instaVPN

vpn.sh

#!/bin/bash

# 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


OS=centos
RCLOCAL='/etc/rc.d/rc.local'
SYSCTL='/etc/sysctl.conf'
# Needed for CentOS 7
chmod +x /etc/rc.d/rc.local


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)

# Get Internet network interface with default route
NIC=$(ip -4 route ls | grep default | grep -Po '(?<=dev )(\S+)')

	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."
	echo ""
	echo "What port do you want for OpenVPN?"
	PORT=1194
	echo ""
	echo "What protocol do you want for OpenVPN?"
	echo "Unless UDP is blocked, you should not use TCP (unnecessarily slower)"
	PROTOCOL=UDP
	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)"
	DNS=4
	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"
	
		CIPHER="cipher AES-128-CBC"

	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)"

		DH_KEY_SIZE="2048"

	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)"

		RSA_KEY_SIZE="2048"

	echo ""
	echo "Finally, tell me a name for the client certificate and configuration"
	CLIENT=client
	echo ""
	echo "Okay, that was all I needed. We are ready to setup your OpenVPN server now"

	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
	IP=$(wget -qO- ipv4.icanhazip.com)

	# 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!"