= openswan (PSK)

                      eth0           eth1
client ---  192.168.1.1 [VPN server] 192.168.0.10  --------   192.168.0.11 [server1]
                                     ppp               |
                                     192.168.0.5       |---   192.168.0.12 [server2]

#apt-get install openswan l2tpd

#vim /etc/ipsec.conf

version 2.0
config setup
        nat_traversal=yes
        nhelpers=0

conn L2TP-PSK
        type=transport
        ike=3des-md5
        esp=3des-md5
        authby=secret
        pfs=no
        rekey=no
        keyingtries=3
        left=%defaultroute
        #leftnexthop=%defaultroute
        leftprotoport=17/1701
        right=%any
        rightprotoport=17/%any
        auto=add

include /etc/ipsec.d/examples/no_oe.conf

#vim /etc/ipsec.secrets

: PSK "1234567890"


#vim /etc/l2tpd/l2tpd.conf

[lns default]
ip range = 192.168.0.50-192.168.0.100
local ip = 192.168.0.5 #  
require chap = yes
refuse pap = yes
require authentication = yes
name = LinuxVPNserver   
ppp debug = yes
pppoptfile = /etc/ppp/options.l2tpd
length bit = yes


#vim /etc/ppp/options.l2tpd

require-mschap-v2
nodefaultroute
debug
lock
nobsdcomp

#vim �B/etc/ppp/chap-secrets

user LinuxVPNserver password *

#sysctl net.ipv4.ip_forward=1
#vim /etc/sysctl.conf
net.ipv4.ip_forward = 1

#/etc/init.d/ipsec restart
#/etc/init.d/l2tpd restart

Windows setting

Create a new connection, type user name and password
Click Proerties, type ip address of server
Click "Security" tab, Click IPSec Settings, and type PSK key.
Click "Networking" tab, Chose "Internet Protocol(TCP/IP), Click "Properties""
Click "Advanced" , uncheck "Usedefault gateway on remote network"
Connect