Point-to-Point Protocol daemon (PPPD) is the

daemon A demon is a malevolent supernatural being, evil spirit or fiend in religion, occultism, literature, fiction, mythology and folklore. Demon, daemon or dæmon may also refer to: Entertainment Fictional entities * Daemon (G.I. Joe), a character ...

that implements

Point-to-Point Protocol In computer networking, Point-to-Point Protocol (PPP) is a data link layer (layer 2) communication protocol between two routers directly without any host or any other networking in between. It can provide loop detection, authentication, transmissio ...

(PPP). PPP is used to manage network connections between two nodes on

Unix-like operating system A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Uni ...

s. It is configured using

command-line argument A command-line interface (CLI) is a means of interacting with software via command (computing), commands each formatted as a line of text. Command-line interfaces emerged in the mid-1960s, on computer terminals, as an interactive and more user ...

s and

configuration file A configuration file, a.k.a. config file, is a computer file, file that stores computer data, data used to configure a software system such as an application software, application, a server (computing), server or an operating system. Some applic ...

s. While it has initially been used to manage only

dial-up access Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telepho ...

, it is also used to manage

broadband In telecommunications, broadband or high speed is the wide-bandwidth (signal processing), bandwidth data transmission that exploits signals at a wide spread of frequencies or several different simultaneous frequencies, and is used in fast Inter ...

connections such as

DSL Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric di ...

, if

Point-to-Point Protocol over Ethernet The Point-to-Point Protocol over Ethernet (PPPoE) is a network protocol for encapsulating Point-to-Point Protocol (PPP) frames inside Ethernet frames. It appeared in 1999, in the context of the boom of DSL as the solution for tunneling packe ...

(PPPoE) or

Point-to-Point Protocol over ATM In computer networking, the Point-to-Point Protocol over ATM (PPPoA) is a layer 2 data-link protocol typically used to connect domestic broadband modems to ISPs via phone lines. It is used mainly with DOCSIS and DSL carriers, by encapsulating PPP ...

(PPPoA) is used. The role of pppd is managing PPP session establishment and session termination. During session establishment, pppd has the role of: * Looped link detection: PPP detects looped links using magic numbers. When PPPD sends PPP LCP messages, these messages include a magic number. If a line is looped, the node receives an LCP message with its own magic number, instead of getting a message with the peer's magic number. *Automatic self configuration: Using

Link Control Protocol In computer networking, the Link Control Protocol (LCP) forms part of the Point-to-Point Protocol (PPP), within the family of Internet protocols. In setting up PPP communications, both the sending and receiving devices send out LCP packets to dete ...

it has to negotiate protocol features like Address-and-Control-Field-Compression (ACFC), escaped characters, and the compression, encryption (like MPPE) and authentication methods to use. *Access control and authentication: Using protocols like

Challenge-handshake authentication protocol In computing, the Challenge-Handshake Authentication Protocol (CHAP) is an authentication protocol originally used by Point-to-Point Protocol (PPP) to validate users. CHAP is also carried in other authentication protocols such as RADIUS and Diamete ...

(CHAP) or

Password authentication protocol Password Authentication Protocol (PAP) is a password-based authentication protocol used by Point-to-Point Protocol (PPP) to validate users. PAP is specified in . Almost all network operating systems support PPP with PAP, as do most network access s ...

(PAP) it has to provide and check authentication data. *Layer 3 configuration: If using Internet Protocol Control Protocol (IPCP), it will negotiate or determine IP parameters such as the

IP address An Internet Protocol address (IP address) is a numerical label such as that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface i ...

es, the

maximum transmission unit In computer networking, the maximum transmission unit (MTU) is the size of the largest protocol data unit (PDU) that can be communicated in a single network layer transaction. The MTU relates to, but is not identical to the maximum frame size tha ...

, and

name server A name server is a computer application that implements a network service for providing responses to queries against a directory service. It translates an often humanly meaningful, text-based identifier to a system-internal, often numeric identi ...

addresses. Some versions may also support Internetwork Packet Exchange Control Protocol (IPXCP) and AppleTalk Control Protocol (ATCP) for routing

IPX Internetwork Packet Exchange (IPX) is the network-layer protocol in the IPX/SPX protocol suite. IPX is derived from Xerox Network Systems' IDP. It also has the ability to act as a transport layer protocol. The IPX/SPX protocol suite was very ...

AppleTalk AppleTalk is a discontinued proprietary suite of networking protocols developed by Apple Computer for their Macintosh computers. AppleTalk includes a number of features that allow local area networks to be connected with no prior setup or the ...

over the link. *After negotiation is complete, it has to set up the required network interfaces and routes, so that the connection is run by the

kernel Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learnin ...

. pppd terminates a PPP link when: * too many frames with invalid

frame check sequence A frame check sequence (FCS) is an error-detecting code added to a frame in a communication protocol. Frames are used to send payload data from a source to a destination. Purpose All frames and the bits, bytes, and fields contained with ...

(FCS) field have been received * the link is considered "idle" (if configured) * another program or the peer requests link termination. Some newer versions of pppd are also capable of handling

Dial-on-demand routing Dial on Demand Routing (DDR) is a routing technique where a network connection to a remote site is established only when needed. In other words, if the router tries to send out data and the connection is off, then the router will automatically esta ...

, where pppd sets up a virtual network, captures the packages it receives and establishes a PPP connection and forwards the captured and not-yet transmitted packages over the link.

Frontends and configurators

* kppp – A kde

GUI Gui or GUI may refer to: People Surname * Gui (surname), an ancient Chinese surname, ''xing'' * Bernard Gui (1261 or 1262–1331), inquisitor of the Dominican Order * Luigi Gui (1914–2010), Italian politician * Gui Minhai (born 1964), Ch ...

frontend for pppd. * gnome-ppp – A (discontinued) gnome

frontend for WvDial, which in turns depends on pppd. * pppconfig – It uses the standard ppp configuration files and sets ppp up so that the standard pon and poff commands (to connect and disconnect) and plog (to list the log) can be used to control ppp. It includes modem detection. * WvDial – A

CLI CLI may refer to: Computing * Call Level Interface, an SQL database management API * Command-line interface, of a computer program * Command-line interpreter or command language interpreter; see List of command-line interpreters * CLI (x86 instruc ...

tool which is used for modem initialisation before starting pppd.

References

Manual page A man page (short for manual page) is a form of software documentation found on Unix and Unix-like operating systems. Topics covered include programs, system libraries, system calls, and sometimes local system details. The local host administra ...

: pppd(8) (''man pppd'' in a

Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

terminal Terminal may refer to: Computing Hardware * Computer terminal, a set of primary input and output devices for a computer * Terminal (electronics), a device for joining electrical circuits together ** Battery terminal, electrical contact used to ...

o
pppd man page at ppp.samba.org
.

External links

RP-PPPoE
a PPPoE client, server and relay implementation for Linux.
ACCEL-PPP
high performance PPTP/L2TP/PPPoE/IPoE server for Linux. * {{Freshmeat, pppd, pppd
Apple ppp source
Free network-related software Unix network-related software

Frontends and configurators

References

Further reading

External links