Zeroconf or Zero Configuration Networking is a set of techniques that automatically create a usable IP network without configuration or special servers. This allows unknowledgeable users to connect computers, networked printers, and other items together and expect them to work automatically. Without Zeroconf or something similar, a knowledgeable user must either set up special servers, like DHCP and DNS, or set up each computer's network settings by hand, which is a tedious task, and is challenging for non-technical people. The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. ... The application layer is the 7 th seventh level of the seven-layer OSI model. ... The domain name system (DNS) stores and associates many types of information with domain names, but most importantly, it translates domain names (computer hostnames) to IP addresses. ... Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL), are cryptographic protocols which provide secure communications on the Internet for such things as web browsing, e-mail, Internet faxing, and other data transfers. ... Trivial File Transfer Protocol (TFTP) is a very simple file transfer protocol, with the functionality of a very basic form of FTP; it was first defined in 1980. ... FTP or file transfer protocol is used to connect two computers over the Internet so that the user of one computer can transfer files and perform file commands on the other computer. ... Hypertext Transfer Protocol (HTTP) is a method used to transfer or convey information on the World Wide Web. ... The Internet Message Access Protocol (commonly known as IMAP4, and previously called Internet Mail Access Protocol) is an application layer Internet protocol that allows a local client to access e-mail on a remote server. ... IRC redirects here. ... In computing, local e-mail clients use the Post Office Protocol version 3 (POP3), an application-layer Internet standard protocol, to retrieve e-mail from a remote server over a TCP/IP connection. ... The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. ... Simple Mail Transfer Protocol (SMTP) is the de facto standard for e-mail transmissions across the Internet. ... The simple network management protocol (SNMP) forms part of the internet protocol suite as defined by the Internet Engineering Task Force (IETF). ... To meet Wikipedias quality standards, this article or section may require cleanup. ... TELNET is a network protocol used on the Internet or local area network LAN connections. ... The Real-time Transport Protocol (or RTP) defines a good standardized packet format for delivering audio and video over the Internet. ... The Transmission Control Protocol (TCP) is a virtual circuit protocol that is one of the core protocols of the Internet protocol suite, often simply referred to as TCP/IP. Using TCP, applications on networked hosts can create connections to one another, over which they can exchange streams of data. ... The User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. ... In computer networking, IntServ or integrated services is a system that attempts to guarantee quality of service (QoS) on networks. ... The Datagram Congestion Control Protocol (DCCP) is a message-oriented transport layer protocol that is currently under development in the IETF. Applications that might make use of DCCP include those with timingconstraints on the delivery of data such that reliable in-order delivery, when combined with congestion control, is likely... The Stream Control Transmission Protocol (SCTP) is a transport layer protocol defined in 2000 by the IETF Signaling Transport (SIGTRAN) working group. ... The network layer is level three of the seven level OSI model. ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... Internet Protocol version 4 is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. ... Internet Protocol version 6 (IPv6) is a network layer IP standard used by electronic devices to exchange data across a packet-switched internetwork. ... The Internet Control Message Protocol (ICMP) is one of the core protocols of the Internet protocol suite. ... The Internet Group Management Protocol is a communications protocol used to manage the membership of Internet Protocol multicast groups. ... In computer networking, the Address Resolution Protocol (ARP) is the method for finding a hosts hardware address when only its network layer address is known. ... Reverse address resolution protocol (RARP) is a protocol used to resolve an IP address from a given hardware address (such as an Ethernet address). ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Ethernet is a large and diverse family of frame-based computer networking technologies for local area networks (LANs). ... Wi-Fi® (also WiFi, wifi, etc. ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ... Asynchronous Transfer Mode (ATM) is a cell relay network protocol which encodes data traffic into small fixed-sized (53 byte; 48 bytes of data and 5 bytes of header information) cells instead of variable sized packets (sometimes known as frames) as in packet-switched networks (such as the Internet Protocol... In the context of computer networking, frame relay (also found written as frame-relay) consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... General Packet Radio Service (GPRS) is a mobile data service available to users of GSM mobile phones. ... Bluetooth logo Bluetooth is an industrial specification for wireless personal area networks (PANs). ... The physical layer is level one in the seven level OSI model of computer networking as well as in the five layer TCP/IP reference model. ... A modem (from modulate and demodulate) is a device that modulates an analogue carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. ... ISDN is also short for isosorbide dinitrate Integrated Services Digital Network (ISDN) is a type of circuit switched telephone network system, designed to allow digital (as opposed to analog) transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher speeds, than available with analog... Synchronous optical networking, is a method for communicating digital information using lasers or light-emitting diodes (LEDs) over optical fiber. ... RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ... Note: USB may also mean upper sideband in radio. ... It has been suggested that this article or section be merged with Varieties of Ethernet. ... Wi-Fi® (also WiFi, wifi, etc. ... Not to be confused with Get Some Mates The Global System for Mobile Communications (GSM) is the most popular standard for mobile phones in the world. ... Bluetooth logo Bluetooth is an industrial specification for wireless personal area networks (PANs). ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The domain name system (DNS) stores and associates many types of information with domain names, but most importantly, it translates domain names (computer hostnames) to IP addresses. ...

Zeroconf was pioneered by Apple Computer employee Stuart Cheshire in the company's move from AppleTalk to IP. Apple Computer, Inc. ... Stuart is the author of Bolo, a networked tank game, originally written for the BBC Micro and later ported to the Apple Macintosh. ... AppleTalk is a proprietary suite of protocols developed by Apple Computer for computer networking. ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ...

Problems solved

Zeroconf currently solves three problems :

• Choose numeric network addresses for networked items
• Figure out which computer has a certain name
• Figure out where to get services, like printing (service discovery)

Service discovery protocols are network protocols which allow automatic detection of devices and services offered by these devices on a computer network. ...

Choosing addresses

Both IPv4 and IPv6 have standard ways of choosing IP addresses without help. By RFC 3927, IPv4 uses the 169.254.* (link-local) set of addresses. Internet Protocol version 4 is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. ... Internet Protocol version 6 (IPv6) is a network layer IP standard used by electronic devices to exchange data across a packet-switched internetwork. ...

The technique for IPv4 is called IPv4 Link-Local (IPV4LL) in the RFC, however Microsoft refers to this as Automatic Private IP Addressing (APIPA) or Internet Protocol Automatic Configuration (IPAC).

Name resolution

There are two very similar ways of figuring out which networked item has a certain name. Apple Computer's Multicast DNS (mDNS) is in use, and is published freely, though not by a standardization body. Microsoft's Link-local Multicast Name Resolution (LLMNR) is little used, but is in the process of standardization by the IETF.[1]

The two protocols have minor differences. mDNS allows a network device to choose a domain name in the ".local" namespace and announce it using a special multicast IP address. This introduces special semantics for the .local namespace, which is considered a problem by some members of the IETF.[2][3] The current LLMNR draft allows a network device to choose any domain name, which is considered a security risk by some members of the IETF.[4] mDNS is compatible with DNS-SD as described in the next section, while LLMNR is not. More details on the differences are at [5]

Service discovery

Apple's protocol: mDNS/DNS-SD

DNS Service Discovery (DNS-SD) is Apple's lightweight solution, built on top of the tested and robust Domain Name System. It is used in Apple products, many network printers and a considerable number of third party products and applications on various operating systems. It is considered simpler and easier to implement than Microsoft's competing technology, SSDP, because it uses DNS rather than HTTP. It uses DNS SRV (RFC 2782), TXT, and PTR records to advertise Service Instance Names. The hosts offering the different services publish details of available services like instance, service type, domain name and optional configuration parameters. Service types are given informally on a first-come basis. A service type registry is maintained and published by DNS-SD.org. DNS may refer to: Domain Name System Direct numerical simulation Doctor of Nursing Science 3,5-dinitrosalicylic acid This page concerning a three-letter acronym or abbreviation is a disambiguation page—a list of articles associated with the same title. ... The domain name system (DNS) stores and associates many types of information with domain names, but most importantly, it translates domain names (computer hostnames) to IP addresses. ...

Almost all Mac OS software such as the Safari browser and the iChat instant messaging software use DNS-SD. On Windows, many instant messaging and VoIP clients such as Gizmo support DNS-SD. On Linux, many Linux distributions already include DNS-SD functionality. Mac OS, which stands for Macintosh Operating System, is a series of graphical user interface-based operating systems developed by Apple Computer for their Macintosh line of computer systems. ... Safari is a web browser developed by Apple Computer, Inc. ... iChat is an AOL Instant Messenger (AIM), ICQ and Jabber client for Mac OS X. Using a Jabber-like protocol and Bonjour for user discovery, it also allows for LAN communication. ... IP Telephony, also called Internet telephony, is the technology that makes it possible to have a telephone conversation over the Internet or a dedicated Internet Protocol (IP) network instead of dedicated voice transmission lines. ... Gizmo is a placeholder name for any small technological item. ...

Microsoft's protocol: uPNP SSDP

Simple Service Discovery Protocol (SSDP) is a UPnP protocol, used in Windows XP and several brands of network equipment. Despite its name, it is considered complex and requires more effort to implement than DNS-SD. SSDP uses HTTP notification announcements that give a service-type URI and a Unique Service Name (USN). Service types are regulated by the Universal Plug and Play Steering Committee. Simple Service Discovery Protocol (SSDP) is an expired IETF Internet draft by Microsoft and Hewlett-Packard. ... Universal Plug and Play (UPnP) is a set of computer network protocols promulgated by the UPnP Forum. ... Windows XP is a line of operating systems developed by Microsoft Corporation for use on general-purpose computer systems, including home and business desktops, notebook computers, and media centers. ... Uri is one of the 26 cantons of Switzerland. ...

SSDP is supported in many SOHO firewall appliances, where host computers behind it may pierce holes for applications. It is also used in media center systems, where media exchange between host computers and the media center are facilitated using SSDP. Soho is an area of central Londons West End in the borough the City of Westminster. ... It has been suggested that Media Server be merged into this article or section. ...

Efforts toward an IETF standard protocol

Service Location Protocol (SLP), the only protocol for service discovery to have reached the IETF RFC status, is usually ignored by large vendors, except Hewlett-Packard's network printers, Novell, Sun Microsystems, and Apple Computer. SLP is described in RFC 2608; it is not yet an IETF Standard or Draft Standard, although implementations are available for both Solaris and Linux. The Service Location Protocol (SLP, srvloc) allows computers and other devices to find services in a local area network without prior configuration. ... Novell was also the name of a road bicycle racing team. ... Sun Microsystems, Inc. ... Apple Computer, Inc. ... Look up Solaris in Wiktionary, the free dictionary. ... Linux (also known as GNU/Linux) is a Unix-like computer operating system. ...

Standardization

RFC 3927, a standard for choosing addresses for networked items, was published in March 2005 by the Zeroconf IETF working group, which included individuals from Apple, Sun, and Microsoft. 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ...

The DNSEXT IETF working group is working on standardizing LLMNR for figuring out which networked item has which name. Apple's mDNS won't probably be standardized, because it has largely been developed outside of the DNS extension working group.

RFC 2608, the SLP standard for figuring out where to get services, was published by the SVRLOC IETF working group.

Implementations

Apple Bonjour

The most widely adopted Zeroconf solution is Bonjour (formerly Rendezvous) from Apple Computer, which uses multicast DNS and DNS Service Discovery. Apple changed its preferred Zeroconf technology from SLP to mDNS and DNS-SD between Mac OS 10.1 and 10.2, though SLP continues to be supported by Mac OS. Bonjour, formerly Rendezvous, is Apples trade name for its implementation of the IETF Zeroconf specification framework, a computer network technology used in Apples Mac OS X from version 10. ... Apple Computer, Inc. ...

Apple's mDNSResponder has interfaces for C and Java and is available on BSD, Mac OS X, Linux, other POSIX based operating systems and Windows.[6][7] Wikibooks has a book on the topic of C Programming The C programming language (often, just C) is a general-purpose, procedural, imperative computer programming language developed in the early 1970s by Dennis Ritchie for use on the Unix operating system. ... Java is an object-oriented programming language developed by James Gosling and colleagues at Sun Microsystems in the early 1990s. ...

Howl

Howl was a comparatively popular zeroconf implementation from Porchdog software. Many programs implemented support for it. For instance, a Howl-based zeroconf plugin is available for Internet Explorer. Windows Internet Explorer, previously Internet Explorer, abbreviated IE, or MSIE[1], is a graphical web browser developed by Microsoft and included as part of the Microsoft Windows line of operating systems. ...

Avahi

Avahi is a Zeroconf implementation for Linux and BSDs. It implements IPv4LL, mDNS and DNS-SD. It is part of every major and many minor Linux distributions, and is installed by default on e.g. Ubuntu version 6.10. If run in conjunction with nss-mdns it also offers host name resolution. Avahi is a system for multicast DNS service discovery. ... Linux (also known as GNU/Linux) is a Unix-like computer operating system. ... Berkeley Software Distribution (BSD, sometimes called Berkeley Unix) is the Unix derivative distributed by the University of California, Berkeley, starting in the 1970s. ... Ubuntu (IPA pronunciation: ) is a widely used Linux distribution offering an operating system predominantly targeted at personal computers. ...

Avahi also implements binary compatibility libraries that emulate Bonjour and Howl, so software made to use those implementations can also utilize Avahi through the emulation interfaces.

Windows CE 5.0

Windows CE 5.0 includes Microsoft's own implementation of LLMNR.

Link-Local IPv4 Addresses

There are some implementations available:

• Windows and Mac OS have both supported link-local addresses since 1998. Apple released its open-source implementation in the Darwin bootp package.
• Avahi contains a high-quality implementation of IPv4LL in the avahi-autoipd tool.
• zcip (Zero-Conf IP)
• BusyBox embeds a zeroconf implementation (current versions)
• zeroconf, a package based on Simple IPv4LL, a shorter implementation by Arthur van Hoff.

The above implementations are all stand-alone daemons that only deal with link-local IP addresses. Another approach is to modify existing DHCP clients. Hexley, the mascot of Darwin Darwin is a free, open source, Unix-like operating system first released by Apple Computer in 2000. ... In computing, BusyBox is a program combining many standard Unix utilities into a single small executable. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

• Elvis Pfützenreuter has written a patch for the uDHCP client/server

Neither of these implementations addresses kernel issues like the broadcasting of ARP replies or closing of existing network connections.

See also

• Wireless Zero Configuration

what is this. This article or section is not written in the formal tone expected of an encyclopedia article. ...

Implementation links

• Avahi, a free-software (LGPL) implementation of mDNS/DNS-SD and IPv4LL for Linux, NetBSD, FreeBSD and Darwin/MacOSX
• Bonjour, an implementation of DNS-SD by Apple Computer
• JmDNS in Java
• Liaison
• mdnsd, embeddable Multicast DNS Daemon without DNS-SD
• pyZeroConf, Python service discovery
• tmdns, tiny multicast DNS, from the same project as ZCIP
• Multicast DNS

Avahi is a system for multicast DNS service discovery. ... Bonjour, formerly Rendezvous, is Apples trade name for its implementation of the IETF Zeroconf specification framework, a computer network technology used in Apples Mac OS X from version 10. ... Python is an interpreted programming language created by Guido van Rossum in 1990. ...

References

• Erik Guttman (2001). "Autoconfiguration for IP Networking: Enabling Local Communication". IEEE Internet Computing 5 (3): 81-86.
• Zeroconf.org - Stuart Cheshire's page, including expired internet drafts.
• "Understanding Zeroconf and Multicast DNS", December 2002 article, very slightly outdated, on the O'Reilly Network.
• AIR Wiki : ZeroconfTechnologies
• Charter of the DNSEXT working group, which coordinates LLMNR standarization
• Explanation of .local addresses, which are used with mDNS but not yet standardized by IANA
• DNS-SD.org DNS Service Discovery
• UPnP consortium
• RFC 2608, Service Location Protocol, Version 2

For other uses of IANA, see IANA (disambiguation). ...

Books

• Zero Configuration Networking: The Definitive Guide, by Daniel Steinberg and Stuart Cheshire, O'Reilly

Videos

• Zeroconf tech talk by Stuart Cheshire to Google engineers.