How to configure IPSec Host to Site tunnel with Pre-Shared Key

How to configure IPSec Host to Site tunnel with Pre-Shared Key

Version 0.1 (02 May 2018)

Overview

Host to Site configurations are very similar to Host to Host configurations, especially the authentication methods are the same. Added changes to the configurations are the values for rightsourceip and rightsubnets. These values will expose the listed subnets to the IPSec tunnel and will allows clients in these subnets to communicate with the host (west) node and will allow the west node to allow to communicate with clients in the listed subnets.

In case rightsourceip is used the communication between the 2 nodes will not be encrypted only communication between the west node and the subnet would be encrypted. If a value is defined, then all communication between the East and the west host will use the defined IP Address.


Figure 12: Host to Site Configuration Example Details

Host to Site with Pre-shared Key

  1. Prepare both nodes (see: How to Prepare a Nodegrid Node for IPSec)
  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 use
  4. 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
    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.
    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>
          rightid=
          right=FQDN>
          rightsourceip=
          rightsubnet={MASK> MASK>}

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

    conn host-to-site-psk
         connaddrfamily=ipv4
          auto=start
          authby=secret
    
          leftid=@West
          left=192.168.50.4
          rightid=@East
          right=192.168.58.4
          rightsourceip=192.168.60.4
          rightsubnets={192.168.60.0/24 192.168.61.0/24}
  5. Create a secrets file in /etc/ipsec/ipsec.d/host-to-site-psk.secrets
  6. 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-site-psk.secrets

    @West @East : PSK "z29p/x/g10cI… … … … RafMGnwTH3Bk="
  7. Copy the configuration file and the secret file to the other node.
  8. Restart IPSec service on both nodes
  9. 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:~#
  10. Confirm that the tunnel was established
    1. Short information
    2. root@ng-west:~# ipsec whack --trafficstatus
      006 #2: "host-to-site-psk", type=ESP, add_time=1524092870, inBytes=0, outBytes=0, id='@East'
    3. More Detailed information
    4. root@ng-west:~# ipsec whack --status |grep host-to-site-psk
      ……………. 
      000 #2: "host-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: "host-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: "host-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

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