ip-l2tp

ip l2tp { tunnel | session } { COMMAND | help }

tunnel add tunnel_id TUNNEL_ID peer_tunnel_id PEER_TUNNEL_ID local LOCAL_IP remote REMOTE_IP [encap {udp|ip}] [version {2|3}] [tx_window TX_WINDOW] [rx_window RX_WINDOW] [ipsec] [debug] [debug-packet]
    Adds a new L2TP tunnel with the specified parameters.

tunnel show [tunnel_id TUNNEL_ID]
    Displays information about L2TP tunnels, optionally filtered by tunnel ID.

tunnel del tunnel_id TUNNEL_ID
    Deletes an L2TP tunnel.

session add tunnel_id TUNNEL_ID session_id SESSION_ID peer_session_id PEER_SESSION_ID [username USERNAME] [password PASSWORD] [ip6 LOCAL_IP] [ip REMOTE_IP] [ip6 REMOTE_IP6] [debug]
    Adds a new L2TP session within a tunnel.

session show [tunnel_id TUNNEL_ID session_id SESSION_ID]
    Displays information about L2TP sessions, optionally filtered by tunnel and session ID.

session del tunnel_id TUNNEL_ID session_id SESSION_ID
    Deletes an L2TP session.

help
    Displays help information about the ip-l2tp command.

The ip-l2tp command is a utility in Linux used for configuring and managing Layer 2 Tunneling Protocol (L2TP) tunnels and sessions. It allows administrators to create, modify, and delete L2TP tunnels, which are used to establish VPN connections between two endpoints. The command provides functionalities for setting various parameters such as tunnel ID, peer IP addresses, authentication details, and other relevant tunnel characteristics. Additionally, ip-l2tp allows creating and managing L2TP sessions within a tunnel, each session represents a single connection across the tunnel. This command is typically used in conjunction with other networking tools like iproute2 to configure the underlying routing and network interfaces that support the L2TP tunnel. Proper configuration of L2TP tunnels is essential for securing and managing network traffic flowing through the VPN connection.

Incorrect configuration of L2TP tunnels can lead to network connectivity issues and security vulnerabilities. Using ipsec is highly recommended for security of tunnel.

The debug option in tunnel and session creation enables verbose logging which is useful for troubleshooting L2TP connection problems. The debug-packet option dumps raw packet data.

The encap option determines whether L2TP packets are encapsulated using UDP (default) or directly using IP. Using IP is less common and might require specific kernel configuration.

The ip-l2tp command has evolved alongside the Linux kernel's networking capabilities. It provides a userspace interface to the kernel's L2TP implementation. L2TP has been a widely used VPN protocol, and the ip-l2tp command has been essential for configuring and managing these connections in Linux environments. Over time, improvements have been made to support newer L2TP versions and encryption options.

ip(8), iproute2(8), xl2tpd(8)