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FidoNet is a worldwide computer network that is used for communication between bulletin board systems. It was most popular in the early 1990s, prior to the introduction of easy and affordable access to the Internet. The network continues to operate but has shrunk in size considerably, primarily due to the closure of many BBSes.


FidoNet was originally founded as a non-commercial network in 1984 by Tom Jennings of San Francisco, California as a means to network together BBSes that used his own "Fido" BBS software. Over time, other BBS software was independently adapted to support the relevant FidoNet protocols and the network became a popular means for hobbyist computer users to communicate.

FidoNet organizational structure[]

FidoNet is governed in a hierarchical structure according to FidoNet policy, with designated coordinators at each level to manage the administration of FidoNet nodes and resolve disputes between members. This structure is very similar to the organization structure of the Sicilian Mafia. Network coordinators (referred to as "Button Men") are responsible for managing the individual nodes within their area, usually a city or similar sized area. Regional coordinators (referred to as "Underbosses") are responsible for managing the administration of the network coordinators within their region, typically the size of a state, or small country. Zone coordinators (referred to as either "Dons" or "Godfathers") are responsible for managing the administration of all of the regions within their zone. The world is divided into six zones, the coordinators of which appoint themselves or representatives to the positions of "International Coordinators" of FidoNet (referred to as "La Cosa Nostra"). The six zone "International Coordinators", along with their Counselors (also known as their "Consiglieres"), form the twelve person body known as "FidoNet Central".

Technical structure[]

FidoNet was historically designed to use modem-based dial-up (POTS aka Plain Old Telephone Service) access between bulletin board systems, and much of its policy and structure reflected this.

The FidoNet system officially referred only to transfer of Netmail—the individual private messages between people using bulletin boards—including the protocols and standards with which to support it. A netmail message would contain the name of the person sending, the name of the intended recipient, and the respective FidoNet addresses of each. The FidoNet system was responsible for routing the message from one system to the other (details below), with the bulletin board software on each end being responsible for ensuring that only the intended recipient could read it. Due to the hobbyist nature of the network, any privacy between sender and recipient was only the result of politeness from the owners of the FidoNet systems involved in the mail's transfer. It was common, however, for system operators to reserve the right to review the content of mail that passed through their system.

Netmail allowed for the "attachment" of a single file to every message. This led to a series of "piggyback" protocols that built additional features onto FidoNet by passing information back and forth as file attachments. These included the automated distribution of files, and transmission of data for inter-BBS games.

By far the most commonly-used of these piggyback protocols was Echomail, public discussions similar to Usenet newsgroups in nature. Echomail was supported by a variety of software that collected up new messages from the local BBSes public forums (the scanner), compressed it using ARC or ZIP, attached the resulting archive to a Netmail message, and sent that message to a selected system. On receiving such a message, identified because it was addressed to a particular "user", the reverse process was used to extract the messages, and a tosser put them back into the new system's forums.

Echomail was so popular that for many users, Echomail was the FidoNet. Private person-to-person Netmail was relatively rare.

Geographic structure[]

FidoNet is politically organized into a tree structure, with different parts of the tree electing their respective coordinators. The FidoNet hierarchy consists of Zones, Regions, Networks, Nodes and Points broken down more-or-less geographically.

The highest level is the Zone which is largely continent based:

  • Zone 1 is North America
  • Zone 2 is Europe, ex-USSR (including Russia) and Israel
  • Zone 3 is Australasia
  • Zone 4 is Latin America (except Puerto Rico)
  • Zone 5 is Africa
  • Zone 6 is Asia (excluding Russia, which was listed in Zone 2)

Each zone is broken down into regions, which are broken down into nets, which consist of individual nodes. Zones 7-4095 are used for "othernets"; groupings of nodes which use Fido-compatible software to carry their own independent message areas without being in any way controlled by FidoNet's political structure. Using un-used zone numbers would ensure that each network would have a unique set of addresses, avoiding potential routing conflicts and ambiguities for systems that belonged to more than one network.

FidoNet addresses[]

FidoNet addresses explicitly consist of a Zone number, a Network number (or region number), and a Node number. They are written in the form Zone:Network/Node. The FidoNet structure also allows for semantic designation of region, host, and hub status for particular nodes, but this status is not directly indicated by the main address.

For example, consider a node located in Tulsa, Oklahoma, USA with an assigned node number is 918, located in Zone 1 (North America), Region 19, and Network 170. The full FidoNet address for this system would be 1:170/918. The region was used for administrative purposes, and was only part of the address if the node was listed directly underneath the Regional Coordinator, rather than one of the networks that were used to divide the region further.

FidoNet policy requires that each FidoNet system maintain a nodelist of every other member system. Information on each node includes the name of the system or BBS, the name of the node operator, the geographic location, the telephone number, and software capabilities. The nodelist is updated weekly, to avoid unwanted calls to nodes that had shut down, with their phone numbers possibly having been reassigned for voice use by the respective telephone company.

To accomplish regular updates, coordinators of each network maintain the list of systems in their local areas. The lists are forwarded back to the International Coordinator via automated systems on a regular basis. The International Coordinator would then compile a new nodelist, and generate the list of changes (nodediff) to be distributed for node operators to apply to their existing nodelist.

Routing of FidoNet mail[]

In a theoretical situation, a node would normally forward messages to a hub. The hub, acting as a distribution point for mail, might then send the message to the Net Coordinator. From there it may be sent through a Regional Coordinator, or to some other system specifically set up for the function. Mail to other zones might be sent through a Zone Gate.

For example, a FidoNet message might follow the path:

  • 1:170/918 (node) to 1:170/900 (hub) to 1:170/0 (net coordinator) to 1:19/0 (region coordinator) to 1:1/0 (zone coordinator). From there, it was distributed 'down stream' to the destination node(s).

Part of the objective behind the formation of local nets was to implement cost reduction plans by which all messages would be sent to one or more hubs or hosts in compressed form (ARC was nominally standard, but PKZIP is universally supported); one toll call could then be made during off-peak hours to exchange entire message-filled archives with an out-of-town uplink for further redistribution.

In practice, the FidoNet structure allows for any node to connect directly to any other, and node operators would sometimes form their own toll-calling arrangements on an ad-hoc basis, allowing for a balance between collective cost saving and timely delivery. For instance, if one node operator in a network offered to make regular toll calls to a particular system elsewhere, other operators might arrange to forward all of their mail destined for the remote system, and those near it, to the local volunteer. Operators within individual networks would sometimes have cost-sharing arrangements, but it was also common for people to volunteer to pay for regular toll calls either out of generosity, or to build their status in the community.

This ad-hoc system was particularly popular with networks that were built on top of FidoNet. Echomail, for instance, often involved relatively large file transfers due to its popularity. If official FidoNet distrubutors refused to transfer Echomail due to additional toll charges, other node operators would sometimes volunteer. In such cases, Echomail messages would be routed to the volunteers' systems instead.

As the FidoNet system was best adapted to an environment in which local telephone service was inexpensive and long-distance calls (or intercity data transfer via packet-switched networks) costly, it fared somewhat poorly in countries such as Japan, where even local lines are expensive. FidoNet was only moderately successful in countries such as France, where tolls on local calls and competition with Minitel or other data networks traditionally limited its growth.


As the number of messages in Echomail grew over time, it became very difficult for users to keep up with the volume while logged into their local system. Points were introduced to address this, allowing technically savvy users to receive the already compressed and batched Echomail (and Netmail) and read it locally on their own machines.

To do this, the FidoNet addressing scheme was extended with the addition of a final address segment, the point number. For instance, a user on the example system above might be given point number 10, and thus could be sent mail at the address 1:170/918.10.

In real-world use, points are fairly difficult to set up. The FidoNet software typically consisted of a number of small utility programs run by manually-adjusted scripts. Reading and editing the mail required either a "sysop editor" or a BBS be run locally.

In North America (Zone 1) points were used only briefly, and even then only to a limited degree. Dedicated offline mail reader programs such as QWK and Blue Wave were introduced in the early 1990s, and quickly rendered the point system obsolete.

In other parts of the world, especially Europe, this was different. Contrary to North America where local calls usually are free, in Europe local calls are mostly metered and so there was an incentive to keep the duration of the calls as short as possible. Point software employs standard compression (ZIP, ARJ etc) and so keeps the calls down to a few minutes a day at most.

In Europe (Zone 2) pointing became very popular. Many regions distribute a pointlist in parallel with the nodelist. The pointlist segments are maintained by Net- and Region Pointlist Keepers and the Zone Point List Keeper assembles them into the Zone pointlist. At the peak of FidoNet there were over 120.000 points listed in the Z2 pointlist. Listing points is on a voluntary basis and not every point is listed, so how many points there really were is anybody's guess. Today (june 2006) there are still some 50.000 listed points. Most of them in Russia and Ukraine.

Technical specifications[]

FidoNet contained several technical specifications for compatibility between systems. The most basic of all was FTS-0001, with which all FidoNet systems were required to comply as a minimal requirement. FTS-0001 defined:

  • Handshaking - the protocols used by mailer software to identify each other and exchange meta information about the session.
  • Transfer protocol (XMODEM) - the protocols to be used for transferring files containing FidoNet mail between systems.
  • Message format - the standard format for FidoNet messages during the time which they were exchanged between systems.

Other specifications that were commonly used provided for echomail, different transfer protocols and handshake methods (e.g.: Yoohoo/Yoohoo2u2, EMSI), file compression, nodelist format, transfer over reliable connections such as the Internet (Binkp), and other aspects.

Zone mail hour[]

Since computer bulletin boards historically used the same telephone lines for transferring mail as were used for dial-in human users of the BBS, FidoNet policy dictates that at least one designated line of each FidoNet node must be available for accepting mail from other FidoNet nodes during a particular hour of each day.

"Zone Mail Hour", as it was named, varies depending on the geographic location of the node, and was designated to occur during the early morning. The exact hour varies depending on the time zone, and any node with only one telephone line is required to reject human callers. In practice, particularly in later times, most FidoNet systems tend to accept mail at any time of day when the phone line is not busy, usually during night.

FidoNet deployments[]

Although monolithic software that encompassed all required functions in one package was available, most FidoNet deployments were designed in a modular fashion. A typical deployment would involve several applications that would communicate through shared files and directories, and switch between each other through carefully designed scripts or batch files.

Mailer software was responsible for transferring files and messages between systems, as well as passing control to other applications, such as the BBS software, at appropriate times. The mailer would initially answer the phone and, if necessary, deal with incoming mail via FidoNet transfer protocols. If the mailer answered the phone and a human caller was detected rather than other mailer software, the mailer would exit, and pass control to the BBS software, which would then initialise for interaction with the user. When outgoing mail was waiting on the local system, the mailer software would attempt to send it from time to time by dialing and connecting to other systems who would accept and route the mail further. Due to the costs of toll calls which often varied between peak and off-peak times, mailer software would usually allow its operator to configure the optimal times in which to attempt to send mail to other systems.

BBS software was used to interact with human callers to the system. BBS software would allow dial-in users to use the system's message bases and write mail to others, locally or on other BBSes. Mail directed to other BBSes would later be routed and sent by the mailer, usually after the user had finished using the system. Many BBSes also allowed users to exchange files, play games, and interact with other users in a variety of ways (ie: node to node chat).

A scanner/tosser application, such as Squish or FastEcho, would normally be invoked when a BBS user had entered a new FidoNet message that needed to be sent, or when a mailer had received new mail to be imported into the local messages bases. This application would be responsible for handling the packaging of incoming and outgoing mail, moving it between the local system's message bases and the mailer's inbound and outbound directories. The scanner/tosser application would generally be responsible for basic routing information, determining which systems to forward mail to.

In later times, message readers that were independent of BBS software were also developed. Often the System Operator of a particular BBS would use a devoted message reader, rather than the BBS software itself, to read and write FidoNet and related messages. In some cases FidoNet nodes, or more often FidoNet points, had no public bulletin board attached, and existed only for the transfer of mail for the benefit of the node's operator.

The original Fido BBS software, and much other original FidoNet-supporting software, is no longer functional on modern systems. This is for several reasons, including problems related to the Y2K bug. In many cases, the original authors have left the BBS or shareware community, and the software, much of which was closed source, has been rendered abandonware. Alternative software had been designed to be interoperable with the same standards, however, and thus the network is still accessible.

FidoNet availability[]

While the use of FidoNet has dropped dramatically compared with its use up to the mid-1990s, it is still particularly popular in Russia. Some BBSes, including those that are now available for users with Internet connections via telnet, also retain their FidoNet netmail and echomail feeds.

Some of FidoNet's echomail conferences are available via gateways with the Usenet news hierarchy. There are also mail gates for exchanging messages between Internet and FidoNet. Widespread net abuse and e-mail spam on the Internet side has caused some gateways (such as the former 1:1/31 IEEE gateway) to become unusable or cease operation entirely.

See also[]

  • FidoNews
  • UUCP

External links[]