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setup-ipsec-vpn/vpnsetup_centos.sh
hwdsl2 03007079e6 Improve VPN IPs 
- Use %defaultroute and iptables MASQUERADE, no need to detect private IP
- Use %any for the first field of ipsec.secrets, instead of public IP
- As a result, the VPN server should now better adapt to IP changes.
2017-02-10 18:00:29 -06:00

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#!/bin/sh
#
# Script for automatic setup of an IPsec VPN server on CentOS/RHEL 6 and 7.
# Works on any dedicated server or Virtual Private Server (VPS) except OpenVZ.
#
# DO NOT RUN THIS SCRIPT ON YOUR PC OR MAC!
#
# The latest version of this script is available at:
# https://github.com/hwdsl2/setup-ipsec-vpn
#
# Copyright (C) 2015-2017 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"
SYS_DT="$(date +%Y-%m-%d-%H:%M:%S)"; export SYS_DT
exiterr() { echo "Error: $1" >&2; exit 1; }
exiterr2() { echo "Error: 'yum install' failed." >&2; exit 1; }
conf_bk() { /bin/cp -f "$1" "$1.old-$SYS_DT" 2>/dev/null; }
print_status() { echo; echo "## $1"; echo; }
check_ip() {
IP_REGEX="^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$"
printf %s "$1" | tr -d '\n' | grep -Eq "$IP_REGEX"
}
if ! grep -qs -e "release 6" -e "release 7" /etc/redhat-release; then
exiterr "This script only supports CentOS/RHEL 6 and 7."
fi
if [ -f /proc/user_beancounters ]; then
echo "Error: This script does not support OpenVZ VPS." >&2
echo "Try OpenVPN: https://github.com/Nyr/openvpn-install" >&2
exit 1
fi
if [ "$(id -u)" != 0 ]; then
exiterr "Script must be run as root. Try 'sudo sh $0'"
fi
NET_IF0=${VPN_IFACE:-'eth0'}
NET_IFS=${VPN_IFACE:-'eth+'}
if_state=$(cat "/sys/class/net/$NET_IF0/operstate" 2>/dev/null)
if [ -z "$if_state" ] || [ "$if_state" = "down" ] || [ "$NET_IF0" = "lo" ]; then
echo "Error: Network interface '$NET_IF0' is not available." >&2
cat 1>&2 <<'EOF'
DO NOT RUN THIS SCRIPT ON YOUR PC OR MAC!
If running on a server, try this workaround:
VPN_IFACE="$(route | grep '^default' | grep -o '[^ ]*$')"
EOF
cat 1>&2 <<EOF
sudo VPN_IFACE="\$VPN_IFACE" sh "$0"
EOF
exit 1
fi
[ -n "$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
print_status "VPN credentials not set by user. Generating random PSK and password..."
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 "$VPN_PASSWORD" ]; then
exiterr "All VPN credentials must be specified. Edit the script and re-enter them."
fi
case "$VPN_IPSEC_PSK $VPN_USER $VPN_PASSWORD" in
*[\\\"\']*)
exiterr "VPN credentials must not contain any of these characters: \\ \" '"
;;
esac
print_status "VPN setup in progress... Please be patient."
# Create and change to working dir
mkdir -p /opt/src
cd /opt/src || exiterr "Cannot enter /opt/src."
print_status "Installing packages required for setup..."
yum -y install wget bind-utils openssl || exiterr2
yum -y install iproute gawk grep sed net-tools || exiterr2
print_status "Trying to auto discover IP of this server..."
cat <<'EOF'
In case the script hangs here for more than a few minutes,
use Ctrl-C to interrupt. Then edit it and manually enter IP.
EOF
# In case auto IP discovery fails, enter this server's public IP here.
PUBLIC_IP=${VPN_PUBLIC_IP:-''}
# Try to auto discover IP of this server
[ -z "$PUBLIC_IP" ] && PUBLIC_IP=$(dig @resolver1.opendns.com -t A -4 myip.opendns.com +short)
# Check IP for correct format
check_ip "$PUBLIC_IP" || PUBLIC_IP=$(wget -t 3 -T 15 -qO- http://ipv4.icanhazip.com)
check_ip "$PUBLIC_IP" || exiterr "Cannot find valid public IP. Edit the script and manually enter it."
print_status "Adding the EPEL repository..."
yum -y install epel-release || exiterr2
print_status "Installing packages required for the VPN..."
yum -y install nss-devel nspr-devel pkgconfig pam-devel \
libcap-ng-devel libselinux-devel \
curl-devel flex bison gcc make \
fipscheck-devel unbound-devel xmlto || exiterr2
yum -y install ppp xl2tpd || exiterr2
if grep -qs "release 6" /etc/redhat-release; then
yum -y remove libevent-devel
yum -y install libevent2-devel || exiterr2
else
yum -y install libevent-devel systemd-devel || exiterr2
yum -y install iptables-services || exiterr2
fi
print_status "Installing Fail2Ban to protect SSH..."
yum -y install fail2ban || exiterr2
print_status "Compiling and installing Libreswan..."
swan_ver=3.19
swan_file="libreswan-$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"
if ! { wget -t 3 -T 30 -nv -O "$swan_file" "$swan_url1" || wget -t 3 -T 30 -nv -O "$swan_file" "$swan_url2"; }; then
exiterr "Cannot download Libreswan source."
fi
/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
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-$swan_ver"
if ! /usr/local/sbin/ipsec --version 2>/dev/null | grep -qs -F "$swan_ver"; then
exiterr "Libreswan $swan_ver failed to build."
fi
print_status "Creating VPN configuration..."
# Create IPsec (Libreswan) config
conf_bk "/etc/ipsec.conf"
cat > /etc/ipsec.conf <<EOF
version 2.0
config setup
virtual_private=%v4:10.0.0.0/8,%v4:192.168.0.0/16,%v4:172.16.0.0/12,%v4:!192.168.42.0/23
protostack=netkey
nhelpers=0
interfaces=%defaultroute
uniqueids=no
conn shared
left=%defaultroute
leftid=$PUBLIC_IP
right=%any
encapsulation=yes
authby=secret
pfs=no
rekey=no
keyingtries=5
dpddelay=30
dpdtimeout=120
dpdaction=clear
ike=3des-sha1,3des-sha1;modp1024,aes-sha1,aes-sha1;modp1024,aes-sha2,aes-sha2;modp1024
phase2alg=3des-sha1,aes-sha1,aes-sha2
sha2-truncbug=yes
conn l2tp-psk
auto=add
leftprotoport=17/1701
rightprotoport=17/%any
type=transport
phase2=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
conf_bk "/etc/ipsec.secrets"
cat > /etc/ipsec.secrets <<EOF
%any %any : PSK "$VPN_IPSEC_PSK"
EOF
# Create xl2tpd config
conf_bk "/etc/xl2tpd/xl2tpd.conf"
cat > /etc/xl2tpd/xl2tpd.conf <<'EOF'
[global]
port = 1701
[lns default]
ip range = 192.168.42.10-192.168.42.250
local ip = 192.168.42.1
require chap = yes
refuse pap = yes
require authentication = yes
name = l2tpd
pppoptfile = /etc/ppp/options.xl2tpd
length bit = yes
EOF
# Set xl2tpd options
conf_bk "/etc/ppp/options.xl2tpd"
cat > /etc/ppp/options.xl2tpd <<'EOF'
ipcp-accept-local
ipcp-accept-remote
ms-dns 8.8.8.8
ms-dns 8.8.4.4
noccp
auth
mtu 1280
mru 1280
proxyarp
lcp-echo-failure 4
lcp-echo-interval 30
connect-delay 5000
EOF
# Create VPN credentials
conf_bk "/etc/ppp/chap-secrets"
cat > /etc/ppp/chap-secrets <<EOF
# Secrets for authentication using CHAP
# client server secret IP addresses
"$VPN_USER" l2tpd "$VPN_PASSWORD" *
EOF
conf_bk "/etc/ipsec.d/passwd"
VPN_PASSWORD_ENC=$(openssl passwd -1 "$VPN_PASSWORD")
cat > /etc/ipsec.d/passwd <<EOF
$VPN_USER:$VPN_PASSWORD_ENC:xauth-psk
EOF
print_status "Updating sysctl settings..."
if ! grep -qs "hwdsl2 VPN script" /etc/sysctl.conf; then
conf_bk "/etc/sysctl.conf"
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.$NET_IF0.send_redirects = 0
net.ipv4.conf.all.rp_filter = 0
net.ipv4.conf.default.rp_filter = 0
net.ipv4.conf.lo.rp_filter = 0
net.ipv4.conf.$NET_IF0.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
print_status "Updating IPTables rules..."
# Check if IPTables rules need updating
ipt_flag=0
IPT_FILE="/etc/sysconfig/iptables"
if ! grep -qs "hwdsl2 VPN script" "$IPT_FILE" \
|| ! iptables -t nat -C POSTROUTING -s 192.168.42.0/24 -o "$NET_IFS" -j MASQUERADE 2>/dev/null \
|| ! iptables -t nat -C POSTROUTING -s 192.168.43.0/24 -o "$NET_IFS" -m policy --dir out --pol none -j MASQUERADE 2>/dev/null; then
ipt_flag=1
fi
# Add IPTables rules for VPN
if [ "$ipt_flag" = "1" ]; then
service fail2ban stop >/dev/null 2>&1
iptables-save > "$IPT_FILE.old-$SYS_DT"
iptables -I INPUT 1 -m conntrack --ctstate INVALID -j DROP
iptables -I INPUT 2 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -I INPUT 3 -p udp -m multiport --dports 500,4500 -j ACCEPT
iptables -I INPUT 4 -p udp --dport 1701 -m policy --dir in --pol ipsec -j ACCEPT
iptables -I INPUT 5 -p udp --dport 1701 -j DROP
iptables -I FORWARD 1 -m conntrack --ctstate INVALID -j DROP
iptables -I FORWARD 2 -i "$NET_IFS" -o ppp+ -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -I FORWARD 3 -i ppp+ -o "$NET_IFS" -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 "$NET_IFS" -d 192.168.43.0/24 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -I FORWARD 6 -s 192.168.43.0/24 -o "$NET_IFS" -j ACCEPT
# Uncomment if you wish to disallow 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 "$NET_IFS" -m policy --dir out --pol none -j MASQUERADE
iptables -t nat -I POSTROUTING -s 192.168.42.0/24 -o "$NET_IFS" -j MASQUERADE
echo "# Modified by hwdsl2 VPN script" > "$IPT_FILE"
iptables-save >> "$IPT_FILE"
fi
print_status "Creating basic Fail2Ban rules..."
if [ ! -f /etc/fail2ban/jail.local ] ; then
cat > /etc/fail2ban/jail.local <<'EOF'
[ssh-iptables]
enabled = true
filter = sshd
action = iptables[name=SSH, port=ssh, protocol=tcp]
logpath = /var/log/secure
EOF
fi
print_status "Enabling services on boot..."
if grep -qs "release 6" /etc/redhat-release; then
chkconfig iptables on
chkconfig fail2ban on
else
systemctl --now mask firewalld 2>/dev/null
systemctl enable iptables fail2ban 2>/dev/null
fi
if ! grep -qs "hwdsl2 VPN script" /etc/rc.local; then
if [ -f /etc/rc.local ]; then
conf_bk "/etc/rc.local"
else
echo '#!/bin/sh' > /etc/rc.local
fi
cat >> /etc/rc.local <<'EOF'
# Added by hwdsl2 VPN script
modprobe -q pppol2tp
service ipsec restart
service xl2tpd restart
echo 1 > /proc/sys/net/ipv4/ip_forward
EOF
fi
print_status "Starting services..."
# Restore SELinux contexts
restorecon /etc/ipsec.d/*db 2>/dev/null
restorecon /usr/local/sbin -Rv 2>/dev/null
restorecon /usr/local/libexec/ipsec -Rv 2>/dev/null
# Reload sysctl.conf
sysctl -e -q -p
# Update file attributes
chmod +x /etc/rc.local
chmod 600 /etc/ipsec.secrets* /etc/ppp/chap-secrets* /etc/ipsec.d/passwd*
# Apply new IPTables rules
iptables-restore < "$IPT_FILE"
# Restart services
modprobe -q pppol2tp
service fail2ban restart 2>/dev/null
service ipsec restart 2>/dev/null
service xl2tpd restart 2>/dev/null
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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