed.
+		# Not the best approach but I can't think of other and this shouldn't
+		# cause problems.
+		if [[ "$PROTOCOL" = 'UDP' ]]; then
+			iptables -I INPUT -p udp --dport $PORT -j ACCEPT
+		elif [[ "$PROTOCOL" = 'TCP' ]]; then
+			iptables -I INPUT -p tcp --dport $PORT -j ACCEPT
+		fi
+		iptables -I FORWARD -s 10.8.0.0/24 -j ACCEPT
+		iptables -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
+		if [[ "$PROTOCOL" = 'UDP' ]]; then
+			sed -i "1 a\iptables -I INPUT -p udp --dport $PORT -j ACCEPT" $RCLOCAL
+		elif [[ "$PROTOCOL" = 'TCP' ]]; then
+			sed -i "1 a\iptables -I INPUT -p tcp --dport $PORT -j ACCEPT" $RCLOCAL
+		fi
+		sed -i "1 a\iptables -I FORWARD -s 10.8.0.0/24 -j ACCEPT" $RCLOCAL
+		sed -i "1 a\iptables -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT" $RCLOCAL
+	fi
+	# If SELinux is enabled and a custom port was selected, we need this
+	if hash sestatus 2>/dev/null; then
+		if sestatus | grep "Current mode" | grep -qs "enforcing"; then
+			if [[ "$PORT" != '1194' ]]; then
+				# semanage isn't available in CentOS 6 by default
+				if ! hash semanage 2>/dev/null; then
+					yum install policycoreutils-python -y
+				fi
+				if [[ "$PROTOCOL" = 'UDP' ]]; then
+					semanage port -a -t openvpn_port_t -p udp $PORT
+				elif [[ "$PROTOCOL" = 'TCP' ]]; then
+					semanage port -a -t openvpn_port_t -p tcp $PORT
+				fi
+			fi
+		fi
+	fi
+	# And finally, restart OpenVPN
+	if [[ "$OS" = 'debian' ]]; then
+		# Little hack to check for systemd
+		if pgrep systemd-journal; then
+			if [[ "$VERSION_ID" = 'VERSION_ID="9"' ]]; then
+				#Workaround to fix OpenVPN service on Debian 9 OpenVZ
+				sed -i 's|LimitNPROC|#LimitNPROC|' /lib/systemd/system/openvpn-server\@.service
+				sed -i 's|/etc/openvpn/server|/etc/openvpn|' /lib/systemd/system/openvpn-server\@.service
+				sed -i 's|%i.conf|server.conf|' /lib/systemd/system/openvpn-server\@.service
+				systemctl daemon-reload
+				systemctl restart openvpn-server@openvpn.service
+				systemctl enable openvpn-server@openvpn.service
+			else
+				systemctl restart openvpn@server.service
+			fi
+		else
+			/etc/init.d/openvpn restart
+		fi
+	else
+		if pgrep systemd-journal; then
+			if [[ "$OS" = 'arch' ]]; then
+				#Workaround to avoid rewriting the entire script for Arch
+				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
+	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=$USEREXTERNALIP
+		fi
+	fi
+	# client-template.txt is created so we have a template to add further users later
+	echo "client" > /etc/openvpn/client-template.txt
+	if [[ "$PROTOCOL" = 'UDP' ]]; then
+		echo "proto udp" >> /etc/openvpn/client-template.txt
+	elif [[ "$PROTOCOL" = 'TCP' ]]; then
+		echo "proto tcp-client" >> /etc/openvpn/client-template.txt
+	fi
+	echo "remote $IP $PORT
+dev tun
+resolv-retry infinite
+nobind
+persist-key
+persist-tun
+remote-cert-tls server
+auth SHA256
+$CIPHER
+tls-client
+tls-version-min 1.2
+tls-cipher TLS-DHE-RSA-WITH-AES-128-GCM-SHA256
+setenv opt block-outside-dns
+verb 3" >> /etc/openvpn/client-template.txt
+
+	# 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!"
+fi
+exit 0;