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setup-ipsec-vpn/vpnsetup.sh
hwdsl2 7cdd372a6e Improve IPTables rules 
- Fixed an uncommon use case where the setup script is run again after
  a server IP change. Make sure to update IPTables rules in this case.
- Thanks @larryisthere! Ref: #17
2016-09-21 21:06:22 -05:00

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#!/bin/sh
#
# Script for automatic setup of an IPsec VPN server on Ubuntu LTS and Debian 8.
# Works on any dedicated server or Virtual Private Server (VPS) except OpenVZ.
#
# DO NOT RUN THIS SCRIPT ON YOUR PC OR MAC! THIS IS MEANT TO BE RUN
# ON A DEDICATED SERVER OR VPS!
#
# Copyright (C) 2014-2016 Lin Song <linsongui@gmail.com>
# Based on the work of Thomas Sarlandie (Copyright 2012)
#
# This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
# Unported License: http://creativecommons.org/licenses/by-sa/3.0/
#
# Attribution required: please include my name in any derivative and let me
# know how you have improved it!
# =====================================================
# Define your own values for these variables
# - IPsec pre-shared key, VPN username and password
# - All values MUST be placed inside 'single quotes'
# - DO NOT use these characters within values: \ " '
YOUR_IPSEC_PSK=''
YOUR_USERNAME=''
YOUR_PASSWORD=''
# Important notes: https://git.io/vpnnotes
# Setup VPN clients: https://git.io/vpnclients
# =====================================================
export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
exiterr() { echo "Error: ${1}" >&2; exit 1; }
exiterr2() { echo "Error: 'apt-get install' failed." >&2; exit 1; }
os_type="$(lsb_release -si 2>/dev/null)"
if [ "$os_type" != "Ubuntu" ] && [ "$os_type" != "Debian" ] && [ "$os_type" != "Raspbian" ]; then
exiterr "This script only supports Ubuntu/Debian."
fi
if [ -f /proc/user_beancounters ]; then
exiterr "This script does not support OpenVZ VPS."
fi
if [ "$(id -u)" != 0 ]; then
exiterr "Script must be run as root. Try 'sudo sh $0'"
fi
eth0_state=$(cat /sys/class/net/eth0/operstate 2>/dev/null)
if [ -z "$eth0_state" ] || [ "$eth0_state" = "down" ]; then
cat 1>&2 <<'EOF'
Error: Network interface 'eth0' is not available.
Please DO NOT run this script on your PC or Mac!
Run 'cat /proc/net/dev' to find the active network interface,
then use it to replace ALL 'eth0' and 'eth+' in this script.
EOF
exit 1
fi
[ -n "$YOUR_IPSEC_PSK" ] && VPN_IPSEC_PSK="$YOUR_IPSEC_PSK"
[ -n "$YOUR_USERNAME" ] && VPN_USER="$YOUR_USERNAME"
[ -n "$YOUR_PASSWORD" ] && VPN_PASSWORD="$YOUR_PASSWORD"
if [ -z "$VPN_IPSEC_PSK" ] && [ -z "$VPN_USER" ] && [ -z "$VPN_PASSWORD" ]; then
echo "VPN credentials not set by user. Generating random PSK and password..."
echo
VPN_IPSEC_PSK="$(LC_CTYPE=C tr -dc 'A-HJ-NPR-Za-km-z2-9' < /dev/urandom | head -c 16)"
VPN_USER=vpnuser
VPN_PASSWORD="$(LC_CTYPE=C tr -dc 'A-HJ-NPR-Za-km-z2-9' < /dev/urandom | head -c 16)"
fi
if [ -z "$VPN_IPSEC_PSK" ] || [ -z "$VPN_USER" ] || [ -z "$VPN_PASSWORD" ]; then
exiterr "All VPN credentials must be specified. Edit the script and re-enter them."
fi
if [ "$(sed 's/\..*//' /etc/debian_version 2>/dev/null)" = "7" ]; then
cat <<'EOF'
IMPORTANT: Workaround required for Debian 7 (Wheezy).
You must first run the script at: https://git.io/vpndeb7
If not already done so, press Ctrl-C to interrupt now.
Continuing in 30 seconds ...
EOF
sleep 30
fi
echo "VPN setup in progress... Please be patient."
echo
# Create and change to working dir
mkdir -p /opt/src
cd /opt/src || exiterr "Cannot enter /opt/src."
# Update package index
export DEBIAN_FRONTEND=noninteractive
apt-get -yq update || exiterr "'apt-get update' failed."
# Make sure basic commands exist
apt-get -yq install wget dnsutils openssl || exiterr2
apt-get -yq install iproute gawk grep sed net-tools || exiterr2
cat <<'EOF'
Trying to auto discover IPs of this server...
In case the script hangs here for more than a few minutes,
use Ctrl-C to interrupt. Then edit it and manually enter IPs.
EOF
# In case auto IP discovery fails, you may manually enter server IPs here.
# If your server only has a public IP, put that public IP on both lines.
PUBLIC_IP=${VPN_PUBLIC_IP:-''}
PRIVATE_IP=${VPN_PRIVATE_IP:-''}
# Try to auto discover IPs of this server
[ -z "$PUBLIC_IP" ] && PUBLIC_IP=$(dig @resolver1.opendns.com -t A -4 myip.opendns.com +short)
[ -z "$PRIVATE_IP" ] && PRIVATE_IP=$(ip -4 route get 1 | awk '{print $NF;exit}')
# Check IPs for correct format
IP_REGEX="^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$"
if ! printf %s "$PUBLIC_IP" | grep -Eq "$IP_REGEX"; then
PUBLIC_IP=$(wget -t 3 -T 15 -qO- http://whatismyip.akamai.com)
fi
if ! printf %s "$PUBLIC_IP" | grep -Eq "$IP_REGEX"; then
PUBLIC_IP=$(wget -t 3 -T 15 -qO- http://ipv4.icanhazip.com)
fi
if ! printf %s "$PUBLIC_IP" | grep -Eq "$IP_REGEX"; then
exiterr "Cannot find valid public IP. Edit the script and manually enter IPs."
fi
if ! printf %s "$PRIVATE_IP" | grep -Eq "$IP_REGEX"; then
PRIVATE_IP=$(ifconfig eth0 | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*')
fi
if ! printf %s "$PRIVATE_IP" | grep -Eq "$IP_REGEX"; then
exiterr "Cannot find valid private IP. Edit the script and manually enter IPs."
fi
# Install necessary packages
apt-get -yq install libnss3-dev libnspr4-dev pkg-config libpam0g-dev \
libcap-ng-dev libcap-ng-utils libselinux1-dev \
libcurl4-nss-dev flex bison gcc make \
libunbound-dev libnss3-tools libevent-dev || exiterr2
apt-get -yq --no-install-recommends install xmlto || exiterr2
apt-get -yq install ppp xl2tpd || exiterr2
# Install Fail2Ban to protect SSH server
apt-get -yq install fail2ban || exiterr2
# Compile and install Libreswan
swan_ver=3.18
swan_file="libreswan-$swan_ver.tar.gz"
swan_url1="https://download.libreswan.org/$swan_file"
swan_url2="https://github.com/libreswan/libreswan/archive/v$swan_ver.tar.gz"
wget -t 3 -T 30 -nv -O "$swan_file" "$swan_url1" || wget -t 3 -T 30 -nv -O "$swan_file" "$swan_url2"
[ "$?" != "0" ] && exiterr "Cannot download Libreswan source."
/bin/rm -rf "/opt/src/libreswan-$swan_ver"
tar xzf "$swan_file" && /bin/rm -f "$swan_file"
cd "libreswan-$swan_ver" || exiterr "Cannot enter Libreswan source dir."
echo "WERROR_CFLAGS =" > Makefile.inc.local
if [ "$(packaging/utils/lswan_detect.sh init)" = "systemd" ]; then
apt-get -yq install libsystemd-dev || exiterr2
fi
make -s programs && make -s install
# Verify the install and clean up
cd /opt/src || exiterr "Cannot enter /opt/src."
/bin/rm -rf "/opt/src/libreswan-$swan_ver"
/usr/local/sbin/ipsec --version 2>/dev/null | grep -qs "$swan_ver"
[ "$?" != "0" ] && exiterr "Libreswan $swan_ver failed to build."
# Create IPsec (Libreswan) config
sys_dt="$(date +%Y-%m-%d-%H:%M:%S)"
/bin/cp -f /etc/ipsec.conf "/etc/ipsec.conf.old-$sys_dt" 2>/dev/null
cat > /etc/ipsec.conf <<EOF
version 2.0
config setup
nat_traversal=yes
virtual_private=%v4:10.0.0.0/8,%v4:192.168.0.0/16,%v4:172.16.0.0/12,%v4:!192.168.42.0/23
protostack=netkey
nhelpers=0
interfaces=%defaultroute
uniqueids=no
conn shared
left=$PRIVATE_IP
leftid=$PUBLIC_IP
right=%any
forceencaps=yes
authby=secret
pfs=no
rekey=no
keyingtries=5
dpddelay=30
dpdtimeout=120
dpdaction=clear
ike=3des-sha1,aes-sha1,aes256-sha2_512,aes256-sha2_256
phase2alg=3des-sha1,aes-sha1,aes256-sha2_512,aes256-sha2_256
sha2-truncbug=yes
conn l2tp-psk
auto=add
leftsubnet=$PRIVATE_IP/32
leftnexthop=%defaultroute
leftprotoport=17/1701
rightprotoport=17/%any
type=transport
auth=esp
also=shared
conn xauth-psk
auto=add
leftsubnet=0.0.0.0/0
rightaddresspool=192.168.43.10-192.168.43.250
modecfgdns1=8.8.8.8
modecfgdns2=8.8.4.4
leftxauthserver=yes
rightxauthclient=yes
leftmodecfgserver=yes
rightmodecfgclient=yes
modecfgpull=yes
xauthby=file
ike-frag=yes
ikev2=never
cisco-unity=yes
also=shared
EOF
# Specify IPsec PSK
/bin/cp -f /etc/ipsec.secrets "/etc/ipsec.secrets.old-$sys_dt" 2>/dev/null
cat > /etc/ipsec.secrets <<EOF
$PUBLIC_IP %any : PSK "$VPN_IPSEC_PSK"
EOF
# Create xl2tpd config
/bin/cp -f /etc/xl2tpd/xl2tpd.conf "/etc/xl2tpd/xl2tpd.conf.old-$sys_dt" 2>/dev/null
cat > /etc/xl2tpd/xl2tpd.conf <<'EOF'
[global]
port = 1701
[lns default]
ip range = 192.168.42.10-192.168.42.250
local ip = 192.168.42.1
require chap = yes
refuse pap = yes
require authentication = yes
name = l2tpd
pppoptfile = /etc/ppp/options.xl2tpd
length bit = yes
EOF
# Set xl2tpd options
/bin/cp -f /etc/ppp/options.xl2tpd "/etc/ppp/options.xl2tpd.old-$sys_dt" 2>/dev/null
cat > /etc/ppp/options.xl2tpd <<'EOF'
ipcp-accept-local
ipcp-accept-remote
ms-dns 8.8.8.8
ms-dns 8.8.4.4
noccp
auth
crtscts
mtu 1280
mru 1280
lock
proxyarp
lcp-echo-failure 4
lcp-echo-interval 30
connect-delay 5000
EOF
# Create VPN credentials
/bin/cp -f /etc/ppp/chap-secrets "/etc/ppp/chap-secrets.old-$sys_dt" 2>/dev/null
cat > /etc/ppp/chap-secrets <<EOF
# Secrets for authentication using CHAP
# client server secret IP addresses
"$VPN_USER" l2tpd "$VPN_PASSWORD" *
EOF
/bin/cp -f /etc/ipsec.d/passwd "/etc/ipsec.d/passwd.old-$sys_dt" 2>/dev/null
VPN_PASSWORD_ENC=$(openssl passwd -1 "$VPN_PASSWORD")
cat > /etc/ipsec.d/passwd <<EOF
$VPN_USER:$VPN_PASSWORD_ENC:xauth-psk
EOF
# Update sysctl settings
if ! grep -qs "hwdsl2 VPN script" /etc/sysctl.conf; then
/bin/cp -f /etc/sysctl.conf "/etc/sysctl.conf.old-$sys_dt" 2>/dev/null
cat >> /etc/sysctl.conf <<'EOF'
# Added by hwdsl2 VPN script
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
net.ipv4.ip_forward = 1
net.ipv4.tcp_syncookies = 1
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.lo.send_redirects = 0
net.ipv4.conf.eth0.send_redirects = 0
net.ipv4.conf.all.rp_filter = 0
net.ipv4.conf.default.rp_filter = 0
net.ipv4.conf.lo.rp_filter = 0
net.ipv4.conf.eth0.rp_filter = 0
net.ipv4.icmp_echo_ignore_broadcasts = 1
net.ipv4.icmp_ignore_bogus_error_responses = 1
net.core.wmem_max = 12582912
net.core.rmem_max = 12582912
net.ipv4.tcp_rmem = 10240 87380 12582912
net.ipv4.tcp_wmem = 10240 87380 12582912
EOF
fi
# Check if IPTables rules need updating
ipt_flag=0
if ! grep -qs "hwdsl2 VPN script" /etc/iptables.rules; then
ipt_flag=1
elif ! iptables -t nat -C POSTROUTING -s 192.168.42.0/24 -o eth+ -j SNAT --to-source "$PRIVATE_IP" 2>/dev/null; then
ipt_flag=1
elif ! iptables -t nat -C POSTROUTING -s 192.168.43.0/24 -o eth+ -m policy --dir out --pol none -j SNAT --to-source "$PRIVATE_IP" 2>/dev/null; then
ipt_flag=1
fi
# Create basic IPTables rules
# - If IPTables is "empty", write out the entire new rule set.
# - If *not* empty, insert only the required rules for the VPN.
if [ "$ipt_flag" = "1" ]; then
service fail2ban stop >/dev/null 2>&1
iptables-save > "/etc/iptables.rules.old-$sys_dt"
sshd_port="$(ss -nlput | grep sshd | awk '{print $5}' | head -n 1 | grep -Eo '[0-9]{1,5}$')"
if [ "$(iptables-save | grep -c '^\-')" = "0" ] && [ "$sshd_port" = "22" ]; then
cat > /etc/iptables.rules <<EOF
# Added by hwdsl2 VPN script
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m conntrack --ctstate INVALID -j DROP
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -d 127.0.0.0/8 -j REJECT
-A INPUT -p icmp -j ACCEPT
-A INPUT -p udp --dport 67:68 --sport 67:68 -j ACCEPT
-A INPUT -p tcp --dport 22 -j ACCEPT
-A INPUT -p udp -m multiport --dports 500,4500 -j ACCEPT
-A INPUT -p udp --dport 1701 -m policy --dir in --pol ipsec -j ACCEPT
-A INPUT -p udp --dport 1701 -j DROP
-A INPUT -j DROP
-A FORWARD -m conntrack --ctstate INVALID -j DROP
# Uncomment to DROP traffic between VPN clients themselves
# -A FORWARD -i ppp+ -o ppp+ -s 192.168.42.0/24 -d 192.168.42.0/24 -j DROP
# -A FORWARD -s 192.168.43.0/24 -d 192.168.43.0/24 -j DROP
-A FORWARD -i eth+ -o ppp+ -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i ppp+ -o eth+ -j ACCEPT
-A FORWARD -i ppp+ -o ppp+ -s 192.168.42.0/24 -d 192.168.42.0/24 -j ACCEPT
-A FORWARD -i eth+ -d 192.168.43.0/24 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -s 192.168.43.0/24 -o eth+ -j ACCEPT
-A FORWARD -j DROP
COMMIT
*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A POSTROUTING -s 192.168.42.0/24 -o eth+ -j SNAT --to-source $PRIVATE_IP
-A POSTROUTING -s 192.168.43.0/24 -o eth+ -m policy --dir out --pol none -j SNAT --to-source $PRIVATE_IP
COMMIT
EOF
else
iptables -I INPUT 1 -p udp -m multiport --dports 500,4500 -j ACCEPT
iptables -I INPUT 2 -p udp --dport 1701 -m policy --dir in --pol ipsec -j ACCEPT
iptables -I INPUT 3 -p udp --dport 1701 -j DROP
iptables -I FORWARD 1 -m conntrack --ctstate INVALID -j DROP
iptables -I FORWARD 2 -i eth+ -o ppp+ -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -I FORWARD 3 -i ppp+ -o eth+ -j ACCEPT
iptables -I FORWARD 4 -i ppp+ -o ppp+ -s 192.168.42.0/24 -d 192.168.42.0/24 -j ACCEPT
iptables -I FORWARD 5 -i eth+ -d 192.168.43.0/24 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -I FORWARD 6 -s 192.168.43.0/24 -o eth+ -j ACCEPT
# Uncomment to DROP traffic between VPN clients themselves
# iptables -I FORWARD 2 -i ppp+ -o ppp+ -s 192.168.42.0/24 -d 192.168.42.0/24 -j DROP
# iptables -I FORWARD 3 -s 192.168.43.0/24 -d 192.168.43.0/24 -j DROP
iptables -A FORWARD -j DROP
iptables -t nat -I POSTROUTING -s 192.168.43.0/24 -o eth+ -m policy --dir out --pol none -j SNAT --to-source "$PRIVATE_IP"
iptables -t nat -I POSTROUTING -s 192.168.42.0/24 -o eth+ -j SNAT --to-source "$PRIVATE_IP"
echo "# Modified by hwdsl2 VPN script" > /etc/iptables.rules
iptables-save >> /etc/iptables.rules
fi
# Update rules for iptables-persistent
if [ -f /etc/iptables/rules.v4 ]; then
/bin/cp -f /etc/iptables/rules.v4 "/etc/iptables/rules.v4.old-$sys_dt"
/bin/cp -f /etc/iptables.rules /etc/iptables/rules.v4
fi
fi
# Load IPTables rules at system boot
mkdir -p /etc/network/if-pre-up.d
cat > /etc/network/if-pre-up.d/iptablesload <<'EOF'
#!/bin/sh
iptables-restore < /etc/iptables.rules
exit 0
EOF
# Start services at boot
if ! grep -qs "hwdsl2 VPN script" /etc/rc.local; then
/bin/cp -f /etc/rc.local "/etc/rc.local.old-$sys_dt" 2>/dev/null
sed --follow-symlinks -i -e '/^exit 0/d' /etc/rc.local
cat >> /etc/rc.local <<'EOF'
# Added by hwdsl2 VPN script
service fail2ban restart || /bin/true
service ipsec start
service xl2tpd start
echo 1 > /proc/sys/net/ipv4/ip_forward
exit 0
EOF
fi
# Reload sysctl.conf
sysctl -e -q -p
# Update file attributes
chmod +x /etc/rc.local
chmod +x /etc/network/if-pre-up.d/iptablesload
chmod 600 /etc/ipsec.secrets* /etc/ppp/chap-secrets* /etc/ipsec.d/passwd*
# Apply new IPTables rules
iptables-restore < /etc/iptables.rules
# Restart services
service fail2ban stop >/dev/null 2>&1
service ipsec stop >/dev/null 2>&1
service xl2tpd stop >/dev/null 2>&1
service fail2ban start
service ipsec start
service xl2tpd start
cat <<EOF
================================================
IPsec VPN server is now ready for use!
Connect to your new VPN with these details:
Server IP: $PUBLIC_IP
IPsec PSK: $VPN_IPSEC_PSK
Username: $VPN_USER
Password: $VPN_PASSWORD
Write these down. You'll need them to connect!
Important notes: https://git.io/vpnnotes
Setup VPN clients: https://git.io/vpnclients
================================================
EOF
exit 0
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