Wiki: Zero Conf

See: SubEthaEdit

ZeroConf is an IETF working group for allowing ad-hoc TCP/IP networking. The working group goal is to produce RFCs on standards-tracks. Apple released its Rendezvous code in September 2002. More research is required, but it seems that multiple ZeroConf clients can run on a single client machine if necessary. If true, this removes the need to rely on system services, though not completely eliminating the need for slight configuration changes.

• http://www.zeroconf.org/
• Howl - cross-platform implementation of the Zeroconf networking standard
• JmDNS (was Jrendezvous) is a tool allowing other services to use TCP ports based on the Rendezvous code.

At the Apple World Wide Developer Conference in June 2004 announcements were was made regarding their release of Rendezvous to other platforms. A Windows Technology preview is downloadable, a Java interface and code was released for Linux, Solaris & FreeBSD under the APSL. The release page also has a PocketPC version in binary form. A Rendezvous mail list with archives exists as well.

An article giving more context and details about implementations and competing standards.

• http://www.linux-mag.com/2003-08/zeroconf_01.html

It is similar in scope to two previous efforts

• Sun Microsystems Jini
• Microsoft UPnP, based on Simple Service Discovery Protocol (SSDP) and HTTPMU, a multicast variant of HTTP. (UPnp Forum, Linux SDK)

There are actually a set of requirements to provide this capability with differing states of implementation and agreement. I found out about some of these implementations by polling some nice folks in the #twisted IRC channel on freenode.net. Please update this list if you find useful references.

1. assign own IP address (Macs and Windows use 169.254/16 range already)

   • ZCIP (IPv4 link-local auto-configuration): http://zeroconf.sourceforge.net
   • IPv6 already natively supports this functionality
   • gmds - GNOME implementation, CVS only, 2004 May 06 entry on http://planet.gnome.org/ by Bastien Nocera is a good summary
   • a freedesktop project - Tim Jansen gave a talk (kpresenter download) at a KDE conference during Aug 22-30, 2003 held in the Czech Republic.
2. resolve own hostname (i.e. zeus.local)

3. advertise own services

   • DNS-SD - Apple has deployed this as part of Rendezvous, uses DNS as a service discovery protocol (service types, historical RFC2782)
   • LLMNR - based on SLP (see openslp.org, an IETF standards- track protocol)
4. "Originally, there was a fourth requirement that allowed for the allocation of multicast addresses without a MADCAP server, but it was dropped due to a lack of interest." (from article referenced above)