Installing vpn on GCE
#!/bin/sh
#
# Automatic configuration of a VPN on GCE debian-7-wheezy server.
# Tested only on debian-7-wheezy.
#
# This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
# Unported License: http://creativecommons.org/licenses/by-sa/3.0/
#
# Thx to: https://github.com/sarfata/voodooprivacy/blob/master/voodoo-vpn.sh for the code/idea
#
# TODO:
IPSEC_PSK=YOUR-KEY
VPN_USER=yourName
VPN_PASSWORD=yourPASSWORD
# Get the 2 ips from: https://console.developers.google.com and click on your instance
PRIVATE_IP=YOUR_PRIVATE_IP
PUBLIC_IP=YOUR_PUBLIC_IP
# start with the basic and install openswan
apt-get install -y openswan xl2tpd
cat > /etc/ipsec.conf <<EOF
version 2.0
config setup
dumpdir=/var/run/pluto/
nat_traversal=yes
virtual_private=%v4:10.0.0.0/8,%v4:192.168.0.0/16,%v4:172.16.0.0/12,%v4:25.0.0.0/8,%v6:fd00::/8,%v6:fe80::/10
oe=off
protostack=netkey
nhelpers=0
interfaces=%defaultroute
conn vpnpsk
auto=add
left=$PRIVATE_IP
leftid=$PUBLIC_IP
leftsubnet=$PRIVATE_IP/32
leftnexthop=%defaultroute
leftprotoport=17/1701
rightprotoport=17/%any
right=%any
rightsubnetwithin=0.0.0.0/0
forceencaps=yes
authby=secret
pfs=no
type=transport
auth=esp
ike=3des-sha1
phase2alg=3des-sha1
dpddelay=30
dpdtimeout=120
dpdaction=clear
EOF
cat > /etc/ipsec.secrets <<EOF
$PUBLIC_IP %any : PSK "$IPSEC_PSK"
EOF
cat > /etc/xl2tpd/xl2tpd.conf <<EOF
[global]
port = 1701
;debug avp = yes
;debug network = yes
;debug state = yes
;debug tunnel = yes
[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
;ppp debug = yes
pppoptfile = /etc/ppp/options.xl2tpd
length bit = yes
EOF
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
idle 1800
mtu 1280
mru 1280
lock
connect-delay 5000
EOF
cat > /etc/ppp/chap-secrets <<EOF
# Secrets for authentication using CHAP
# client server secret IP addresses
$VPN_USER l2tpd $VPN_PASSWORD *
EOF
iptables -t nat -A POSTROUTING -s 192.168.42.0/24 -o eth0 -j MASQUERADE
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables-save > /etc/iptables.rules
cat > /etc/network/if-pre-up.d/iptablesload <<EOF
#!/bin/sh
iptables-restore < /etc/iptables.rules
echo 1 > /proc/sys/net/ipv4/ip_forward
exit 0
EOF
chmod a+x /etc/network/if-pre-up.d/iptablesload
/etc/init.d/ipsec restart
/etc/init.d/xl2tpd restart