UUCP
Encyclopedia
UUCP is an abbreviation
Abbreviation
An abbreviation is a shortened form of a word or phrase. Usually, but not always, it consists of a letter or group of letters taken from the word or phrase...

 for Unix-to-Unix Copy. The term generally refers to a suite of computer program
Computer program
A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...

s and protocol
Communications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...

s allowing remote execution of commands and transfer of file
Computer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...

s, email
Email
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...

 and netnews between computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

s. Specifically, a command named uucp is one of the programs in the suite; it provides a user interface for requesting file copy operations. The UUCP suite also includes uux (user interface for remote command execution), uucico (the communication program that performs the file transfers), uustat (reports statistics on recent activity), uuxqt (execute commands sent from remote machines), and uuname (reports the UUCP name of the local system).

Although UUCP was originally developed on Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

 and is most closely associated with Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....

 systems, UUCP implementations exist for several non-Unix-like operating systems, including Microsoft's MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...

, Digital's VAX/VMS
OpenVMS
OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is a computer server operating system that runs on VAX, Alpha and Itanium-based families of computers. Contrary to what its name suggests, OpenVMS is not open source software; however, the source listings are available for purchase...

, Commodore's AmigaOS
AmigaOS
AmigaOS is the default native operating system of the Amiga personal computer. It was developed first by Commodore International, and initially introduced in 1985 with the Amiga 1000...

, classic Mac OS
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...

, and even CP/M
CP/M
CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...

.

Technology

UUCP can use several different types of physical connections and link layer
Link Layer
In computer networking, the link layer is the lowest layer in the Internet Protocol Suite , the networking architecture of the Internet . It is the group of methods or protocols that only operate on a host's link...

 protocols, but was most commonly used over dial-up connections. Before the widespread availability of Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

 connectivity, computers were only connected by smaller private networks within a company or organization. They were also often equipped with modems so they could be used remotely from character-mode terminals via dial-up lines. UUCP uses the computers' modems to dial out to other computers, establishing temporary, point-to-point links between them. Each system in a UUCP network has a list of neighbor systems, with phone numbers, login names and passwords, etc. When work (file transfer or command execution requests) is queued for a neighbor system, the uucico program typically calls that system to process the work. The uucico program can also poll its neighbors periodically to check for work queued on their side; this permits neighbors without dial-out capability to participate.

Today, UUCP is rarely used over dial-up links, but is occasionally used over TCP/IP
Internet protocol suite
The Internet protocol suite is the set of communications protocols used for the Internet and other similar networks. It is commonly known as TCP/IP from its most important protocols: Transmission Control Protocol and Internet Protocol , which were the first networking protocols defined in this...

.

One example of the current use of UUCP is in the retail industry by Epicor
Epicor
Epicor Software Corporation is a company selling business software to the manufacturing, distribution, retail and services industries. Epicor claims to have more than 33,000 customers in over 150 countries...

 CRS Retail Systems for transferring batch files between corporate and store systems via TCP
Transmission Control Protocol
The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...

 and dial-up on SCO OpenServer
SCO OpenServer
SCO OpenServer, previously SCO UNIX and SCO Open Desktop , is, misleadingly, a closed source version of the Unix computer operating system developed by Santa Cruz Operation and now maintained by the SCO Group....

, Red Hat Linux
Red Hat Linux
Red Hat Linux, assembled by the company Red Hat, was a popular Linux based operating system until its discontinuation in 2004.Red Hat Linux 1.0 was released on November 3, 1994...

, and Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 (with Cygwin
Cygwin
Cygwin is a Unix-like environment and command-line interface for Microsoft Windows. Cygwin provides native integration of Windows-based applications, data, and other system resources with applications, software tools, and data of the Unix-like environment...

). The number of systems involved, as of early 2006, ran between 1500 and 2000 sites across 60 enterprises. UUCP's longevity can be attributed to its low/zero cost, extensive logging, native failover
Failover
In computing, failover is automatic switching to a redundant or standby computer server, system, or network upon the failure or abnormal termination of the previously active application, server, system, or network...

 to dialup, and persistent queue management.

History

UUCP was originally written at AT&T Bell Laboratories by Mike Lesk
Mike Lesk
Michael E. Lesk is a computer programmer.In the 1960s, Michael Lesk worked for the SMART Information Retrieval System project, wrote much of its retrieval code and did many of the retrieval experiments, as well as obtaining a PhD in Chemical Physics....

. By 1978 it was in use on 82 UNIX machines inside the Bell system, primarily for software distribution. It was released in 1979 as part of Version 7 Unix
Version 7 Unix
Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix operating system. V7, released in 1979, was the last Bell Laboratories release to see widespread distribution before the commercialization of Unix by AT&T in the early 1980s...

. The original UUCP was rewritten
Rewrite (programming)
A rewrite in computer programming is the act or result of re-implementing a large portion of existing functionality without re-use of its source code. When the rewrite is not using existing code at all, it is common to speak of a rewrite from scratch...

 by AT&T researchers Peter Honeyman, David A. Nowitz, and Brian E. Redman. The rewrite is referred to as HDB or HoneyDanBer uucp, which was later enhanced, bug fixed, and repackaged as BNU UUCP ("Basic Network Utilities").

Each of these versions was distributed as proprietary software, which inspired Ian Lance Taylor to write a new free software
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...

 version from scratch in 1991.
Taylor UUCP was released under the GNU General Public License
GNU General Public License
The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....

 and became the most stable and bug free version. In particular, Taylor UUCP addressed security holes which allowed some of the original internet worm
Computer worm
A computer worm is a self-replicating malware computer program, which uses a computer network to send copies of itself to other nodes and it may do so without any user intervention. This is due to security shortcomings on the target computer. Unlike a computer virus, it does not need to attach...

s to remotely execute unexpected shell commands. Taylor UUCP also incorporates features of all previous versions of UUCP, allowing it to communicate with any other version with the greatest level of compatibility and even use similar config file formats from other versions.

UUCP was also implemented for non-UNIX
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

 operating systems, most-notably MS-DOS systems. Packages such as UUSLAVE/GNUUCP (John Gilmore, Garry Paxinos, Tim Pozar), UUPC (Drew Derbyshire) and FSUUCP (Christopher Ambler of IODesign), brought early Internet connectivity to personal computers, expanding the network beyond the interconnected university systems. FSUUCP formed the basis for many BBS
Bulletin board system
A Bulletin Board System, or BBS, is a computer system running software that allows users to connect and log in to the system using a terminal program. Once logged in, a user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging...

 packages such as Galacticomm's Major BBS
Major BBS
The Major BBS was bulletin board software developed between 1986 and 1999 by Galacticomm. In 1995 it was renamed Worldgroup Server and bundled with a user client interface program named Worldgroup Manager for Microsoft Windows...

 and Mustang Software
Mustang Software
Mustang Software, Inc. was a California-based corporation that developed telecommunications software products. Mustang was incorporated in 1988, became a public corporation in 1995, and was finally merged into Quintus Corporation in 2000.Mustang's first software products were sold using the...

's Wildcat! BBS
Wildcat! BBS
Wildcat! BBS was a bulletin board system server application that Mustang Software developed in 1986 for DOS, and later ported to Microsoft Windows. By the release of Version 4 it was the basis for more than 50,000 bulletin board systems worldwide....

 to connect to the UUCP network and exchange email and Usenet
Usenet
Usenet is a worldwide distributed Internet discussion system. It developed from the general purpose UUCP architecture of the same name.Duke University graduate students Tom Truscott and Jim Ellis conceived the idea in 1979 and it was established in 1980...

 traffic. As an example, UFGATE (John Galvin, Garry Paxinos, Tim Pozar) was a package that provided a gateway between networks running Fidonet and UUCP protocols.

FSUUCP was notable for being the only other implementation of Taylor's enhanced 'i' protocol, a significant improvement over the standard 'g' protocol used by most UUCP implementations.

UUCP for mail routing

The uucp and uuxqt capabilities could be used to send email
Email
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...

 between machines, with suitable mail user interface and delivery agent programs. A simple UUCP mail address was formed from the adjacent machine name, an exclamation mark
Exclamation mark
The exclamation mark, exclamation point, or bang, or "dembanger" is a punctuation mark usually used after an interjection or exclamation to indicate strong feelings or high volume , and often marks the end of a sentence. Example: “Watch out!” The character is encoded in Unicode at...

 or bang, followed by the user name on the adjacent machine. For example, the address barbox!user would refer to user user on adjacent machine barbox.

Mail could furthermore be routed through the network, traversing any number of intermediate nodes before arriving at its destination. Initially, this had to be done by specifying the complete path, with a list of intermediate host names separated by bangs. For example, if machine barbox is not connected to the local machine, but it is known that barbox is connected to machine foovax which does communicate with the local machine, the appropriate address to send mail to would be foovax!barbox!user.

User barbox!user might publish their UUCP email address in a form such as …!bigsite!foovax!barbox!user. This directs people to route their mail to machine bigsite (presumably a well-known and well-connected machine accessible to everybody) and from there through the machine foovax to the account of user user on barbox. Many users would suggest multiple routes from various large well-known sites, providing even better and perhaps faster connection service from the mail sender.

Bang path

An email address of this form was known as a bang path.
Bang paths of eight to ten machines (or hops) were not uncommon in 1981, and late-night dial-up UUCP links would cause week-long transmission times. Bang paths were often selected by both transmission time and reliability, as messages would often get lost. Some hosts went so far as to try to "rewrite
Rewriting
In mathematics, computer science, and logic, rewriting covers a wide range of methods of replacing subterms of a formula with other terms. What is considered are rewriting systems...

" the path, sending mail via "faster" routes—this practice tended to be frowned upon.

The "pseudo-domain" ending .uucp
.uucp
The name uucp was a pseudo-domain-style suffix used in the 1980s when identifying a hostname not connected directly to the Internet, but possibly reachable through other inter-network gateways...

was sometimes used to designate a hostname as being reachable by UUCP networking, although this was never formally in the Internet root as a top-level domain
Top-level domain
A top-level domain is one of the domains at the highest level in the hierarchical Domain Name System of the Internet. The top-level domain names are installed in the root zone of the name space. For all domains in lower levels, it is the last part of the domain name, that is, the last label of a...

. This would not have made sense anyway, because the DNS system is only appropriate for hosts reachable directly by TCP/IP. Additionally, uucp as a community administers itself and does not mesh well with the administration methods and regulations governing the DNS; .uucp works where it needs to; some hosts punt mail out of SMTP queue into uucp queues on gateway machines if a .uucp address is recognized on an incoming SMTP connection

Usenet
Usenet
Usenet is a worldwide distributed Internet discussion system. It developed from the general purpose UUCP architecture of the same name.Duke University graduate students Tom Truscott and Jim Ellis conceived the idea in 1979 and it was established in 1980...

 traffic was originally transmitted over the UUCP protocol using bang paths. These are still in use within Usenet message format Path header lines. They now have only an informational purpose, and are not used for routing, although they can be used to ensure that loops do not occur.

In general, this form of e-mail address
E-mail address
An email address identifies an email box to which email messages are delivered. An example format of an email address is lewis@example.net which is read as lewis at example dot net...

 has now been superseded by the "@ notation", even by sites still using UUCP.

UUCPNET and mapping

UUCPNET was the name for the totality of the network of computers connected through UUCP. This network was very informal, maintained in a spirit of mutual cooperation between systems owned by thousands of private companies, universities, and so on. Often, particularly in the private sector, UUCP links were established without official approval from the companies' upper management. The UUCP network was constantly changing as new systems and dial-up links were added, others were removed, etc.

The UUCP Mapping Project was a volunteer, largely successful effort to build a map of the connections between machines that were open mail relay
Open mail relay
An open mail relay is an SMTP server configured in such a way that it allows anyone on the Internet to send e-mail through it, not just mail destined to or originating from known users...

s and establish a managed namespace. Each system administrator would submit, by e-mail, a list of the systems to which theirs would connect, along with a ranking for each such connection. These submitted map entries were processed by an automatic program that combined them into a single set of files describing all connections in the network. These files were then published monthly in a newsgroup
Newsgroup
A usenet newsgroup is a repository usually within the Usenet system, for messages posted from many users in different locations. The term may be confusing to some, because it is usually a discussion group. Newsgroups are technically distinct from, but functionally similar to, discussion forums on...

 dedicated to this purpose. The UUCP map files could then be used by software such as "pathalias" to compute the best route path from one machine to another for mail, and to supply this route automatically. The UUCP maps also listed contact information for the sites, and so gave sites seeking to join UUCPNET an easy way to find prospective neighbors.

Connections with the Internet

Many UUCP hosts, particularly those at universities, were also connected to the Internet in its early years, and e-mail gateways between Internet SMTP-based mail and UUCP mail were developed. A user at a system with UUCP connections could thereby exchange mail with Internet users, and the Internet links could be used to bypass large portions of the slow UUCP network. A "UUCP zone" was defined within the Internet domain namespace to facilitate these interfaces.

With this infrastructure in place, UUCP's strength was that it permitted a site to gain Internet e-mail and Usenet connectivity with only a dial-up modem link to another cooperating computer. This was at a time when true Internet access required a leased data line
Leased line
A leased line is a service contract between a provider and a customer, whereby the provider agrees to deliver a symmetric telecommunications line connecting two or more locations in exchange for a monthly rent . It is sometimes known as a 'Private Circuit' or 'Data Line' in the UK or as CDN in Italy...

 providing a connection to an Internet Point of Presence, both of which were expensive and difficult to arrange. By contrast, a link to the UUCP network could usually be established with a few phone calls to the administrators of prospective neighbor systems. Neighbor systems were often close enough to avoid all but the most basic charges for telephone calls.

Decline

UUCP usage began to die out with the rise of ISP
Internet service provider
An Internet service provider is a company that provides access to the Internet. Access ISPs directly connect customers to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and host other people servers...

s offering inexpensive SLIP and PPP
Point-to-Point Protocol
In networking, the Point-to-Point Protocol is a data link protocol commonly used in establishing a direct connection between two networking nodes...

 services. The UUCP Mapping Project was formally shut down late in 2000.

The UUCP protocol has now mostly been replaced by the Internet TCP/IP based protocols SMTP
Simple Mail Transfer Protocol
Simple Mail Transfer Protocol is an Internet standard for electronic mail transmission across Internet Protocol networks. SMTP was first defined by RFC 821 , and last updated by RFC 5321 which includes the extended SMTP additions, and is the protocol in widespread use today...

 for mail and NNTP
Network News Transfer Protocol
The Network News Transfer Protocol is an Internet application protocol used for transporting Usenet news articles between news servers and for reading and posting articles by end user client applications...

 Usenet news.

Last uses and legacy

One surviving feature of UUCP is the chat file format, largely inherited by the expect
Expect
Expect is a Unix automation and testing tool, written by Don Libes as an extension to the Tcl scripting language, for interactive applications such as telnet, ftp, passwd, fsck, rlogin, tip, ssh, and others. It uses Unix pseudo terminals to wrap up subprocesses transparently, allowing the...

 software package.

UUCP was in use over special-purposes high cost links (e.g., marine satellite links) long after its disappearance elsewhere, and still remains in legacy use.

In the mid 2000s, UUCP over TCP/IP (often encrypted, using the SSH
Secure Shell
Secure Shell is a network protocol for secure data communication, remote shell services or command execution and other secure network services between two networked computers that it connects via a secure channel over an insecure network: a server and a client...

 protocol) was proposed for use when a computer doesn't have any fixed IP addresses but is still willing to run a standard mail transfer agent
Mail transfer agent
Within Internet message handling services , a message transfer agent or mail transfer agent or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture...

 (MTA) like Sendmail
Sendmail
Sendmail is a general purpose internetwork email routing facility that supports many kinds of mail-transfer and -delivery methods, including the Simple Mail Transfer Protocol used for email transport over the Internet....

 or Postfix
Postfix (software)
In computing, Postfix is a free and open-source mail transfer agent that routes and delivers electronic mail. It is intended as a fast, easier-to-administer, and secure alternative to the widely-used Sendmail MTA....

.

Bang paths are still in use within the Usenet
Usenet
Usenet is a worldwide distributed Internet discussion system. It developed from the general purpose UUCP architecture of the same name.Duke University graduate students Tom Truscott and Jim Ellis conceived the idea in 1979 and it was established in 1980...

 network, though not for routing; they are used to record the nodes through which a message has passed, rather than to direct where it will go next.

"Bang path" is also used as an expression for any explicitly specified routing
Routing
Routing is the process of selecting paths in a network along which to send network traffic. Routing is performed for many kinds of networks, including the telephone network , electronic data networks , and transportation networks...

 path between network hosts. That usage is not necessarly limited to uucp, IP routing, email messaging, or Usenet.

See also

  • Routing
    Routing
    Routing is the process of selecting paths in a network along which to send network traffic. Routing is performed for many kinds of networks, including the telephone network , electronic data networks , and transportation networks...

  • Sitename
  • Wizzy Digital Courier
    Wizzy Digital Courier
    Wizzy Digital Courier is a project to distribute useful data to places with no Internet connection. Primarily for e-mail, it also carries web content . From an early description of the project 1:...

    —low-cost internet delivery system using UUCP
  • FidoNet
    FidoNet
    FidoNet is a worldwide computer network that is used for communication between bulletin board systems. It was most popular in the early to mid 1990s, prior to the introduction of easy and affordable access to the Internet...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK