Advanced Setup Guides
L2TP/IPsec and IKEv2 VPN

32min
Setting Up L2TP/IPsec and IKEv2 VPN Server on Ubuntu 22.04
Introduction
This guide provides detailed instructions for setting up a VPN server on Ubuntu 22.04 that supports both L2TP/IPsec and IKEv2 protocols. Using the hwdsl2/setup-ipsec-vpn scripts, you can quickly deploy a secure VPN server. This setup allows clients to connect securely using either L2TP/IPsec or IKEv2, providing flexibility and strong encryption for your VPN connections.
Prerequisites
VPS Server:
An EDIS Global VPS running Ubuntu 22.04.
Root or sudo access.
Client Machine:
A computer running Ubuntu or any Linux distribution compatible with L2TP/IPsec and IKEv2.
Root or sudo access.
Overview
We will perform the following high-level steps:
On the VPS Server:
Update system packages.
Install necessary dependencies.
Run the VPN setup script to configure L2TP/IPsec and IKEv2 VPN server.
Manage VPN users (add or remove).
On the Client Machine:
Install VPN client software.
Configure and establish a VPN connection using L2TP/IPsec or IKEv2.
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Steps on the VPS Server
1. Update and Upgrade System Packages
Ensure your server is up to date.
Text
sudo apt update && sudo apt upgrade -y
sudo apt update && sudo apt upgrade -y
﻿
Explanation: Updates the package lists and upgrades installed packages to their latest versions, ensuring your system is secure and up to date.
2. Install Required Packages
Install curl and wget, which are necessary for downloading scripts and files.
Text
sudo apt install curl wget -y
sudo apt install curl wget -y
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3. Download and Run the VPN Setup Script
Use the setup script from hwdsl2/setup-ipsec-vpn to configure the VPN server.
Text
wget https://get.vpnsetup.net -O vpn.sh
wget https://get.vpnsetup.net -O vpn.sh
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Run the VPN setup script with custom DNS servers (optional).
Text
sudo VPN_DNS_SRV1=1.1.1.1 VPN_DNS_SRV2=1.0.0.1 sh vpn.sh
sudo VPN_DNS_SRV1=1.1.1.1 VPN_DNS_SRV2=1.0.0.1 sh vpn.sh
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Explanation:
VPN_DNS_SRV1 and VPN_DNS_SRV2 set the DNS servers for VPN clients.
The script will prompt you to enter VPN credentials (IPsec PSK, username, password). If not, it will generate them automatically.
Script Output Example:
Text
===============================================

IPsec VPN server is now ready for use!

Connect to your new VPN with these details:

Server IP: x.x.x.x
IPsec PSK: Your_IPsec_PSK
Username: vpnuser
Password: Your_VPN_Password

Write these down. You'll need them to connect!

VPN client setup: https://vpnsetup.net/clients

===============================================

===============================================

IKEv2 setup successful. Details for IKEv2 mode:

VPN server address: x.x.x.x
VPN client name: vpnclient

Client configuration is available at:
/root/vpnclient.p12 (for Windows & Linux)
/root/vpnclient.sswan (for Android)
/root/vpnclient.mobileconfig (for iOS & macOS)

Next steps: Configure IKEv2 clients. See:
https://vpnsetup.net/clients

===============================================
===============================================

IPsec VPN server is now ready for use!

Connect to your new VPN with these details:

Server IP: x.x.x.x
IPsec PSK: Your_IPsec_PSK
Username: vpnuser
Password: Your_VPN_Password

Write these down. You'll need them to connect!

VPN client setup: https://vpnsetup.net/clients

===============================================

===============================================

IKEv2 setup successful. Details for IKEv2 mode:

VPN server address: x.x.x.x
VPN client name: vpnclient

Client configuration is available at:
/root/vpnclient.p12 (for Windows & Linux)
/root/vpnclient.sswan (for Android)
/root/vpnclient.mobileconfig (for iOS & macOS)

Next steps: Configure IKEv2 clients. See:
https://vpnsetup.net/clients

===============================================
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Note: Replace x.x.x.x with your server's public IP address. The script outputs important VPN credentials—keep them secure.
4. Managing VPN Users
Adding a New VPN User
Download the user management script and add a new user.
Text
sudo wget https://get.vpnsetup.net/adduser -O /opt/src/addvpnuser.sh
sudo chmod +x /opt/src/addvpnuser.sh
sudo ln -s /opt/src/addvpnuser.sh /usr/bin/addvpnuser.sh

sudo addvpnuser.sh 'newusername' 'newpassword'
sudo wget https://get.vpnsetup.net/adduser -O /opt/src/addvpnuser.sh
sudo chmod +x /opt/src/addvpnuser.sh
sudo ln -s /opt/src/addvpnuser.sh /usr/bin/addvpnuser.sh

sudo addvpnuser.sh 'newusername' 'newpassword'
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Explanation:
The script addvpnuser.sh allows you to add new VPN users with specified usernames and passwords.
Replace 'newusername' and 'newpassword' with the desired credentials.
Removing a VPN User
Download the user removal script and remove an existing user.
Text
sudo wget https://get.vpnsetup.net/deluser -O /opt/src/delvpnuser.sh
sudo chmod +x /opt/src/delvpnuser.sh
sudo ln -s /opt/src/delvpnuser.sh /usr/bin/delvpnuser.sh

sudo delvpnuser.sh 'username_to_remove'
sudo wget https://get.vpnsetup.net/deluser -O /opt/src/delvpnuser.sh
sudo chmod +x /opt/src/delvpnuser.sh
sudo ln -s /opt/src/delvpnuser.sh /usr/bin/delvpnuser.sh

sudo delvpnuser.sh 'username_to_remove'
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Explanation:
The script delvpnuser.sh allows you to remove VPN users by specifying their username.
Replace 'username_to_remove' with the username you wish to delete.
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Steps on the Client Machine
Option 1: Connect Using L2TP/IPsec
1. Install L2TP VPN Client
Install the Network Manager L2TP plugin.
Text
sudo apt install network-manager-l2tp-gnome -y
sudo apt install network-manager-l2tp-gnome -y
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Explanation: Installs the necessary packages to enable L2TP/IPsec VPN connections via the GNOME Network Manager.
2. Configure the VPN Connection
Follow these steps to set up the VPN connection:
Access VPN Settings:
Go to Settings > Network > VPN.
Click the + button to add a new VPN connection.
Select VPN Type:
Choose Layer 2 Tunneling Protocol (L2TP).
General Configuration:
Name: Enter a name for your VPN connection (e.g., My L2TP VPN).
Gateway: Enter your VPN server's IP address (Your VPN Server IP).
User name: Enter your VPN username (Your VPN Username).
Password: Click the icon next to the password field and select Store the password only for this user. Then enter your VPN password (Your VPN Password).
NT Domain: Leave this field blank.
Configure IPsec Settings:
Click on IPsec Settings....
Enable IPsec tunnel to L2TP host: Check this box.
Pre-shared key: Enter your IPsec PSK (Your VPN IPsec PSK).
Advanced Settings:
Expand the Advanced section.
Phase1 Algorithms: Enter aes128-sha1-modp2048.
Phase2 Algorithms: Enter aes128-sha1.
Save and Connect:
Click OK to close the IPsec settings.
Click Add to save the VPN connection.
In the VPN settings, toggle the VPN switch to ON to connect.
Explanation:
Phase1 and Phase2 Algorithms: These settings ensure compatibility with the VPN server configuration.
3. Verify the VPN Connection
After connecting, verify your IP address to confirm that the VPN is working.
Text
curl ifconfig.me
curl ifconfig.me
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Explanation: This command displays your public IP address, which should now be the VPN server's IP if the connection is successful.
Option 2: Connect Using IKEv2
1. Install StrongSwan Network Manager Plugin
Text
sudo apt install network-manager-strongswan -y
sudo apt install network-manager-strongswan -y
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Explanation: Installs the StrongSwan plugin, enabling IKEv2 VPN connections via the Network Manager.
2. Obtain VPN Client Configuration Files
You need the following files from your VPN server:
vpnclient.p12: Contains the client certificate and private key.
vpnclient.mobileconfig: Configuration profile for macOS/iOS (not needed for Linux).
vpnclient.sswan: StrongSwan configuration file (optional).
Securely copy these files to your client machine:
Text
scp root@Your_VPN_Server_IP:/root/vpnclient.p12 ~/
scp root@Your_VPN_Server_IP:/root/vpnclient.p12 ~/
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Explanation: Replace Your_VPN_Server_IP with your VPN server's IP address.
3. Extract Certificates and Private Key
Create a directory to store the certificates and extract them from the .p12 file.
Text
mkdir ~/ikev2-vpn
cd ~/ikev2-vpn

openssl pkcs12 -in ~/vpnclient.p12 -cacerts -nokeys -out ca.cer
openssl pkcs12 -in ~/vpnclient.p12 -clcerts -nokeys -out client.cer
openssl pkcs12 -in ~/vpnclient.p12 -nocerts -nodes -out client.key

rm ~/vpnclient.p12
mkdir ~/ikev2-vpn
cd ~/ikev2-vpn

openssl pkcs12 -in ~/vpnclient.p12 -cacerts -nokeys -out ca.cer
openssl pkcs12 -in ~/vpnclient.p12 -clcerts -nokeys -out client.cer
openssl pkcs12 -in ~/vpnclient.p12 -nocerts -nodes -out client.key

rm ~/vpnclient.p12
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Explanation:
ca.cer: The CA certificate.
client.cer: Your client certificate.
client.key: Your private key.
Note: If prompted for a password during extraction, simply press Enter.
4. Secure the Certificate and Key Files
It's important to protect these sensitive files.
Text
sudo chown root:root ca.cer client.cer client.key
sudo chmod 600 ca.cer client.cer client.key
sudo chown root:root ca.cer client.cer client.key
sudo chmod 600 ca.cer client.cer client.key
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Explanation: Changes ownership to root and restricts permissions to prevent unauthorized access.
5. Install Network Manager Plugins (If Not Already Installed)
Depending on your Linux distribution, install the necessary packages:
Text
# Ubuntu and Debian
sudo apt update
sudo apt install network-manager-strongswan -y

# Arch Linux
sudo pacman -Syu  # Update package lists
sudo pacman -S networkmanager-strongswan

# Fedora
sudo dnf install NetworkManager-strongswan-gnome

# CentOS
sudo yum install epel-release
sudo yum --enablerepo=epel install NetworkManager-strongswan-gnome
# Ubuntu and Debian
sudo apt update
sudo apt install network-manager-strongswan -y

# Arch Linux
sudo pacman -Syu  # Update package lists
sudo pacman -S networkmanager-strongswan

# Fedora
sudo dnf install NetworkManager-strongswan-gnome

# CentOS
sudo yum install epel-release
sudo yum --enablerepo=epel install NetworkManager-strongswan-gnome
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6. Configure the VPN Connection
Follow these steps to set up the IKEv2 VPN connection:
Access VPN Settings:
Go to Settings > Network > VPN.
Click the + button to add a new VPN connection.
Select VPN Type:
Choose IPsec/IKEv2 (strongSwan).
General Configuration:
Name: Enter a name for your VPN connection (e.g., My IKEv2 VPN).
Gateway Configuration:
Address: Enter your VPN server's IP address or domain name (Your VPN Server IP).
Certificate: Select the ca.cer file you extracted earlier.
Client Authentication:
Authentication: Choose Certificate (/private key).
Certificate (file): Select the client.cer file.
Private key: Select the client.key file.
Options Configuration:
Request an inner IP address: Check this box.
Cipher Proposals (Algorithms):
Enable custom proposals: Check this box.
IKE: Leave this field blank.
ESP: Enter aes128gcm16.
Save and Connect:
Click Add to save the VPN connection.
In the VPN settings, toggle the VPN switch to ON to connect.
Explanation:
Certificates and Keys: The client certificate and private key authenticate your device to the VPN server.
Cipher Proposals: Setting custom proposals ensures that the encryption algorithms match those expected by the VPN server.
7. Verify the VPN Connection
Check your public IP address to confirm that you are connected through the VPN.
Text
curl ifconfig.me
curl ifconfig.me
﻿
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Troubleshooting
Failed to Establish VPN Connection:
Ensure that your server's firewall allows necessary VPN ports (e.g., UDP ports 500 and 4500 for IPsec).
Verify that VPN services are running on the server.
Authentication Errors:
Double-check the VPN credentials (IPsec PSK, username, password).
Ensure that the certificates and keys are correctly installed and permissions are properly set.
DNS Issues:
If you cannot resolve domain names after connecting, specify DNS servers in your VPN client settings or update the VPN server configuration to push DNS settings to clients.
StrongSwan Configuration Errors:
Check logs for errors: /var/log/syslog or use journalctl -xe.
Ensure that the IKEv2 configuration matches between the client and server.
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Conclusion
By following this guide, you've successfully set up a VPN server on Ubuntu 22.04 that supports both L2TP/IPsec and IKEv2 protocols. This configuration enhances your network security by encrypting your internet traffic and providing flexible connection options for various clients.
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References
﻿hwdsl2/setup-ipsec-vpn GitHub Repository﻿
﻿Managing VPN Users﻿
﻿Linux VPN Clients﻿
﻿IKEv2 VPN Setup﻿
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Note: Always ensure your use of VPNs complies with local laws and regulations. Keep your VPN credentials and certificates secure to prevent unauthorized access.
Updated 13 Sep 2024
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