1.1. Overview

Mpd is a netgraph(4) based implementation of the multi-link PPP protocol for FreeBSD. It is designed to be both fast and flexible. It handles configuration and negotiation in user land, while routing all data packets strictly in the kernel. It supports several of the numerous PPP sub-protocols and extensions, such as:

• Multi-link PPP capability
• PAP, CHAP, MS-CHAP and EAP authentication
• PPP compression and encryption
• IPCP and IPV6CP parameter negotiation

Mpd have support for many link types:

• Serial port modem The modem device type supports asychronous serial connections, including modems, ISDN terminal adapters, and null-modem connections. Mpd includes a fully event-driven scripting language for modem identification, setup, manual server login, etc.
• Point-to-Point Tunnelling Protocol (PPTP) Mpd can connect over the Internet using the Point-to-Point Tunnelling Protocol (PPTP). This protocol is supported by the popular Microsoft Dial-Up Networking client.
• Layer Two Tunnelling Protocol (L2TP) Mpd can connect over the Internet using the Layer Two Tunnelling Protocol (L2TP). This protocol is supported by the popular Microsoft Dial-Up Networking client.
• PPP over Ethernet (PPPoE) Mpd can connect over an Ethernet port using the PPP-over-Ethernet (PPPoE) protocol.
• PPP over TCP Mpd can tunnel PPP frames over a TCP connection. Frames are encoded in the same was as asychronous serial connections.
• PPP over UDP Mpd can tunnel PPP frames over a UDP connection. Each frame is encapsulated in a UDP datagram packet.
• PPP over specified netgraph(4) node Netgraph is highly modular kernel networking system, supporting synchronous serial connections, Cisco HDLC, Frame Relay, and other protocols. Mpd supports running PPP over any netgraph connection.

Mpd also includes many additional features:

• IPv4 and IPv6 support
• RADIUS authentication and accounting
• NetFlow traffic accounting
• Network address translation (NAT)
• Dial-on-demand with idle timeout
• Multiple active connections running simultaneously
• Dynamic demand based link management (also known as ``rubber bandwidth'')
• Powerful chat scripting language for asynchronous serial ports
• Pre-tested chat scripts for several common modems and ISDN TAs
• Clean device-type independent design
• Comprehensive logging
• Telnet and HTTP control interfaces.

Mpd was originally developed at Whistle Communications, Inc. for use in the Whistle InterJet. It is based on the original iij-ppp user-mode PPP code, though it has pretty much been completely rewritten since then. Mpd is now hosted on sourceforge.net MPD Project Page.