How to set up a Multi-Protocol VPN Server using SoftEther¶

Introduction¶

This article explains how to install and configure a multi-protocol VPN server using the SoftEther package. We enable and configure OpenVPN, L2TP over IPsec and SSTP VPN Servers on Linux.

What is SoftEther¶

SoftEther VPN is one of the world’s most powerful and easy-to-use multi-protocol VPN software, made by the good folks at the University of Tsukuba, Japan. It runs on Windows, Linux, macOS, FreeBSD and Solaris and is freeware and open-source. You can use SoftEther for any personal or commercial use free of charge.

Step 1: Create a Virtual Server¶

First, you need to create a CentOS 7 server. As mentioned in SoftEther’s website, SoftEther will work on almost every Linux distribution with kernel v2.4 or above; however, it’s recommended to choose one of these distributions: CentOS, Fedora, or Red Hat Enterprise Linux.

Personally I have only tried it on CentOS 7 64-bit edition, but it has worked perfectly.

Step 2: Update your Server Software¶

Using the command below, update and upgrade your server software packages to the latest version:

• Debian / Ubuntu:

apt-get update && apt-get upgrade

• CentOS / Fedora:

yum upgrade

Step 3: Download SoftEther¶

You can download the latest SoftEther server package for Linux from their website:

• http://www.softether-download.com/en.aspx

Unfortunately, there is no repository in place for getting the latest version of SoftEther, and so we’ll need to download the latest version to use from their site. Therefore, you have to browse their website using a desktop browser to download the package.

First, browse their website on your own computer and choose the appropriate Component, Platform and CPU, then find the link to the appropriate package. This will download the latest stable version (at the time of writing) for Linux x86_64:

wget http://www.softether-download.com/files/softether/v4.20-9608-rtm-2016.04.17-tree/Linux/SoftEther_VPN_Server/64bit_-_Intel_x64_or_AMD64/softether-vpnserver-v4.20-9608-rtm-2016.04.17-linux-x64-64bit.tar.gz

Step 4: Install and Configure SoftEther¶

Now we have to extract the package we received from the SoftEther download page and compile it. The package used in this tutorial is named softether-vpnserver-v4.20-9608-rtm-2016.04.17-linux-x64-64bit.tar.gz so we will extract it using the command below:

tar xzvf softether-vpnserver-v4.20-9608-rtm-2016.04.17-linux-x64-64bit.tar.gz

After extracting it, a directory named vpnserver will be created in the working folder. In order to compile SoftEther, the following tools and packages must be installed on your server:

make, gccbinutils (gcc), libc (glibc), zlib, openssl, readline, and ncurses

Make sure these are installed. You can install all the packages necessary to build SoftEther using the command below:

• Debian / Ubuntu:

apt-get install build-essential -y

• CentOS / Fedora:

yum groupinstall "Development Tools"

Now that we have all the necessary packages installed, we can compile SoftEther using the following commands.

First cd into vpnserver directory:

cd vpnserver

And now run make to compile SoftEther into an executable file:

make

SoftEther will ask you to read and agree with its License Agreement. Select 1 to read the agreement, again to confirm read, and finally to agree to the License Agreement.

SoftEther is now compiled and made into executable files (vpnserver and vpncmd). If the process fails, check if you have all of the requirement packages installed.

Now that SoftEther is compiled we can move the vpnserver directory to someplace else, here we move it to /usr/local:

cd ..
mv vpnserver /usr/local
cd /usr/local/vpnserver/

And then change the files permission in order to protect them:

chmod 600 *
chmod 700 vpnserver
chmod 700 vpncmd

If you like SoftEther to start as a service on start-up create a file named vpnserver in /etc/init.d directory a follows.

First create and open the file using vi:

vi /etc/init.d/vpnserver

And paste the following into the file:

#!/bin/sh
# chkconfig: 2345 99 01
# description: SoftEther VPN Server
DAEMON=/usr/local/vpnserver/vpnserver
LOCK=/var/lock/subsys/vpnserver
test -x $DAEMON || exit 0
case "$1" in
    start)
        $DAEMON start
        touch $LOCK
        ;;
    stop)
        $DAEMON stop
        rm $LOCK
        ;;
    restart)
        $DAEMON stop
        sleep 3
        $DAEMON start
        ;;
    *)
        echo "Usage: $0 {start|stop|restart}"
        exit 1
esac
exit 0

Finally save and close the file by pressing esc and typing :wq to close vi.

We have to make a directory at /var/lock/subsys if one does not exist:

mkdir /var/lock/subsys

Now change the permission for the start-up script and start vpnserver using command below:

chmod 755 /etc/init.d/vpnserver && /etc/init.d/vpnserver start

Use the command below make it to run at start-up:

update-rc.d vpnserver defaults

chkconfig --add vpnserver

cd /usr/local/vpnserver
./vpncmd

check

Step 5: Generate a Let’s Encrypt certificate¶

Check out this link for a guide on using Certbot to automate generating Let’s Encrypt certificates: SafeDNS Authenticator plugin for Certbot

Further reading: https://certbot.eff.org/docs/using.html

Install the certbot package from the EPEL repository as follows:

yum install epel-release
yum install certbot

Decide what domain name to use to point to our VPN server:

FQDN=vpn.mydomainname.com

Here we’ll use the standalone option to create a temporary web server listening on port 80. We specify the challenge type http-01 as the SoftEther will be listening on port 443/tcp.

certbot certonly --standalone-supported-challenges http-01 --standalone -d vpn.mydomainname.com

If certbot managed to generate and validate your certificate, then you should receive a message like the following:

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at
   /etc/letsencrypt/live/vpn.mydomainname.com/fullchain.pem. Your cert
   will expire on 2017-01-17. To obtain a new or tweaked version of
   this certificate in the future, simply run certbot again. To
   non-interactively renew *all* of your certificates, run "certbot
   renew"
 - If you like Certbot, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le

Certbot will have generated a number of files now including the private key, certificate, full certificate chain, etc. and stored them in /etc/letsencrypt/live/vpn.mydomainname.com

We can now add the automatic renewal command into cron so that the certificate will be auto-renewed before it expires. You’ll need to do this yourself, but the command to renew the certificate is:

certbot renew --quiet

Step 6: Change Admin Password¶

Now that you have SoftEther VPN server installed, you have to assign an administrator password in order to use with SoftEther. You can do this using vpncmd which is SoftEther’s command line based administration tool:

./vpncmd

Press 1 to select Management of VPN Server or VPN Bridge, then press Enter without typing anything to connect to the localhost server, and again press Enter without inputting anything to connect to server by server admin mode.

Then use command below to set the admin password:

ServerPasswordSet

Enter and then re-type your new password. You’ll need this whenever you want to change the server-wide options, like the IPSEC Pre-Shared Key (PSK).

Step 7: Create A Virtual Hub¶

To use SoftEther we must first create a Virtual Hub. Here as an example we create a hub named VPN, in order to do that enter command below in the vpncmd tool:

HubCreate VPN

Next you will be asked to enter an administrator password for the hub. This password will be used whenever you are not logged in as server admin mode, and you want to manage that specific hub.

Now select the Virtual Hub you created using this command:

Hub VPN

Step 8: Enable SecureNAT¶

There are two ways of connecting your hubs to the server network:

• using a Local Bridge connection

• using the SecureNAT function.

You can use each one separately, but using these two together will cause problems.

Here we use SecureNAT, which is very easy to setup and works pretty well in most situations. You could also use Local Bridge mode, but then you have to install and configure a DHCP Server too.

SecureNAT is a combination of Virtual NAT and DHCP Server function. By default, it will allocate the VPN clients from the subnet 192.168.30.0/24, although this can be configured.

You can enable SecureNAT using the command below:

SecureNatEnable

If you require split routing, whereby all VPN client traffic will not be forced over the VPN, set the /GW:none option in the DhcpSet command.

Unfortunately, you need to specify the full DHCP configuration again, so get the current values using DhcpGet first. Here’s an example:

DhcpSet /START:192.168.30.10 /END:192.168.30.10 /MASK:192.168.30.10 /EXPIRE:7200 /GW:none /DNS:192.168.30.1 /DNS2:8.8.8.8 /DOMAIN:none /LOG:yes /PUSHROUTE:none

Step 9: Create and Manage Users¶

Now we have to create users for our Virtual Hub to use the VPN. We can create users for our Virtual Hub using the command UserCreate and view the list of current users by using UserList. Users can be added to groups and can even have different types of authentication modes (including: Password, Certificate, RADIUS, NTLM, etc.).

By using command UserCreate we create a user named test:

UserCreate test

The default type of authentication is Password but we can change it to a different type using commands below:

• UserNTLMSet for NT Domain Authentication

• UserPasswordSet for Password Authentication

• UserAnonymousSet for Anonymous Authentication

• UserRadiusSet for RADIUS Authentication

• UserCertSet for Individual Certificate Authentication

• UserSignedSet for Signed Certificate Authentication

In this tutorial we use Password as the user authentication mode for our test user, so using this command set a password for user test:

UserPasswordSet test

Step 10: Setup L2TP/IPsec¶

To enable L2TP/IPsec VPN server you can use the command below:

IPsecEnable

After entering this command, you will be asked to configure the L2TP server functions:

• Enable L2TP over IPsec Server Function: Choose yes to enable L2TP VPN over IPsec with pre-shared key encryption. Now you can make VPN connections to this server using iPhone, Android, Windows, and Mac OS X devices.

• Enable Raw L2TP Server Function: This will enable L2TP VPN for clients with no IPsec encryption.

• Enable EtherIP / L2TPv3 over IPsec Server Function: Routers which are compatible with EtherIP / L2TPv3 over IPsec can connect to this server by enabling this function.

• Pre Shared Key for IPsec: Enter a pre-shared key to use with L2TP VPN.

• Default Virtual HUB in a case of omitting the HUB on the Username: Users can specify the Virtual Hub they are trying to connect to by using Username@TargetHubName as their username when connecting. This option specifies which Virtual Hub to be used if the user does not provide such information. In our case enter VPN.

Step 11: Setup SSTP/OpenVPN¶

The SoftEther can clone the functions of Microsoft SSTP VPN Server and OpenVPN Server. But before we enable these we have to import the SSL certificate and key from Let’s Encrypt.

Here we use SoftEther’s ServerCertSet command to point it to the SSL certificate and key for our server. Change the vpn.mydomainname.com to the FQDN which you provided to Let’s Encrypt’s Certbot tool, which should be the same one which points to your VPN server. It’s imperative that it matches the one you will use long-term:

ServerCertSet /LOADCERT:/etc/letsencrypt/live/vpn.mydomainname.com/fullchain.pem /LOADKEY:/etc/letsencrypt/live/vpn.mydomainname.com/privkey.pem

Now that we have created and registered a SSL Certificate for our server, we can enable SSTP function with this command:

SstpEnable yes

And to enable OpenVPN:

OpenVpnEnable yes /PORTS:1194

• Note: OpenVPN’s default port is 1194, but you can change it to any port you want by changing the /PORTS:1194 part of the command above to your desired port or ports (yes, it supports multiple ports).

After you enabled OpenVPN, you can download a sample configuration file for OpenVPN client. Here we create a sample OpenVPN configuration file and save it to my_openvpn_config.zip:

OpenVpnMakeConfig ~/my_openvpn_config.zip

Then you can download it using any SFTP client such as FileZilla and apply it to your OpenVPN clients.

SoftEther also provides a dedicated VPN Client software for both Windows and Linux. It supports a SoftEther specific protocol called Ethernet over HTTPS or SSL-VPN which is very powerful. It uses HTTPS protocol and port 443 in order to establish a VPN tunnel, and because this port is well-known, almost all firewalls, proxy servers and NATs can pass the packet. In order to use SSL-VPN protocol, you must download and install SoftEther VPN Client, which can be obtained from their website.

Alternatively, and what we’ll do here, you can use the built-in VPN capabilities of Windows 7 or above.

Step 12: Set up IP Forwarding¶

We have to query the sysctl kernel value net.ipv4.ip_forward to see if forwarding is enabled or not:

sysctl net.ipv4.ip_forward

If it’s not currently enabled, the output should be as follows. If the output is 1 then it is already enabled

net.ipv4.ip_forward = 0

Now edit the file /etc/sysctl.conf and add the following line:

net.ipv4.ip_forward = 1

Apply the configuration with the following command

sysctl -p

Step 1: Open Network and Sharing Centre¶

Start by finding the network connections icon in the bottom right corner of the screen (near the clock). The icon can be in the shape of computer display or wireless signal meter. Right click on that icon.

Select Open Network and Sharing Centre. You can also get there by going through Start button > Control Panel > View network status and tasks.

Step 2: Set up a new connection or network¶

Click Set up a new connection or network.

Step 3: Connect to a workplace¶

In the appeared window select Connect to a workplace, click Next.

Step 4: Set as VPN¶

Click Use my Internet connection (VPN).

Step 5: Specify the VPN Server¶

Internet address is your server’s FQDN which was used in Step 5 of “Set up the VPN server”. It is not openstackvpn.calv.tk, that is just an example. Destination name can be anything you like, for example OpenStack VPN.

Check Don’t connect now; just set it up so I can connect later and click Next.

Step 6: Enter login credentials¶

Fill the User name and Password fields. In the Step 9 of “Set up the VPN server” we created the user test, so enter those details (or the ones you used instead). Check Remember this password and click Create.

Step 7: Create the connection¶

Click Close.

Step 8: Find the new connection¶

Click Change adapter settings.

Step 9: Enter connection properties¶

In the connections list find the OpenStack VPN connection, the description should be WAN Miniport (IKEv2). Right click on it and select Properties.

Step 10: Set advanced options¶

Click Security tab, for Type of VPN select Secure Socket Tunnelling Protocol (SSTP). For Data encryption select Require encryption (disconnect if server declines). Click Advanced settings. For Authentication select Unencrypted password (PAP) and Microsoft CHAP Version 2 (MS-CHAP v2). Then click OK

Step 11: Start the VPN connection¶

Double click on the OpenStack VPN connection icon, or whatever you called yours.

Step 12: Verify / enter login details¶

It will show the connection window. Check Save this user name and password for the following users and leave Me only selected. Click Connect button.

Step 13: Check you’re connected¶

After a few seconds it will connect and show you Connected status. You can also check the VPN status in the Network applet (the icon in your system tray at the bottom right). Click on that icon and you will see the connection list and their statuses.