View source for L2TPv3 over IPsec configuration example LV

==Introduction==

<span style="color: red;">The information on this page is updated in accordance with firmware version <span style="color: #0054A6;"><b>00.07.10.4</b></span>.</span>
Due to the inherent lack of confidentiality in the '''Layer 2 Tunneling Protocol''' ('''L2TP'''), it is commonly secured by pairing it with '''Internet Protocol Security''' ('''IPsec'''). IPsec provides essential features such as confidentiality, authentication, and integrity for L2TP packets. This combination is widely referred to as '''L2TP over IPsec''' (or simply '''L2TP/IPsec''') and is a standard approach for secure VPN implementations.

This article provides instructions on configuring L2TPv3 over IPsec on Teltonika routers and gateway devices. Please note that the guide is designed for advanced users and skips some of the more straightforward steps to maintain overall clarity. For instance, adding new instances is only briefly mentioned rather than described in detail. If this level of information feels insufficient for your setup, consider referring to our dedicated configuration guides '''[[IPsec RUTOS configuration example|IPsec]]''' and '''[[L2TP configuration examples RutOS|L2TP]]''' for reference.

==Configuration overview and prerequisites==

Before we begin, let's overview the configuration that we are attempting to achieve and the prerequisites that make it possible.

'''Prerequisites''':
* Two RUTxxx routers
* At least one router with a Public Static or Public Dynamic IP addresses
* At least one end device (PC, Laptop, Tablet, Smartphone) to configure the routers
* Two VLANs configurated on both devices

==Preparation==

As mentioned in Prerequisites, you will need to configure two VLANs on both RUT devices, detailed instructions on how to configure them can be found on this page: '''[[VLAN Set Up]]'''
Everything else we will configure along the way.

===Topology===

[[File:Networking rutxxx configuration examples l2tpv3 over ipsec topology v1.png|border|class=tlt-border|1100px]]

==IPSec configuration==
If you have familiarized yourself with the configuration schemes and have all of the devices in order, we can start configuring the routers using instructions provided in this section.
We will start our configuration with RUT1.

===IPsec RUT1 Config===
----
* Login to the router's WebUI and go to '''Services → VPN -> IPsec'''
* Add a new instance with your desired name, in my case, I will be using '''RUT1'''

[[File:RutOS_IPsec_tunnel_with_certificates_7.8_add_ipsec.png|border|center|class=tlt-border|1102px]]

'''Note:''' ''Not specified fields can be left as is or changed according to your needs.'' 
====Instance configuration====
----
Make the following changes:
# '''''Enable''''' instance;
# Remote endpoint - '''''RUT2 public WAN IP;'''''
# Authentication method - '''''Pre-shared key;'''''
# Pre shared key - '''''Your chosen password (must match for both RUT1 & RUT2)'''''
# Local identifier – '''''RUT1 LAN IP, which is 192.168.3.1 in this case;'''''
# Remote identifier – '''''RUT2 LAN IP, which is 192.168.14.1 in this case;'''''
[[File:RutOS_IPsec_config_ex_7.8_rut1.png|border|class=tlt-border|center]]
====Connection general section configuration====
----
Make the following changes:
# Mode - '''''Start;'''''
# Type - '''''Tunnel;'''''
# Local subnet – '''''192.168.3.0/24;'''''
# Remote subnet – '''''192.168.14.0/24;'''''
# Key exchange - '''''IKEv2;'''''

[[File:RutOS_IPsec_tunnel_with_certificates_7.8_add_ipsec_config_connection.png|border|class=tlt-border|center]]

====Proposal configuration====
'''Important:''' Both the RUT1 and RUT2 Encryptions must match in order for this configuration to work.
----
'''Note:''' ''This is only an example of a secure configuration. Other algorithms or even combinations of them could be used. However, we strongly recommend refraining from using older encryption and hashing algorithms unless support for certain legacy systems is required.''

Make the following changes:
<table class="nd-othertables_2">
    <tr>
        <th width=330; style="border-bottom: 1px solid white;></th>
        <th width=800; style="border-bottom: 1px solid white;" rowspan=2>[[File:Networking_webui_manual_IPsec_configuration_proposal_phase1_settings_v1.png|border|class=tlt-border|671x336px|center]]</th>
    </tr>
    <tr>
        <td style="border-bottom: 4px solid white>
# Encryption - '''''AES256;'''''
# Authentication - '''''SHA512;'''''
# DH group - '''''MODP4096;'''''
# IKE lifetime - '''86400s'''.
        </td>
    </tr>
</table>

----
<table class="nd-othertables_2">
    <tr>
        <th width=330; style="border-bottom: 1px solid white;></th>
        <th width=800; style="border-bottom: 1px solid white;" rowspan=2>[[File:Networking_webui_manual_IPsec_configuration_proposal_phase2_settings_v1.png|border|class=tlt-border|644x331px|center]]</th>
    </tr>
    <tr>
        <td style="border-bottom: 4px solid white>
# Encryption - '''''AES256;'''''
# Authentication - '''''SHA512;'''''
# PFS group - '''''MODP4096;'''''
# Lifetime – '''''86400s;'''''
        </td>
    </tr>
</table>




===IPsec RUT2 Config===
----
* Login to the router's WebUI and go to '''Services → VPN -> IPsec'''
* Add a new instance with your desired name, in my case I will be using '''RUT2'''

[[File:RutOS_IPsec_tunnel_with_certificates_7.8_add_ipsec.png|border|center|class=tlt-border|1102px]]

'''Note:''' ''Not specified fields can be left as is or changed according to your needs.'' 
====Instance configuration====
----
Make the following changes:
# '''''Enable''''' instance;
# Authentication method - '''''Pre-shared key;'''''
# Pre shared key - '''''Your chosen password (must match for both RUT1 & RUT2)'''''
# Local identifier – '''''RUT2 LAN IP, which is 192.168.14.1 in this case;'''''
# Remote identifier – '''''RUT1 LAN IP, which is 192.168.3.1 in this case;'''''
[[File:RutOS_IPsec_config_ex_7.8_rut2222.png|border|class=tlt-border|center]]
====Connection general section configuration====
----
Make the following changes:
# Mode - '''''Start;'''''
# Type - '''''Tunnel;'''''
# Local subnet – '''''192.168.14.0/24;'''''
# Remote subnet – '''''192.168.3.0/24;'''''
# Key exchange - '''''IKEv2;'''''

[[File:RutOS_IPsec_tunnel_with_certificates_7.8_add_ipsec_config_connection_rut2_general.png|border|class=tlt-border|center]]
====Proposal configuration====
'''Important:''' Both the RUT1 and RUT2 Encryptions must match in order for this configuration to work.
----
'''Note:''' ''This is only an example of a secure configuration. Other algorithms or even combinations of them could be used. However, we strongly recommend refraining from using older encryption and hashing algorithms unless support for certain legacy systems is required.''

Make the following changes:
<table class="nd-othertables_2">
    <tr>
        <th width=330; style="border-bottom: 1px solid white;></th>
        <th width=800; style="border-bottom: 1px solid white;" rowspan=2>[[File:Networking_webui_manual_IPsec_configuration_proposal_phase1_settings_v1.png|border|class=tlt-border|671x336px|center]]</th>
    </tr>
    <tr>
        <td style="border-bottom: 4px solid white>
# Encryption - '''''AES256;'''''
# Authentication - '''''SHA512;'''''
# DH group - '''''MODP4096;'''''
# IKE lifetime - '''86400s'''.
        </td>
    </tr>
</table>

----
<table class="nd-othertables_2">
    <tr>
        <th width=330; style="border-bottom: 1px solid white;></th>
        <th width=800; style="border-bottom: 1px solid white;" rowspan=2>[[File:Networking_webui_manual_IPsec_configuration_proposal_phase2_settings_v1.png|border|class=tlt-border|644x331px|center]]</th>
    </tr>
    <tr>
        <td style="border-bottom: 4px solid white>
# Encryption - '''''AES256;'''''
# Authentication - '''''SHA512;'''''
# PFS group - '''''MODP4096;'''''
# Lifetime – '''''86400s;'''''
        </td>
    </tr>
</table>

===Testing IPsec connection===
When you're done with the configuration, you should test whether it works before you move on. The simplest way to test an IPsec connection is using the '''ipsec status''' command. You can execute this command via a command line interface (CLI). A CLI is present in all RUTxxx routers' WebUIs. To access it, login to one of the routers' WebUI (doesn't matter which one) and navigate to '''Services → CLI'''. Log in to CLI with the user name '''root''' and the router's admin password. Then simply the ''ipsec status'' and press the "Enter" key:

[[File:Networking rutxxx configuration examples ipsec status v2.jpg|border|class=tlt-border|1100px]]

As you can see, executing ''ipsec status'' displays the number of active/inactive IPsec connections. If the connection you just configured is the only IPsec connection that you're using, you should a '''1 up''' indication next to Security Associations.

==L2TPv3==

Next, you must configure a working L2TPv3 connection. This subsection contains instructions on how to do just that. The relevant parameters will be encapsulated <span style="color:red">'''in red rectangles'''</span>. Explanations about these parameters will be provided under each example. For more detailed informaton refer to '''[[VPN|VPN, L2TPv3]]'''.

New L2TPv3 instances can be created from the '''Services → VPN → L2TP → L2TPv3''' section of the router's WebUI. Enter a custom name and click the "Add" button to create a new instance. Then click the "Edit" button located next to the newly created instance to enter its configuration page.

===RUT1===

[[File:Networking rutxxx configuration examples l2tpv3 rut1 v1.jpg|border|class=tlt-border|1100px]]

* '''Enable''' - if checked, enables the L2TPv3 instance
* '''Local address''' - IP address of the '''local''' instance. Provide '''RUT1''' device's '''LAN IP''' here.
* '''Tunnel ID''' - Uniquely identifies the tunnel. The value used must match the peer tunnel '''ID''' value being used at the peer. For this example '''3000'''.
* '''Session ID''' - The value used must match the tunnel ID value being used at the peer. For this example '''1000'''.
* '''Peer address''' - IP address of the '''remote''' instance. Provide '''RUT2''' device's '''LAN IP''' here.
* '''Peer Tunnel ID''' - '''RUT2''' Tunnel ID: '''4000'''
* '''Peer Session ID''' - '''RUT2''' Session ID: '''2000'''
* '''Bridge to''' -  you can select an instance that you want to bridge to. In this case select '''None'''.
*'''IPv4 address''' - Provide your '''RUT1''' first '''VLAN IP''' adress here. In this example '''10.10.10.1'''
*'''Netmask''' - netmask for provided IPv4 address above. In this example '''255.255.255.0'''
*'''MTU''' - '''1488'''
*'''Encapsulation''' - '''UDP'''
*'''UDP source port''' - '''RUT1''' UDP port. In this example '''5000'''
*'''UDP destination port''' - '''RUT2''' UDP port. In this example '''6000'''

----


===RUT2===

[[File:Networking rutxxx configuration examples l2tpv3 rut2 v1.jpg|border|class=tlt-border|1100px]]

* '''Enable''' - if checked, enables the L2TPv3 instance
* '''Local address''' - IP address of the '''local''' instance. Provide '''RUT2''' device's '''LAN IP''' here.
* '''Tunnel ID''' - Uniquely identifies the tunnel. The value used must match the peer tunnel '''ID''' value being used at the peer. For this example '''4000'''.
* '''Session ID''' - The value used must match the tunnel ID value being used at the peer. For this example '''2000'''.
* '''Peer address''' - IP address of the '''remote''' instance. Provide '''RUT1''' device's '''LAN IP''' here.
* '''Peer Tunnel ID''' - '''RUT1''' Tunnel ID: '''3000'''
* '''Peer Session ID''' - '''RUT1''' Session ID: '''1000'''
* '''Bridge to''' -  you can select an instance that you want to bridge to. In this case select '''None'''.
*'''IPv4 address''' - Provide your '''RUT2''' first '''VLAN IP''' adress here. In this example '''10.10.10.2'''
*'''Netmask''' - netmask for provided IPv4 address above. In this example '''255.255.255.0'''
*'''MTU''' - '''1488'''
*'''Encapsulation''' - '''UDP'''
*'''UDP source port''' - '''RUT2''' UDP port. In this example '''6000'''
*'''UDP destination port''' - '''RUT1''' UDP port. In this example '''5000'''

----

===Firewall rules===

Before testing L2TPv3 over IPsec configuration we will need to change '''L2TPv3''' Firewall rules on both '''RUT1''' and '''RUT2'''.
To do that Open your device's '''Firewall''' by navigating to '''Network → Firewall → Traffic Rules'''. Now on both '''RUT1''' and '''RUT2''', you will need to find two rules called '''Allow-your_instance_name-L2TPv3-traffic'''

[[File:Networking rutxxx configuration examples l2tpv3 firewall v1.jpg|border|class=tlt-border|1100px]]

Now '''Edit''' both of these rules and search for '''Destination address''' field. In this field, there should be written '''0.0.0.0''' you need to '''delete''' this address and '''Save''' the configuration. Repeat this process on both rules and on both '''RUT1''' and '''RUT2'''.

[[File:Networking rutxxx configuration examples l2tpv3 firewall edit v1.jpg|border|class=tlt-border|1100px]]

----

===Testing L2TPv3 configuration===

The simplest way to test an L2TPv3 connection is using the '''ip l2tp show tunnel''' command. You can execute this command via a command line interface (CLI). A CLI is present in all RUTxxx routers' WebUIs. To access it, login to one of the routers' WebUI (doesn't matter which one) and navigate to '''Services → CLI'''. Log in to CLI with the user name '''root''' and the router's admin password. Then simply the ''ip l2tp show tunnel'' and press the "Enter" key. IF everything was configurated correctly you should see two L2TPv3 tunnels (example was taken from '''RUT1'''):

[[File:Networking rutxxx configuration examples l2tpv3 tunnel status v1.jpg.jpg|border|class=tlt-border|1100px]]

==Testing full configuration==

===TCP Dump===

The first way of testing our setup would be to check if the traffic between '''RUT1''' and '''RUT2''' devices is encrypted. To do this we will require to utilize '''TCP Dump''', '''TCP Dump''' will let us capture traffic that goes through '''RUT2'''. In this example, we will install '''TCP Dump''' on '''RUT2''' and we will proceed on capturing the data that is going through the device.
----

====Installing TCP Dump on RUT2====

Firstly, you will need to connect to the '''RUT2''' device's '''CLI/SSH'''. You can connect the '''RUT2''' device CLI via WebUI by navigating to '''Services → CLI'''. Log in to '''CLI''' with the user name '''root''' and the router's admin password.

Now execute these commands one at a time:



''opkg update''

''opkg install tcpdump''



To test if TCP Dump has been installed on your device execute the command ''tcpdump''

----

====Installing Wireshark====

To see captured data via TCP Dumb we will be using Wireshark, although the data can be seen directly from CLI/SSH, Wireshark will let you see more information about captured data and it is simpler to understand TCP Dump output. The Wireshark can be downloaded [https://www.wireshark.org/#download here].

----

====Capturing TCP Dump====


Now you will need to login on to both '''RUT1''' and '''RUT2''' devices CLI/SSH.
Once you have logged on both devices CLI/SSH, on '''RUT1''' execute command '''ping 10.2.0.0'''

Leave this command running, the output should be similar:

[[File:Networking rutxxx configuration examples l2tpv3 ping rut2 lan v1.jpg|border|class=tlt-border|1100px]]

----
Now on RUT2 execute the command '''tcpdump -i wwan0 -n -w test.pcap''' this command will capture all '''wwan0 interface (mobile)''' traffic and write it into '''test.pcap''' file. Leave this command running for a minute and after that press '''Ctrl + C''' to stop this command.

[[File:Networking rutxxx configuration examples l2tpv3 tcpdump rut2 v1.jpg|border|class=tlt-border|1100px]]

Now in your device (at the directory in that you have executed the TCP Dump command(in this example /root/) you will be able to find '''test.pcap''' file, extract it to your computer(you can find instructions on how to do that here:[[Upload & Download Files from RutOS|'''Upload & Download Files from RutOS''']] and open this file with Wireshark. You should see similar output:

[[File:Networking rutxxx configuration examples l2tpv3 wireshark rut2 v1.jpg|border|class=tlt-border|1100px]]

Here you will need to look if your devices communicate with '''ESP(Encapsulating Security Payload)''' protocol, if so then your configuration is working. 

----

===Ping VLANs===
Another simple method to check if the configuration is working is to test if '''RUT1 VLAN''' can reach '''RUT2 VLAN''' and vice versa. In this example we will execute ping command of '''VLAN1''' interface of '''RUT1''' to '''VLAN1''' of '''RUT2'''.

Once again login to RUT1 CLI/SSH and execute the command '''ping -I 10.10.10.1 10.10.10.2''' this will execute a ping from '''VLAN1 of RUT1 to VLAN1 of RUT2'''. If the configuration is working you should see a similar output of this command:

[[File:Networking rutxxx configuration examples l2tpv3 ping VLANS v1.jpg|border|class=tlt-border|1100px]]

==See also==

Other types of VPNs supported by RUTxxx devices:
*[[L2TP configuration examples RutOS|L2TP configuration examples]]
*[[L2TP over IPsec RutOS|L2TP over IPsec]]
*[[IPsec RUTOS configuration example|IPsec configuration examples]]
*[[GRE Tunnel configuration examples RutOS|GRE Tunnel configuration examples]]
*[[OpenVPN configuration examples RUT R 00.07|OpenVPN configuration examples]]
*[[PPTP configuration examples RutOS|PPTP configuration examples]]
[[Category:Use cases]]