Reply To: site to site vpn using ipsec?

[sergej]

My configuration of site-to-site IPsec with PSKs:

Assume network parameters:
My IP (zeroshell site): 120.120.120.120
Remote IP: 100.100.100.100
My LAN (behind zeroshell): 10.0.0.0/16
Remote LAN: 192.168.47.0/24

Config preparation:
mkdir -p /Database/custom/ipsec

Here I made 3 files

psk.txt (with PSKs – preshared keys):

100.100.100.100        Preshared key 1

ipsec.conf (with IPsec policies):

#!/usr/sbin/setkey -f

#

# Flush SAD and SPD

flush;

spdflush;



# Create policies for racoon

spdadd 10.0.0.0/16 192.168.47.0/24 any -P out ipsec

esp/tunnel/120.120.120.120-100.100.100.100/require;



spdadd 192.168.47.0/24 10.0.0.0/16 any -P in ipsec

esp/tunnel/100.100.100.100-120.120.120.120/require;

racoon.conf:

path pre_shared_key "/Database/custom/ipsec/psk.txt";



listen { isakmp 120.120.120.120; }



remote 100.100.100.100 {

exchange_mode main;

proposal {

encryption_algorithm 3des;

hash_algorithm md5;

authentication_method pre_shared_key;

dh_group modp1024;

}

}



sainfo address 10.0.0.0/16 any address 192.168.47.0/24 any {

pfs_group modp1024;

encryption_algorithm 3des;

authentication_algorithm hmac_md5;

compression_algorithm deflate;

}

Start IPsec in zeroshell’s post boot script:

# Start IPsec

iptables -t nat -I POSTROUTING -s 10.0.0.0/16 -d 192.168.47.0/24 -j ACCEPT

setkey -f /Database/custom/ipsec/ipsec.conf

racoon -f /Database/custom/ipsec/racoon.conf

You should allow VPN traffic by firewall rules as well (UDP/500, ESP and site-to-site traffic).