Установка и настройка IPSEC L2TP VPN сервера

yum install epel-release

yum install bind-utils

yum install openswan xl2tpd ppp lsof

rpm -Uvh openswan-2.6.32-16.el6.x86_64.rpm

rpm -Uvh openswan-2.6.32-16.el6.i686.rpm

iptables --table nat --append POSTROUTING --jump MASQUERADE

net.ipv4.ip_forward = 1
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.all.send_redirects = 0

for vpn in /proc/sys/net/ipv4/conf/*; do echo 0 > $vpn/accept_redirects; echo 0 > $vpn/send_redirects; done

sysctl -p

for vpn in /proc/sys/net/ipv4/conf/*; do echo 0 > $vpn/accept_redirects; echo 0 > $vpn/send_redirects; done
iptables -t nat -A POSTROUTING -j SNAT --to-source %SERVERIP%

nano /etc/ipsec.conf

version 2 # conforms to second version of ipsec.conf specification

config setup
    dumpdir=/var/run/pluto/
    #in what directory should things started by setup (notably the Pluto daemon) be allowed to dump core?

    nat_traversal=yes
    #whether to accept/offer to support NAT (NAPT, also known as "IP Masqurade") workaround for IPsec

    virtual_private=%v4:10.0.0.0/8,%v4:192.168.0.0/16,%v4:172.16.0.0/12,%v6:fd00::/8,%v6:fe80::/10
    #contains the networks that are allowed as subnet= for the remote client. In other words, the address ranges that may live behind a NAT router through which a client connects.

    protostack=netkey
    #decide which protocol stack is going to be used.

    force_keepalive=yes
    keep_alive=60
    # Send a keep-alive packet every 60 seconds.

conn L2TP-PSK-noNAT
    authby=secret
    #shared secret. Use rsasig for certificates.

    pfs=no
    #Disable pfs

    auto=add
    #the ipsec tunnel should be started and routes created when the ipsec daemon itself starts.

    keyingtries=3
    #Only negotiate a conn. 3 times.

    ikelifetime=8h
    keylife=1h

    ike=aes256-sha1;modp1024!
    phase2alg=aes256-sha1;modp1024
    # specifies the phase 1 encryption scheme, the hashing algorithm, and the diffie-hellman group. The modp1024 is for Diffie-Hellman 2. Why 'modp' instead of dh? DH2 is a 1028 bit encryption algorithm that modulo's a prime number, e.g. modp1028. See RFC 5114 for details or the wiki page on diffie hellmann, if interested.

    type=transport
    #because we use l2tp as tunnel protocol

    left=%SERVERIP%
    #fill in server IP above

    leftprotoport=17/1701
    right=%any
    rightprotoport=17/%any

    dpddelay=10
    # Dead Peer Dectection (RFC 3706) keepalives delay
    dpdtimeout=20
    #  length of time (in seconds) we will idle without hearing either an R_U_THERE poll from our peer, or an R_U_THERE_ACK reply.
    dpdaction=clear
    # When a DPD enabled peer is declared dead, what action should be taken. clear means the eroute and SA with both be cleared.

%SERVERIP%  %any:   PSK "357xCT1h2QY8+059k2eHZdaL3eogoTM8jHyzCF2kQxr6Zn4+PGmvuEILJMW8fP63"

ipsec verify

Checking your system to see if IPsec got installed and started correctly:
Version check and ipsec on-path                                 [OK]
Linux Openswan U2.6.32/K2.6.32-573.7.1.el6.x86_64 (netkey)
Checking for IPsec support in kernel                            [OK]
 SAref kernel support                                           [N/A]
 NETKEY:  Testing for disabled ICMP send_redirects              [OK]
NETKEY detected, testing for disabled ICMP accept_redirects     [OK]
Checking that pluto is running                                  [OK]
 Pluto listening for IKE on udp 500                             [OK]
 Pluto listening for NAT-T on udp 4500                          [OK]
Two or more interfaces found, checking IP forwarding            [OK]
Checking NAT and MASQUERADEing                                  [OK]
Checking for 'ip' command                                       [OK]
Checking /bin/sh is not /bin/dash                               [WARNING]
Checking for 'iptables' command                                 [OK]
Opportunistic Encryption Support                                [DISABLED]

service ipsec start

[global]
ipsec saref = yes
force userspace = yes

[lns default]
ip range = 10.1.2.1-10.1.2.100
local ip = %IP_ADDRESS%
refuse pap = yes
require authentication = yes
ppp debug = no
pppoptfile = /etc/ppp/options.xl2tpd
length bit = yes

unix authentication = yes

refuse pap = yes

require-mschap-v2

login

auth    required        pam_nologin.so
auth    required        pam_unix.so
account required        pam_unix.so
session required        pam_unix.so

*       l2tpd           ""              *

require-mschap-v2
ms-dns 8.8.8.8
ms-dns 8.8.4.4
auth
mtu 1200
mru 1000
crtscts
hide-password
modem
name l2tpd
proxyarp
lcp-echo-interval 30
lcp-echo-failure 4

# Secrets for authentication using CHAP
# client       server  secret                  IP addresses
robinzon          l2tpd   5H3leJQg3Owu749uwOuwtQ            *
pyatnica            l2tpd   6qkZsl274bEGL8FKvOgA4X3vS0             *

/etc/init.d/ipsec restart
/etc/init.d/xl2tpd restart