L2tp ipsec клиент для linux

How to Setup an L2TP/IPsec VPN Client on Linux

L2TP (which stands for Layer 2 Tunneling Protocol) is a tunneling protocol designed to support virtual private networks (VPN connections) over the internet. It is implemented in most if not all modern operating systems including Linux and VPN-capable devices.

The L2TP does not provide any authentication or encryption mechanisms directly to traffic that passes through it, it is usually implemented with the IPsec authentication suite (L2TP/IPsec) to provide encryption within the L2TP tunnel.

In this article, we will show how to set up an L2TP/IPSec VPN connection in Ubuntu and its derivatives and Fedora Linux.

This guide assumes that the L2TP/IPsec VPN server has been set up and that you have received the following VPN connection details from your organization’s or company’s system administrator.

How to Setup L2TP VPN Connection in Linux

To add an L2TP/IPsec option to the NetworkManager, you need to install the NetworkManager-l2tp VPN plugin which supports NetworkManager 1.8 and later. It provides support for L2TP and L2TP/IPsec.

To install the L2TP module on Ubuntu and Ubuntu-based Linux distributions, use the following PPA.

On RHEL/CentOS and Fedora Linux, use the following dnf command to install L2TP module.

Once the package installation is complete, click on your Network Manager icon, then go to Network Settings.

Access Network Settings

Next, add a new VPN connection by clicking on the (+) sign.

Add New VPN Connection

Then select Layer 2 Tunneling Protocol (L2TP) option from the pop-up window.

Select Layer 2 Tunneling Protocol

Next, enter the VPN connection details (gateway IP address or hostname, username and password) you received from the system administrator, in the following window.

Add VPN Details

Next, click IPsec Settings to enter the pre-shared key for the connection. Then enable IPsec tunnel to L2TP host, enter (or copy and paste the) the Pre-shared key and click Ok.

Add Pre-shared Key

After that, click Add. Now your new VPN connection should be added.

VPN Connection Created

Next, turn on the VPN connection to start using it. If the connection details are correct, the connection should be established successfully.

Enable VPN Connection Enabled VPN Connection

Last but not least, test if the VPN is working fine. You can check your computer’s public IP address to confirm this from a web browser: it should now point to the IP of the gateway.

Confirm Your VPN Connection

That’s the end of this article. If you have any queries or thoughts to share, reach us via the feedback form below.

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L2tp ipsec клиент для linux

Configure a Linux VPN client using the command line.

You need the following:

1. VPN Server Address
2. Pre Shared Key
3. Username
4. Password

Install the following packages:

Replace the file content with the following (replace n.n.n.n with your VPN Server Address):

Replace the file content with the following (replace your_pre_shared_key with your PSK value):

Additionaly, run the following only if you are using CentOS/RHEL or Fedora:

Append the following to the file (replace n.n.n.n with your VPN Server Address):

Replace the file content with the following (replace your_user_name and your_password with your VPN credentials):

Run the following command each time you want to start the ipsec and l2tp connection:

Check the output. You should now see a new interface ppp0. Interface ppp0 is needed to continue to the next step.

Routing traffic to an IP address in your internal network. Replace x.x.x.x with the addres you wish to communicate with through the tunnel device:

Error: Unable to resolve host on EC2 instances

If you did run the route command on an EC2 instance and got the error «unable to resolve host : Resource temporarily unavailable» , do the following and then rerun the commands from the Connect and Router sections.

Copy the hostname, from the error message, which will contain the private IP address in the form ip-x-x-x-x . For instance ip-172-31-26-197

Open the hosts file

Add a new entry within the hosts file to include the hostname:

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Openswan L2TP/IPsec VPN client setup

This article or section needs language, wiki syntax or style improvements. See Help:Style for reference.

This article describes how to configure and use a L2TP/IPsec Virtual Private Network client on Arch Linux. It covers the installation and setup of several needed software packages. L2TP refers to the w:Layer 2 Tunneling Protocol and for w:IPsec, the Openswan implementation is employed.

This guide is primarily targeted for clients connecting to a Windows Server machine, as it uses some settings that are specific to the Microsoft implementation of L2TP/IPsec. However, it is adaptable with any other common L2TP/IPsec setup. The Openswan wiki features instructions to set up a corresponding L2TP/IPSec Linux server.

Contents

Installation

To use with NetworkManager, install the networkmanager-l2tp and strongswan packages.

Now you can start openswan.service . If it’s not running you may get an error message about a missing pluto_ctl connect(pluto_ctl) failed: No such file or directory .

Run ipsec verify to check your configuration and resolve possible issues before continuing.

Configuration

NetworkManager

Open the NetworkManager UI, then:

1. Go to Network > VPN. Click «+»
2. Select «Layer 2 Tunneling Protocol (L2TP).»
3. You can choose a name for the VPN.
4. Enter Your VPN Server IP for the Gateway.
5. Enter Your VPN Username for the User name.
6. Right-click the ? in the Password field, select Store the password only for this user. (If this option gives you trouble, you might want to use «Store password for all users»)
7. Enter Your VPN Password for the Password.
8. Leave the NT Domain field blank.
9. Click the IPsec Settings. button.
10. Check the Enable IPsec tunnel to L2TP host checkbox.
11. Leave the Gateway ID field blank.
12. Enter Your VPN IPsec PSK for the Pre-shared key.
13. OK, then click Add to save the VPN connection information.

Now you should be able to start the VPN, by switching the Toggle-Button on.

OpenSwan

Edit /etc/ipsec.conf to contain the following lines:

This file contains the basic information to establish a secure IPsec tunnel to the VPN server. It enables NAT Traversal for if your machine is behind a NAT’ing router (most people are), and various other options that are necessary to connect correctly to the remote IPsec server. The next file contains your pre-shared key (PSK) for the server.

Create the file /etc/ipsec.secrets : It should contain the following line:

Remember to replace the local ( 192.168.0.123 ) and remote ( 68.68.32.79 ) IP addresses with the correct numbers for your location. The pre-shared key will be supplied by the VPN provider and will need to be placed in this file in cleartext form. You may find this file already exists and already have some data, try to back it up and create a new file only with your PSK if you will see «Can’t authenticate: no preshared key found for . » when enabling connection in next section. Do not forget to set proper permissions (600) for this file or you will get error message «We cannot identify ourselves with either end of this connection.».

Add the connection, so it’s available to use:

At this point the IPsec configuration is complete and we can move on to the L2TP configuration.

Running Openswan in a container

Do not forget to add CAP_SYS_MODULE capability and access to host module tree. Example for nspawn:

xl2tpd

Edit /etc/xl2tpd/xl2tpd.conf so it has the following contents:

This file configures xl2tpd with the connection name, server IP address (which again, please remember to change to your servers address) and various options that will be passed to pppd once the tunnel is set up.

Now create /etc/ppp/options.l2tpd.client with the following contents:

Place your assigned username and password for the VPN server in this file. A lot of these options are for interoperability with Windows Server L2TP servers. If your VPN server uses PAP authentication, replace require-mschap-v2 with require-pap .

This concludes the configuration of the applicable software suites to connect to a L2TP/IPsec server. To start the connection do the following:

At this point the tunnel is up and you should be able to see the interface for it if you type:

You should see a pppX device that represents the tunnel. Right now, nothing is going to get routed through it. You need to add some routing rules to make it work right:

Routing

Routing traffic to a single IP address or subnet through the tunnel

This is as easy as adding a routing rule to your kernel table:

Note xxx.xxx.xxx.xxx is the specific ip address (e.g. 192.168.3.10) or subnet (e.g. 192.168.3.0/24) that you wish to communicate with through the tunnel device (e.g. ppp0).

Note yyy.yyy.yyy.yyy is «peer ip» of your pppX device used to route traffic to tunnel destination xxx.xxx.xxx.xxx.

See example below for command to identify tunnel device name and peer ip and then add route. :

Routing all traffic through the tunnel

This is a lot more complex, but all your traffic will travel through the tunnel. Start by adding a special route for the actual VPN server through your current gateway:

This will ensure that once the default gateway is changed to the ppp interface that your network stack can still find the VPN server by routing around the tunnel. If you miss this step you will lose connectivity to the Internet and the tunnel will collapse. Now add a default route that routes to the PPP remote end:

The remote PPP end can be discovered by following the step in the previous section. Now to ensure that ALL traffic is routing through the tunnel, delete the original default route:

To restore your system to the previous state, you can reboot or reverse all of the above steps.

The route creation can also be automated by placing a script in /etc/ppp/ip-up.d.

Troubleshooting

Issue: journalctl logs VPN connection: failed to connect: ‘Could not restart the ipsec service.

Solution Make sure you have strongswan installed

Issue: I get a message from pppd saying «Failed to authenticate ourselves to peer» and I have verified my password is correct. What could be wrong?

Solution 1: If you see the following in your /var/log/daemon.log:

then you are authenticating against a SonicWALL LNS that does not know how to handle CHAP-style authentication correctly.

The solution to this is to add the following to your options.l2tp.client file:

This will cause the SonicWALL to default to the next authentication mechanism, namely MSCHAP-v2. This should authenticate successfully, and from this point xl2tpd should successfully construct a tunnel between you and the remote L2TP server.

Solution 2: If you see the following in your journal after running journalctl -ru xl2tpd as root:

Try adding domain name in front of username in your options.l2tpd.client file (note the double backslash), i.e:

Tips and tricks

Script start up and shut down

You can create some scripts either in your home directory or elsewhere(remember where you put them) to bring up the tunnel then shut it back down.

First, a utility script to automatically discover PPP distant ends:

Next, the script to bring the tunnel up. This will replace the default route, so all traffic will pass via the tunnel:

Finally, the shutdown script, it simply reverses the process:

A further script

Above script really help me work. And notice the script use fixed ip, and someone like me may change net vpn addr, i would like to put my further script below(not sure how to add attachment, so just raw ):

Script to resolve dns names and connect

This article or section needs language, wiki syntax or style improvements. See Help:Style for reference.

Very useful if you have dynamic IP for the server.

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