#!/bin/bash
# OpenVPN road warrior installer for Debian, Ubuntu and CentOS
# This script will work on Debian, Ubuntu, CentOS and probably other distros
# of the same families, although no support is offered for them. It isn't
# bulletproof but it will probably work if you simply want to setup a VPN on
# your Debian/Ubuntu/CentOS box. It has been designed to be as unobtrusive and
# universal as possible.
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/TAP 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
RCLOCAL='/etc/rc.local'
elif [[ -e /etc/centos-release || -e /etc/redhat-release ]]; then
OS=centos
RCLOCAL='/etc/rc.d/rc.local'
# Needed for CentOS 7
chmod +x /etc/rc.d/rc.local
else
echo "Looks like you aren't running this installer on a Debian, Ubuntu or CentOS system"
exit 4
fi
newclient () {
# Generates the custom client.ovpn
cp /etc/openvpn/client-common.txt ~/$1.ovpn
echo "" >> ~/$1.ovpn
cat /etc/openvpn/easy-rsa/pki/ca.crt >> ~/$1.ovpn
echo "" >> ~/$1.ovpn
echo "" >> ~/$1.ovpn
cat /etc/openvpn/easy-rsa/pki/issued/$1.crt >> ~/$1.ovpn
echo "" >> ~/$1.ovpn
echo "" >> ~/$1.ovpn
cat /etc/openvpn/easy-rsa/pki/private/$1.key >> ~/$1.ovpn
echo "" >> ~/$1.ovpn
}
# Try to get our IP from the system and fallback to the Internet.
# I do this to make the script compatible with NATed servers (lowendspirit.com)
# and to avoid getting an IPv6.
IP=$(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
if [[ -e /etc/openvpn/server.conf ]]; then
while :
do
clear
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 $CLIENT added, certs available at ~/$CLIENT.ovpn"
exit
;;
2)
# This option could be documented a bit better and maybe even be simplimplified
# ...but what can I say, I want some sleep too
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 $CLIENT
./easyrsa gen-crl
rm -rf pki/reqs/$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
echo ""
echo "Certificate for client $CLIENT revoked"
exit
;;
3)
echo ""
read -p "Do you really want to remove OpenVPN? [y/n]: " -e -i n REMOVE
if [[ "$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 | 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' $RCLOCAL
if which sestatus; then
if sestatus | grep "Current mode" | grep -qs "enforcing"; then
if [[ "$PORT" != '1194' ]]; then
semanage port -d -t openvpn_port_t -p udp $PORT
fi
fi
fi
if [[ "$OS" = 'debian' ]]; then
apt-get remove --purge -y openvpn openvpn-blacklist
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 this quick OpenVPN "road warrior" installer'
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 "First I need to know the IPv4 address of the network interface you want OpenVPN"
echo "listening to."
read -p "IP address: " -e -i $IP IP
echo ""
echo "What port do you want for OpenVPN?"
read -p "Port: " -e -i 1194 PORT
echo ""
echo "What DNS do you want to use with the VPN?"
echo " 1) Current system resolvers"
echo " 2) FDN (recommended)"
echo " 3) OpenDNS"
echo " 4) NTT"
echo " 5) Google"
echo " 6) Hurricane Electric"
read -p "DNS [1-6]: " -e -i 2 DNS
echo ""
echo "Finally, tell me your name for the client cert"
echo "Please, use one word only, no special characters"
read -p "Client name: " -e -i client CLIENT
echo ""
echo "Okay, that was all I needed. We are ready to setup your OpenVPN server now"
read -n1 -r -p "Press any key to continue..."
if [[ "$OS" = 'debian' ]]; then
apt-get update
apt-get install openvpn iptables openssl ca-certificates -y
else
# Else, the distro is CentOS
yum install epel-release -y
yum install openvpn iptables openssl wget ca-certificates which -y
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-3.0.1.tgz https://github.com/OpenVPN/easy-rsa/releases/download/3.0.1/EasyRSA-3.0.1.tgz
tar xzf ~/EasyRSA-3.0.1.tgz -C ~/
mv ~/EasyRSA-3.0.1/ /etc/openvpn/
mv /etc/openvpn/EasyRSA-3.0.1/ /etc/openvpn/easy-rsa/
chown -R root:root /etc/openvpn/easy-rsa/
rm -rf ~/EasyRSA-3.0.1.tgz
cd /etc/openvpn/easy-rsa/
#Use 4096 bits DH instead of 2048 bits
echo "set_var EASYRSA_KEY_SIZE 4096" > vars
# Create the PKI, set up the CA, the DH params and the server + client certificates
./easyrsa init-pki
./easyrsa --batch build-ca nopass
./easyrsa gen-dh
./easyrsa build-server-full server nopass
./easyrsa build-client-full $CLIENT nopass
./easyrsa gen-crl
# Move the stuff we need
cp pki/ca.crt pki/private/ca.key pki/dh.pem pki/issued/server.crt pki/private/server.key /etc/openvpn/easy-rsa/pki/crl.pem /etc/openvpn
# Generate server.conf
echo "port $PORT
proto udp
dev tun
sndbuf 0
rcvbuf 0
ca ca.crt
cert server.crt
key server.key
dh dh.pem
cipher AES-256-CBC
topology subnet
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt" > /etc/openvpn/server.conf
echo 'push "redirect-gateway def1 bypass-dhcp"' >> /etc/openvpn/server.conf
# DNS
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 $line\"" >> /etc/openvpn/server.conf
done
;;
2)
echo 'push "dhcp-option DNS 80.67.169.12"' >> /etc/openvpn/server.conf
echo 'push "dhcp-option DNS 80.67.169.40"' >> /etc/openvpn/server.conf
;;
3)
echo 'push "dhcp-option DNS 208.67.222.222"' >> /etc/openvpn/server.conf
echo 'push "dhcp-option DNS 208.67.220.220"' >> /etc/openvpn/server.conf
;;
4)
echo 'push "dhcp-option DNS 129.250.35.250"' >> /etc/openvpn/server.conf
echo 'push "dhcp-option DNS 129.250.35.251"' >> /etc/openvpn/server.conf
;;
5)
echo 'push "dhcp-option DNS 8.8.8.8"' >> /etc/openvpn/server.conf
echo 'push "dhcp-option DNS 8.8.4.4"' >> /etc/openvpn/server.conf
;;
6)
echo 'push "dhcp-option DNS 74.82.42.42"' >> /etc/openvpn/server.conf
;;
esac
echo "keepalive 10 120
comp-lzo
persist-key
persist-tun
crl-verify crl.pem" >> /etc/openvpn/server.conf
# Enable net.ipv4.ip_forward for the system
if [[ "$OS" = 'debian' ]]; then
sed -i 's|#net.ipv4.ip_forward=1|net.ipv4.ip_forward=1|' /etc/sysctl.conf
else
# CentOS 5 and 6
sed -i 's|net.ipv4.ip_forward = 0|net.ipv4.ip_forward = 1|' /etc/sysctl.conf
# CentOS 7
if ! grep -q "net.ipv4.ip_forward=1" "/etc/sysctl.conf"; then
echo 'net.ipv4.ip_forward=1' >> /etc/sysctl.conf
fi
fi
# Avoid an unneeded reboot
echo 1 > /proc/sys/net/ipv4/ip_forward
# Set NAT for the VPN subnet
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -j SNAT --to $IP
sed -i "1 a\iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -j SNAT --to $IP" $RCLOCAL
if pgrep firewalld; then
# We don't use --add-service=openvpn because that would only work with
# the default port. Using both permanent and not permanent rules to
# avoid a firewalld reload.
firewall-cmd --zone=public --add-port=$PORT/udp
firewall-cmd --zone=trusted --add-source=10.8.0.0/24
firewall-cmd --permanent --zone=public --add-port=$PORT/udp
firewall-cmd --permanent --zone=trusted --add-source=10.8.0.0/24
fi
if iptables -L | 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.
iptables -I INPUT -p udp --dport $PORT -j ACCEPT
iptables -I FORWARD -s 10.8.0.0/24 -j ACCEPT
iptables -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
sed -i "1 a\iptables -I INPUT -p udp --dport $PORT -j ACCEPT" $RCLOCAL
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" $RCLOCAL
fi
# If SELinux is enabled and a custom port was selected, we need this
if which sestatus; then
if sestatus | grep "Current mode" | grep -qs "enforcing"; then
if [[ "$PORT" != '1194' ]]; then
# semanage isn't available in CentOS 6 by default
if ! which semanage > /dev/null 2>&1; then
yum install policycoreutils-python -y
fi
semanage port -a -t openvpn_port_t -p udp $PORT
fi
fi
fi
# And finally, restart OpenVPN
if [[ "$OS" = 'debian' ]]; then
# Little hack to check for systemd
if pgrep systemd-journal; then
systemctl restart openvpn@server.service
else
/etc/init.d/openvpn restart
fi
else
if pgrep systemd-journal; then
systemctl restart openvpn@server.service
systemctl enable openvpn@server.service
else
service openvpn restart
chkconfig openvpn on
fi
fi
# Try to detect a NATed connection and ask about it to potential LowEndSpirit users
EXTERNALIP=$(wget -qO- ipv4.icanhazip.com)
if [[ "$IP" != "$EXTERNALIP" ]]; then
echo ""
echo "Looks like your server is behind a NAT!"
echo ""
echo "If your server is NATed (LowEndSpirit), I need to know the external IP"
echo "If that's not the case, just ignore this and leave the next field blank"
read -p "External IP: " -e USEREXTERNALIP
if [[ "$USEREXTERNALIP" != "" ]]; then
IP=$USEREXTERNALIP
fi
fi
# client-common.txt is created so we have a template to add further users later
echo "client
dev tun
proto udp
sndbuf 0
rcvbuf 0
remote $IP $PORT
resolv-retry infinite
nobind
persist-key
persist-tun
remote-cert-tls server
cipher AES-256-CBC
comp-lzo" > /etc/openvpn/client-common.txt
# Generates the custom client.ovpn
newclient "$CLIENT"
echo ""
echo "Finished!"
echo ""
echo "Your client config is available at ~/$CLIENT.ovpn"
echo "If you want to add more clients, you simply need to run this script another time!"
fi