how to setup l2tp vpn on ubuntu 25.10

What you will read?

1 Step 1: Install Required Packages
2 Step 2: Configure IPsec
3 Step 3: Configure L2TP
4 Step 4: Configure PPP
5 Step 5: Start and Enable Services
6 Step 6: Configure Firewall
7 Step 7: Connect via Network Manager

Setting up an L2TP VPN on Ubuntu 25.10 allows you to create a secure, encrypted connection to a remote network. This guide will walk you through all the necessary steps to get your VPN running properly, including installation, configuration, and connection using Network Manager.

Step 1: Install Required Packages

Install the necessary packages to enable L2TP VPN support on Ubuntu, including Network Manager, IPsec, and xl2tpd.

sudo apt update
sudo apt install network-manager-l2tp-gnome strongswan xl2tpd -y

Step 2: Configure IPsec

IPsec encrypts your VPN traffic, ensuring a secure and private connection between your Ubuntu 25.10 system and the VPN server. Proper configuration is essential for authentication and stable VPN performance.

sudo nano /etc/ipsec.conf

Add the following, replacing VPN_SERVER_IP with your server address:

config setup
  charondebug="ike 1, knl 1, cfg 0"

conn l2tp
  keyexchange=ikev1
  authby=secret
  type=transport
  left=%defaultroute
  leftprotoport=17/1701
  right=VPN_SERVER_IP
  rightprotoport=17/1701
  auto=start

Step 3: Configure L2TP

The L2TP configuration defines the tunnel through which your VPN traffic travels. Setting the correct IP range, local IP, and authentication options ensures a stable and secure connection between your Ubuntu system and the VPN server.

sudo nano /etc/xl2tpd/xl2tpd.conf

Add the following configuration, replacing SERVER_IP with your server address:

[global]
ipsec saref = yes
listen-addr = SERVER_IP

[lns default]
ip range = 192.168.100.10-192.168.100.20
local ip = 192.168.100.1
require chap = yes
refuse pap = yes
require authentication = yes
name = l2tpclient
ppp debug = yes
pppoptfile = /etc/ppp/options.l2tpd
length bit = yes

Step 4: Configure PPP

PPP settings handle authentication for your VPN connection. Providing the correct username, password, and DNS ensures your connection can authenticate and resolve addresses properly.

sudo nano /etc/ppp/options.l2tpd

Add the following configuration:

# PPP Configuration
name VPN_USERNAME
password VPN_PASSWORD
refuse-pap
require-chap
ms-dns 8.8.8.8
mtu 1410
mru 1410
persist
noauth

Step 5: Start and Enable Services

Once configuration files are set, you need to start the services responsible for L2TP and IPsec. Enabling them ensures they run automatically after server restarts.

sudo systemctl restart strongswan xl2tpd
sudo systemctl enable strongswan xl2tpd

Step 6: Configure Firewall

For a secure VPN, specific UDP ports must be open. Configuring the firewall allows VPN traffic to pass without blocking legitimate connections.

sudo ufw allow 500,4500/udp
sudo ufw reload

Step 7: Connect via Network Manager

Use Network Manager to create and activate your L2TP VPN connection easily with a graphical interface.

nm-connection-editor

L2TP VPN Setup:

# 1. Click "Add" → Select "Layer 2 Tunneling Protocol (L2TP)" → Create
# 2. Enter connection name, server IP, username, and password
# 3. Enable "IPsec tunnel" and enter the pre-shared key
# 4. Save and connect