This document describes how to manually set up a VPN site-to-site connection between two LANCOM routers, i.e. without using the Setup Wizard. The VPN connection is to be established in the aggressive mode.

In aggressive mode, the authentication of a connection does not rely upon public IP addresses, but instead is based upon identities.

These identities are defined for both sides in advanced. Only one public IP address is required as a gateway for setting up the VPN connection.

Another way to configure a site-to-site VPN connection based on just one public IP address is to configure a main-mode connection based on Dynamic VPN.

In 2019 the IETF (Internet Engineering Task Force) has designated IKEv1 as deprecated and insecure and therefore it should not be used anymore. LANCOM Systems instead recommends to use the current standard IKEv2. The IKEv1 functionality in LANCOM devices remains intact and can still be used for scenarios where devices without IKEv2 support are used. However LANCOM Systems will not provide any support regarding the troubleshooting of connection problems with IKEv1 connections. Also there won't be any bug fixes or new features for IKEv1. In rare cases a disconnect can occur during rekeying. In such a case it can be useful to increase the lifetimes, so that the disconnects occur less often.

Requirements:

• LCOS as of version 7 (download latest version)
• LANtools as of version 7 (download latest version)

Scenario:

• A company wishes to interconnect the local networks at their headquarters and at a branch office by means of a site-to-site VPN connection.
• Both sites have a LANCOM router as their gateway and an Internet connection. The fixed public IP address of the headquarters is 80.80.80.80. The public IP address of the branch office is assigned dynamically and changes daily after the forced re-connect by the provider. Because the device at the headquarters has a fixed public IP address, the VPN connection is established from the branch office to the headquarters.
• The local network at the headquarters has the IP address range 192.168.1.0/24, and the branch office uses the local IP address range 192.168.2.0/24.

1.1) Open the configuration for the LANCOM router at the headquarters and switch to the menu item VPN → IKE/IPSec.

1.2) Click the IKE proposal lists button.

1.3) Create a new IKE proposal list. Name it OFFICE and fill out the proposal list with the IKE proposals that should be used. You can enter one or several IKE proposals.

Note:

• From the list of proposals, the first IKE proposal that matches at both ends of the VPN connection is used to establish the IKE Phase 1.

1.4) Click the IPSec proposal lists button.

1.5) Create a new IPSec proposal list. Name it OFFICE and fill out the proposal list with the IPSec proposals that should be used. You can enter one or several IPSec proposals.

Note:

• From the list of proposals, the first IPSec proposal that matches at both ends of the VPN connection is used to establish the IPSec Phase 2.

1.6) Click the IKE keys and identities button.

1.7) Create a new entry. Enter the identification OFFICE and, in the preshared key box, enter a sufficiently secure password.

1.8) Set values for the identity and identity type for the options Local & Remote identity type.

In this example, we will set the local and remote identity to the domain name of the company, company.com.

1.9) Switch to the menu VPN-> General.

• Enable the VPN feature of the LANCOM router.
• Set the option Establ. of net relationships (SAs) to the value Collectively with KeepAlive.

1.10) Then click the Connection parameters button.

1.11) Add a new entry. Enter the identification OFFICE and select the entries of the same name for the IKE proposals, IKE key and IPSec proposals.

The PFS and IKE groups in this example are each set to the default group 2 (MODP-1024). You can change these value to suit your needs. However, make sure that both ends of the VPN connection are set with the same PFS and IKE groups.

1.12) Click the Connection list button.

1.13) Add a new entry. Set the name to OFFICE and select the values for the fields as follows:

• The LANCOM router at the headquarters will be accepting the VPN connection, so the value for the short-hold time must be set to 0 seconds here.
• The Dead Peer Detection is used for monitoring the VPN connection. Enter the value of 60 seconds here. For more information about the Dead Peer Detection, see this Knowledge Base article.
• No entry is required in the field for the remote Gateway.
• Set the Connection parameters to OFFICE.
• The Rule creation is carried out automatically in this example.
  Using this method, the LANCOM router sets up the network relationships between the IP networks that are set to network type INTRANET under IPv4 -> General -> IP networks and the IP networks that are to be found under IP router → Routing → IPv4 routing table behind the corresponding VPN remote station.
• The IKE exchange mode needs to be set to the option Aggressive mode.

1.14) Navigate to the menu IP router → Routing → IPv4 routing table.

1.15) Add a new routing entry.

• As the IP address, enter the address of the local network at the branch office. In this example it is 192.168.2.0.
• The netmask needs to be set to the value 255.255.255.0 as the local network at the branch office is a class C network.
• For the Router field, select the identification of the VPN remote station (in this case: OFFICE).

1.16) Write the configuration back to the LANCOM router.

2.1) Open the configuration for the LANCOM router at the branch office and switch to the menu item VPN → IKE/IPSec.

2.2) Click the IKE proposal lists button.

2.3) Create a new IKE proposal list. Name it HEADQUARTERS and fill out the proposal list with the IKE proposals that should be used. You can enter one or several IKE proposals.

Note:

• Make sure that the same IKE proposals are entered into this list as those used by the LANCOM router at the headquarters (see step 1.3).

2.4) Click the IPSec proposal lists button.

2.5) Create a new IPSec proposal list. Name it HEADQUARTERS and fill out the proposal list with the IPSec proposals that should be used. You can enter one or several IPSec proposals.

Note:

• Make sure that the same IPSec proposals are entered into this list as those used by the LANCOM router at the headquarters (see step 1.5).

2.6) Click the IKE keys and identities button.

2.7) Create a new entry. Set the identification to HEADQUARTERS and enter the same password into the Preshared key field as that used by the LANCOM router at the headquarters (see step 1.7).

2.8) For the options of Local & Remote identity type, set values for the identity and identity type.

In this example, we will set the local and remote identity to the domain name of the company, company.com.

2.9) Switch to the menu VPN → General.

• Enable the VPN feature of the LANCOM router.
• Set the option Establ. of net relationships (SAs) to the value Collectively with KeepAlive.

2.10) Then click the Connection parameters button.

2.11) Add a new entry. Enter the identification HEADQUARTERS and select the entries of the same name for the IKE proposals, IKE key and IPSec proposals.

The PFS and IKE groups in this example are each set to the default group 2 (MODP-1024). You can change these value to suit your needs. However, make sure that both ends of the VPN connection are set with the same PFS and IKE groups.

2.12) Click the Connection list button.

2.13) Add a new entry. Set the name to HEADQUARTERS and select the values for the fields as follows:

• The LANCOM router at the branch office will be actively establishing the VPN connection to the headquarters, so the value for the short-hold time must be set to 9999 seconds here.
• The Dead Peer Detection is used for monitoring the VPN connection. Enter the value of 60 seconds here.
• In the field for the remote Gateway, you need to enter the public IP address of the LANCOM router at the headquarters. In this example it is 80.80.80.80.
• Set the Connection parameters to HEADQUARTERS.
• The Rule creation is carried out automatically in this example.
  Using this method, the LANCOM router sets up the network relationships between the IP networks that are set to network type INTRANET under IPv4 -> General -> IP networks and the IP networks that are to be found under IP router → Routing → IPv4 routing table behind the corresponding VPN remote station.
• The IKE exchange mode needs to be set to the option Aggressive mode.

2.14) Navigate to the menu IP router → Routing → IPv4 routing table.

2.15) Add a new routing entry.

• As the IP address, enter the address of the local network at the headquarters. In this example it is 192.168.1.0.
• The netmask needs to be set to the value 255.255.255.0 as the local network at the headquarters is a class C network.
• For the Router field, select the identification of the VPN remote station (in this case: HEADQUARTERS).

2.16) Write the configuration back to the LANCOM router.

After the configuration has been written back to the LANCOM router at the branch office, the VPN connection can be established between the two LANCOM routers. You can check this for example by loading the two LANCOM routers into the LANmonitor.