Product Code Database
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). Some versions of the suite include uuencode/uudecode (convert 8-bit binary files to 7-bit text format and vice versa).
Although UUCP was originally developed on Unix in the 1970s and 1980s, and is most closely associated with Unix-like systems, UUCP implementations exist for several non-Unix-like operating systems, including Microsoft's MS-DOS, IBM's OS/2, Digital's VAX/VMS, Commodore's AmigaOS, classic Mac OS, and even CP/M.
Today, UUCP is rarely used over dial-up links, but is occasionally used over TCP/IP. 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 cost, extensive logging, native failover to dialup, and persistent queue management.
Each of these versions was distributed as proprietary software, which inspired Ian Lance Taylor to write a new free software version from scratch in 1991. Taylor UUCP was released under the GNU General Public License. Taylor UUCP addressed security holes which allowed some of the original network worm to remotely execute unexpected shell commands. Taylor UUCP also incorporated features of all previous versions of UUCP, allowing it to communicate with any other version and even use similar config file formats from other versions.
UUCP was also implemented for non-UNIX 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 bulletin board system (BBS) packages such as Galacticomm's Major BBS and Mustang Software's Wildcat! BBS to connect to the UUCP network and exchange email and Usenet 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 the only other implementation of Taylor's enhanced 'i' protocol, a significant improvement over the standard 'g' protocol used by most UUCP implementations.
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 would generally 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. Publishing a full path would be pointless, because it would be different, depending on where the sender was. (e.g. Ann at one site may have to send via path gway!tcol!canty!uoh!bigsite!foovax!barbox!user, whereas from somewhere else, Bill has to send via the path pdp10!router22!bigsite!foovax!barbox!user). Many users would suggest multiple routes from various large well-known sites, providing even better and perhaps faster connection service from the mail sender.
The "pseudo-domain" ending .uucp was sometimes used to designate a hostname as being reachable by UUCP networking, although this was never formally registered in the domain name system (DNS) as a top-level domain. The uucp community administered itself and did 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 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 has now been superseded by the "@ notation", even by sites still using UUCP. A UUCP-only site can register a DNS domain name, and have the DNS server that handles that domain provide that cause Internet mail to that site to be delivered to a UUCP host on the Internet that can then deliver the mail to the UUCP site.
The UUCP Mapping Project was a volunteer, largely successful effort to build a map of the connections between machines that were 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 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.
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 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.
The UUCP protocol has now mostly been replaced by the Internet TCP/IP based protocols SMTP for mail and NNTP for Usenet news.
In July 2012, Dutch Internet provider XS4ALL closed down its UUCP service, claiming it was "probably one of the last providers in the world that still offered it"; it had only 13 users at that time (however prior to its shut-down it had refused requests from new users for several years).
UUCP was in use over special-purpose 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 protocol) was proposed for use when a computer does not have any fixed IP addresses but is still willing to run a standard mail transfer agent (MTA) like Sendmail or Postfix.
Bang paths are still in use within the Usenet 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 path between network hosts. That usage is not necessarily limited to UUCP, IP routing, email messaging, or Usenet.
The concept of delay-tolerant networking protocols was revisited in the early 2000s. Similar techniques as those used by UUCP can apply to other networks that experience delay or significant disruption. ξ1
See also
External links
References
|
|
