Overview

Site to Site Configurations are further extension to host to site configurations. Communication is in this case expanded between multiple subnet on both sites of the connection. Subnet and communication IP addresses are defined with leftsourceip, rightsourceip and leftsubnets and rightsubnets.

Site to Site with Pre-shared Key

Required tasks:

1. Prepare both nodes (see: How to Prepare a Nodegrid Node for IPSec)
   
2. 2. On one of the nodes create a Pre-Shared Key (see: How to create Pre-shared Keys for IPSec)
   
3. Create connection configuration file in /etc/ipsec/ipsec.d/ directory as root user
   

Fields	Values	Comments
Connection name	<String>
leftid	@West	Identifier for the west/left site. Values can be: %left  - uses left as value @<STRING> - uses the string The leftid values is used to identify the PSK
left	<IP or FQDN> of the West/Left host	Additional to an actual IP address can the following values be used. These are resolved when the service starts. %defaultgateway %eth0
leftsourceip	<INTERNAL IP TO BE USED>	IP address if the west node which should be used for the tunnel communication. This IP should belong the leftsubnet.
leftsubnet	<SUBNET>	One subnet can be defined
leftsubnets	<LIST OF SUBNETS>	One or multiple subnet can be defined, for each subnet an individual tunnel will be created
rightid	@East	Identifier for the East/right site. Values can be: %right  - uses left as value @<STRING> - uses the string The rightid values is used to identify the PSK
right	<IP or FQDN> of the East/Right host	Additional to an actual IP address can the following values be used. These are resolved when the service starts. %defaultgateway %eth0
rightsourceip	<INTERNAL IP TO BE USED>	IP address if the east node which should be used for the tunnel communication. This IP should belong the rightsubnet.
rightsubnet	< SUBNET>	One subnet can be defined.
rightsubnets	<LIST OF SUBNETS>	One or multiple subnet can be defined, for each subnet a individual tunnel will be created
authby	secret
auto	start	The setting regulates when the IPSec tunnel will be established. Following values are accepted: add (manual start), start (starts with the service), ondemand (will be established if traffic exists), ignore (connection will be ignored and not used)
connaddrfamily	ipv4	Possible values are ipv4 or ipv6

Format:


conn 
     connaddrfamily=ipv4
      auto=
      authby=secret

      leftid=
      left=FQDN>
      leftsourceip=
      leftsubnet=MASK>
      rightid=
      right=FQDN>
      rightsourceip=
      rightsubnets={MASK> MASK>}

Example /etc/ipsec/ipsec.d/site-to-site-psk.conf


conn site-to-site-psk
     connaddrfamily=ipv4
      auto=start
      authby=secret

      leftid=@West
      left=192.168.50.4
      leftsourceip=192.168.59.4
      leftsubnet=192.168.59.0/24
      rightid=@East
      right=192.168.58.4
      rightsourceip=192.168.60.4
      rightsubnets={192.168.60.0/24 192.168.61.0/24}

4. Create a secrets file in /etc/ipsec/ipsec.d/site-to-site-psk.secrets
   

Fields	Values	Comments
leftid	has to match leftid in the connection configuration file	-
rightid	has to match rightid in the connection configuration file	-
PSK	Pre-Shared Key	-

Format:


  : PSK “”

Example for /etc/ipsec/ipsec.d/host-to-host-psk.secrets


@West @East : PSK "z29p/x/g10cI… … … … RafMGnwTH3Bk="

5. Copy the configuration file and the secret file to the other node.
   
6. Restart IPSec service on both nodes
   

root@ng-west:~# ipsec restart
Redirecting to: /etc/init.d/ipsec stop
Shutting down pluto IKE daemon
002 shutting down

Redirecting to: /etc/init.d/ipsec start
Starting pluto IKE daemon for IPsec: .
root@ng-west:~#

7. Confirm that the tunnel was established
   
1. Short Information
   

root@ng-west:~# ipsec whack --trafficstatus
006 #2: "site-to-site-psk", type=ESP, add_time=1524092870, inBytes=0, outBytes=0, id='@East'

2. More Detailed Information
   

root@ng-west:~# ipsec whack --status |grep site-to-site-psk
……………. 
000 #2: "site-to-site-psk":500 STATE_QUICK_I2 (sent QI2, IPsec SA established); EVENT_SA_REPLACE in 27867s; newest IPSEC; eroute owner; isakmp#1; idle; import:admin initiate
000 #2: "site-to-site-psk" esp.f0f258e4@192.168.58.4 esp.6d38b7cc@192.168.50.4 tun.0@192.168.58.4 tun.0@192.168.50.4 ref=0 refhim=0 Traffic: ESPin=0B ESPout=0B! ESPmax=4194303B
000 #1: "site-to-site-psk":500 STATE_MAIN_I4 (ISAKMP SA established); EVENT_SA_REPLACE in 2426s; newest ISAKMP; lastdpd=-1s(seq in:0 out:0); idle; import:admin initiate