Early research and development:
129-589: Early research and development: Merging the networks and creating the Internet: Commercialization, privatization, broader access leads to the modern Internet: Examples of Internet services: Usenet ( / ˈ j uː z n ɛ t / ), USENET , or, "in full", User's Network , is a worldwide distributed discussion system available on computers. It was developed from the general-purpose Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Ellis conceived
258-756: A protocol stack , often constructed per the OSI model, communications functions are divided up into protocol layers, where each layer leverages the services of the layer below it until the lowest layer controls the hardware that sends information across the media. The use of protocol layering is ubiquitous across the field of computer networking. An important example of a protocol stack is HTTP (the World Wide Web protocol) running over TCP over IP (the Internet protocols) over IEEE 802.11 (the Wi-Fi protocol). This stack
387-524: A 16-bit checksum of the payload, not including the header. The next byte is the data type and finally, the last byte is the XOR of the header, allowing it to be checked separately from the payload. The control byte consists of three bit-fields in the format TTXXXYYY. TT is the packet type, 0 for control packets (which also requires K=9 to be valid), 1 for alternate data (not used in UUCP), 2 for data, and 3 indicates
516-597: A charter, a rationale, and a moderation policy if the group is to be moderated. Discussion of the new newsgroup proposal follows, and is finished with the members of the Big-8 Management Board making the decision, by vote, to either approve or disapprove the new newsgroup. Unmoderated newsgroups form the majority of Usenet newsgroups, and messages submitted by readers for unmoderated newsgroups are immediately propagated for everyone to see. Minimal editorial content filtering vs propagation speed form one crux of
645-602: A cross post to the *.answers group at the head of the hierarchy seen by some as a refining of information in that news group. Some subgroups are recursive—to the point of some silliness in alt.* . Usenet was originally created to distribute text content encoded in the 7- bit ASCII character set. With the help of programs that encode 8-bit values into ASCII, it became practical to distribute binary files as content. Binary posts, due to their size and often-dubious copyright status, were in time restricted to specific newsgroups, making it easier for administrators to allow or disallow
774-457: A disproportionately high volume of customer support incidents (frequently complaining of missing news articles). Some ISPs outsource news operations to specialist sites, which will usually appear to a user as though the ISP itself runs the server. Many of these sites carry a restricted newsfeed, with a limited number of newsgroups. Commonly omitted from such a newsfeed are foreign-language newsgroups and
903-503: A diverse set of networking capabilities. The protocols have a flat addressing scheme. They operate mostly at layers 1 and 2 of the OSI model. For example, MAC bridging ( IEEE 802.1D ) deals with the routing of Ethernet packets using a Spanning Tree Protocol . IEEE 802.1Q describes VLANs , and IEEE 802.1X defines a port-based network access control protocol, which forms the basis for the authentication mechanisms used in VLANs (but it
1032-500: 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. uux is remote command execution over UUCP. The uux command is used to execute a command on a remote system , or to execute a command on the local system using files from remote systems. The command is run by the uucico daemon, which handles remote execution requests as simply another kind of file to batch-send to
1161-529: 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
1290-440: A large, congested network into an aggregation of smaller, more efficient networks. A router is an internetworking device that forwards packets between networks by processing the addressing or routing information included in the packet. The routing information is often processed in conjunction with the routing table . A router uses its routing table to determine where to forward packets and does not require broadcasting packets which
1419-575: A moderator must bear the Approved: header line. Moderators ensure that the messages that readers see in the newsgroup conform to the charter of the newsgroup, though they are not required to follow any such rules or guidelines. Typically, moderators are appointed in the proposal for the newsgroup, and changes of moderators follow a succession plan. Historically, a mod.* hierarchy existed before Usenet reorganization. Now, moderated newsgroups may appear in any hierarchy, typically with .moderated added to
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#17327810623411548-440: A multi-port bridge. Switches normally have numerous ports, facilitating a star topology for devices, and for cascading additional switches. Bridges and switches operate at the data link layer (layer 2) of the OSI model and bridge traffic between two or more network segments to form a single local network. Both are devices that forward frames of data between ports based on the destination MAC address in each frame. They learn
1677-499: A news server might attempt to control the spread of spam by refusing to accept or forward any posts that trigger spam filters , or a server without high-capacity data storage may refuse to carry any newsgroups used primarily for file sharing , limiting itself to discussion-oriented groups. However, unlike BBSes and web forums, the dispersed nature of Usenet usually permits users who are interested in receiving some content to access it simply by choosing to connect to news servers that carry
1806-687: A newsgroup under the Big Eight which contains discussions about children's books, but a group in the alt hierarchy may be dedicated to one specific author of children's books. Binaries are posted in alt.binaries.* , making it the largest of all the hierarchies. Many other hierarchies of newsgroups are distributed alongside these. Regional and language-specific hierarchies such as japan.* , malta.* and ne.* serve specific countries and regions such as Japan , Malta and New England . Companies and projects administer their own hierarchies to discuss their products and offer community technical support, such as
1935-517: A number of new link layer protocols. These newer connections also reduced the need for UUCP at all, as newer application protocols developed to take advantage of the new networks. 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. UUCP
2064-412: A readership which is potentially widely distributed. These protocols most commonly use a flooding algorithm which propagates copies throughout a network of participating servers. Whenever a message reaches a server, that server forwards the message to all its network neighbors that haven't yet seen the article. Only one copy of a message is stored per server, and each server makes it available on demand to
2193-457: A repeater hub assists with collision detection and fault isolation for the network. Hubs and repeaters in LANs have been largely obsoleted by modern network switches. Network bridges and network switches are distinct from a hub in that they only forward frames to the ports involved in the communication whereas a hub forwards to all ports. Bridges only have two ports but a switch can be thought of as
2322-476: A series of file requests. There are four types: After sending an H command, the calling system sends a final packet \20OOOOOO\0 (control-P, six ohs, null-terminator) and the called system responds with \20OOOOOO\0 (control-P, seven ohs, null-terminator). Some systems will simply hang up on the successful reception of the H command and not bother with the final handshake. Within the suite of protocols in UUCP,
2451-426: A server is high but the storage allocation is small, it is possible for a huge flood of incoming content to overflow the allocation and push out everything that was in the group before it. The average length of time that posts are able to stay on the server before being deleted is commonly called the retention time . Binary newsgroups are only able to function reliably if there is sufficient storage allocated to handle
2580-646: A server, just (local) telephone service. The name Usenet comes from the term "users' network". The first Usenet group was NET.general , which quickly became net.general . The first commercial spam on Usenet was from immigration attorneys Canter and Siegel advertising green card services. On the Internet, Usenet is transported via the Network News Transfer Protocol (NNTP) on Transmission Control Protocol (TCP) port 119 for standard, unprotected connections, and on TCP port 563 for Secure Sockets Layer (SSL) encrypted connections. Usenet
2709-404: A short packet that re-defines the meaning of K. In a data packet, XXX is the packet number for this packet from 0 to 7, and YYY is the last that was received correctly. This provides up to 8 packets in a window. In a control packet, XXX indicates the command and YYY is used for various parameters. For instance, transfers are started by sending a short control packet with TT=0 (control), XXX=7 and YYY
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#17327810623412838-418: A single failure can cause the network to fail entirely. In general, the more interconnections there are, the more robust the network is; but the more expensive it is to install. Therefore, most network diagrams are arranged by their network topology which is the map of logical interconnections of network hosts. Common topologies are: The physical layout of the nodes in a network may not necessarily reflect
2967-609: 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. Many UUCP hosts, particularly those at universities, were also connected to
3096-403: A standard voice telephone line. Modems are still commonly used for telephone lines, using a digital subscriber line technology and cable television systems using DOCSIS technology. A firewall is a network device or software for controlling network security and access rules. Firewalls are inserted in connections between secure internal networks and potentially insecure external networks such as
3225-746: A system using 4k packets and 7 packet windows (4096x7) would offer performance matching or beating the best file-transfer protocols like ZMODEM . In practice, many implementations only supported a single setting of 64x3. As a result, the g-protocol has an undeserved reputation for poor performance. Confusion over the packet and window sizes led to the G-protocol, differing only in that it always used 4096x3. Taylor UUCP did not support G, but did support any valid requested window or packet size, so remote systems starting G would work fine with Taylor's g, while two Taylor systems could negotiate even faster connections. Telebit modems used protocol spoofing to improve
3354-456: A takedown petition to be most effective across the whole network, it would have to be issued to the origin server to which the content has been posted, before it has been propagated to other servers. Removal of the content at this early stage would prevent further propagation, but with modern high speed links, content can be propagated as fast as it arrives, allowing no time for content review and takedown issuance by copyright holders. Establishing
3483-553: A telecommunications service, and assert that they are not responsible for the user-posted binary content transferred via their equipment. In the United States, Usenet providers can qualify for protection under the DMCA Safe Harbor regulations , provided that they establish a mechanism to comply with and respond to takedown notices from copyright holders. Removal of copyrighted content from the entire Usenet network
3612-877: A transmission medium. Power line communication uses a building's power cabling to transmit data. The following classes of wired technologies are used in computer networking. Network connections can be established wirelessly using radio or other electromagnetic means of communication. The last two cases have a large round-trip delay time , which gives slow two-way communication but does not prevent sending large amounts of information (they can have high throughput). Apart from any physical transmission media, networks are built from additional basic system building blocks, such as network interface controllers , repeaters , hubs , bridges , switches , routers , modems, and firewalls . Any particular piece of equipment will frequently contain multiple building blocks and so may perform multiple functions. A network interface controller (NIC)
3741-418: A tree-like form. When a user posts an article, it is initially only available on that user's news server. Each news server talks to one or more other servers (its "newsfeeds") and exchanges articles with them. In this fashion, the article is copied from server to server and should eventually reach every server in the network. The later peer-to-peer networks operate on a similar principle, but for Usenet it
3870-406: A variety of network topologies . The nodes of a computer network can include personal computers , servers , networking hardware , or other specialized or general-purpose hosts . They are identified by network addresses and may have hostnames . Hostnames serve as memorable labels for the nodes and are rarely changed after initial assignment. Network addresses serve for locating and identifying
3999-495: A variety of different sources, primarily to support circuit-switched digital telephony . However, due to its protocol neutrality and transport-oriented features, SONET/SDH also was the obvious choice for transporting Asynchronous Transfer Mode (ATM) frames. Asynchronous Transfer Mode (ATM) is a switching technique for telecommunication networks. It uses asynchronous time-division multiplexing and encodes data into small, fixed-sized cells . This differs from other protocols such as
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4128-657: A virtual system of links that run on top of the Internet . Overlay networks have been used since the early days of networking, back when computers were connected via telephone lines using modems, even before data networks were developed. The most striking example of an overlay network is the Internet itself. The Internet itself was initially built as an overlay on the telephone network . Even today, each Internet node can communicate with virtually any other through an underlying mesh of sub-networks of wildly different topologies and technologies. Address resolution and routing are
4257-522: Is computer hardware that connects the computer to the network media and has the ability to process low-level network information. For example, the NIC may have a connector for plugging in a cable, or an aerial for wireless transmission and reception, and the associated circuitry. In Ethernet networks, each NIC has a unique Media Access Control (MAC) address —usually stored in the controller's permanent memory. To avoid address conflicts between network devices,
4386-466: Is a nearly impossible task, due to the rapid propagation between servers and the retention done by each server. Petitioning a Usenet provider for removal only removes it from that one server's retention cache, but not any others. It is possible for a special post cancellation message to be distributed to remove it from all servers, but many providers ignore cancel messages by standard policy, because they can be easily falsified and submitted by anyone. For
4515-422: Is a virtual network that is built on top of another network. Nodes in the overlay network are connected by virtual or logical links. Each link corresponds to a path, perhaps through many physical links, in the underlying network. The topology of the overlay network may (and often does) differ from that of the underlying one. For example, many peer-to-peer networks are overlay networks. They are organized as nodes of
4644-566: Is also found in WLANs ) – it is what the home user sees when the user has to enter a "wireless access key". Ethernet is a family of technologies used in wired LANs. It is described by a set of standards together called IEEE 802.3 published by the Institute of Electrical and Electronics Engineers. Wireless LAN based on the IEEE 802.11 standards, also widely known as WLAN or WiFi, is probably
4773-478: Is an electronic device that receives a network signal , cleans it of unnecessary noise and regenerates it. The signal is retransmitted at a higher power level, or to the other side of obstruction so that the signal can cover longer distances without degradation. In most twisted-pair Ethernet configurations, repeaters are required for cable that runs longer than 100 meters. With fiber optics, repeaters can be tens or even hundreds of kilometers apart. Repeaters work on
4902-490: Is connecting to it. Some Usenet providers do keep usage logs, but not all make this logged information casually available to outside parties such as the Recording Industry Association of America . The existence of anonymising gateways to USENET also complicates the tracing of a postings true origin. Bruce Jones, Henry Spencer , David Wiseman. Copied with permission from UUCP Merging
5031-403: Is contained within nine hierarchies, eight of which are operated under consensual guidelines that govern their administration and naming. The current Big Eight are: The alt.* hierarchy is not subject to the procedures controlling groups in the Big Eight, and it is as a result less organized. Groups in the alt.* hierarchy tend to be more specialized or specific—for example, there might be
5160-412: Is inefficient for very big networks. Modems (modulator-demodulator) are used to connect network nodes via wire not originally designed for digital network traffic, or for wireless. To do this one or more carrier signals are modulated by the digital signal to produce an analog signal that can be tailored to give the required properties for transmission. Early modems modulated audio signals sent over
5289-461: Is normally started by having a user log into the target system and then running the UUCP program. In most cases, this is automated by logging into a known user account used for transfers, whose account's shell has been set to uucico . Thus, for automated transfers, another machine simply has to open a modem connection to the called machine and log into the known account. When uucico runs, it will expect to receive commands from another UUCP program on
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5418-503: Is normally the sender, rather than the receiver, who initiates transfers. Usenet was designed under conditions when networks were much slower and not always available. Many sites on the original Usenet network would connect only once or twice a day to batch-transfer messages in and out. This is largely because the POTS network was typically used for transfers, and phone charges were lower at night. The format and transmission of Usenet articles
5547-404: Is not sending packets, the link can be filled with packets from other users, and so the cost can be shared, with relatively little interference, provided the link is not overused. Often the route a packet needs to take through a network is not immediately available. In that case, the packet is queued and waits until a link is free. The physical link technologies of packet networks typically limit
5676-475: Is one such web based front end and some web browsers can access Google Groups via news: protocol links directly. A minority of newsgroups are moderated, meaning that messages submitted by readers are not distributed directly to Usenet, but instead are emailed to the moderators of the newsgroup for approval. The moderator is to receive submitted articles, review them, and inject approved articles so that they can be properly propagated worldwide. Articles approved by
5805-490: Is similar to that of Internet e-mail messages. The difference between the two is that Usenet articles can be read by any user whose news server carries the group to which the message was posted, as opposed to email messages, which have one or more specific recipients. Today, Usenet has diminished in importance with respect to Internet forums , blogs , mailing lists and social media . Usenet differs from such media in several ways: Usenet requires no personal registration with
5934-629: Is the chat file format, largely inherited by the Expect software package. 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 addition to legacy use, in 2021 new and innovative UUCP uses are growing, especially for telecommunications in the HF band, for example, for communities in the Amazon rainforest for email exchange and other uses. A patch to Ian's UUCP
6063-459: Is used between the wireless router and the home user's personal computer when the user is surfing the web. There are many communication protocols, a few of which are described below. The Internet protocol suite , also called TCP/IP, is the foundation of all modern networking. It offers connection-less and connection-oriented services over an inherently unreliable network traversed by datagram transmission using Internet protocol (IP). At its core,
6192-500: The alt.binaries hierarchy which largely carries software, music, videos and images, and accounts for over 99 percent of article data. There are also Usenet providers that offer a full unrestricted service to users whose ISPs do not carry news, or that carry a restricted feed. Newsgroups are typically accessed with newsreaders : applications that allow users to read and reply to postings in newsgroups. These applications act as clients to one or more news servers. Historically, Usenet
6321-462: The Institute of Electrical and Electronics Engineers (IEEE) maintains and administers MAC address uniqueness. The size of an Ethernet MAC address is six octets . The three most significant octets are reserved to identify NIC manufacturers. These manufacturers, using only their assigned prefixes, uniquely assign the three least-significant octets of every Ethernet interface they produce. A repeater
6450-446: 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
6579-496: The Usenet network, though not for routing; they are used to record, in the header of a message, the nodes through which that 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
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#17327810623416708-477: The World Wide Web , digital video and audio , shared use of application and storage servers , printers and fax machines , and use of email and instant messaging applications. Computer networking may be considered a branch of computer science , computer engineering , and telecommunications , since it relies on the theoretical and practical application of the related disciplines. Computer networking
6837-424: The sci.* hierarchy. Or, talk.origins and talk.atheism are in the talk.* hierarchy. When a user subscribes to a newsgroup, the news client software keeps track of which articles that user has read. In most newsgroups, the majority of the articles are responses to some other article. The set of articles that can be traced to one single non-reply article is called a thread . Most modern newsreaders display
6966-461: 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 MX records 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. UUCPNET was the name for the totality of the network of computers connected through UUCP. This network
7095-452: The (typically local) readers able to access that server. The collection of Usenet servers has thus a certain peer-to-peer character in that they share resources by exchanging them, the granularity of exchange however is on a different scale than a modern peer-to-peer system and this characteristic excludes the actual users of the system who connect to the news servers with a typical client-server application, much like an email reader. RFC 850
7224-628: 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, like other older e-mail address formats , bang paths have now been superseded by
7353-440: The Internet protocol suite or Ethernet that use variable-sized packets or frames . ATM has similarities with both circuit and packet switched networking. This makes it a good choice for a network that must handle both traditional high-throughput data traffic, and real-time, low-latency content such as voice and video. ATM uses a connection-oriented model in which a virtual circuit must be established between two endpoints before
7482-574: The Internet. Firewalls are typically configured to reject access requests from unrecognized sources while allowing actions from recognized ones. The vital role firewalls play in network security grows in parallel with the constant increase in cyber attacks . A communication protocol is a set of rules for exchanging information over a network. Communication protocols have various characteristics. They may be connection-oriented or connectionless , they may use circuit mode or packet switching, and they may use hierarchical addressing or flat addressing. In
7611-405: The UUCP stack. The packet format consisted of a 6-byte header and then between zero and 4096 bytes in the payload. The packet starts with a single \020 (control-P). This is followed by a single byte, known as "K", containing a value of 1 to 8 indicating a packet size from 32 to 4096 bytes, or a 9 indicating a control packet. Many systems only supported K=2, meaning 64 bytes. The next two bytes were
7740-502: The Usenet community. One little cited defense of propagation is canceling a propagated message, but few Usenet users use this command and some news readers do not offer cancellation commands , in part because article storage expires in relatively short order anyway. Almost all unmoderated Usenet groups tend to receive large amounts of spam . Usenet is a set of protocols for generating, storing and retrieving news "articles" (which resemble Internet mail messages) and for exchanging them among
7869-627: The actual data exchange begins. ATM still plays a role in the last mile , which is the connection between an Internet service provider and the home user. There are a number of different digital cellular standards, including: Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), cdmaOne , CDMA2000 , Evolution-Data Optimized (EV-DO), Enhanced Data Rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), Digital Enhanced Cordless Telecommunications (DECT), Digital AMPS (IS-136/TDMA), and Integrated Digital Enhanced Network (iDEN). Routing
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#17327810623417998-406: The adjacent machine name, an exclamation mark (often pronounced 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
8127-671: The amount of articles being added. Without sufficient retention time, a reader will be unable to download all parts of the binary before it is flushed out of the group's storage allocation. This was at one time how posting undesired content was countered; the newsgroup would be flooded with random garbage data posts, of sufficient quantity to push out all the content to be suppressed. This has been compensated by service providers allocating enough storage to retain everything posted each day, including spam floods, without deleting anything. Modern Usenet news servers have enough capacity to archive years of binary content even when flooded with new data at
8256-400: The articles arranged into threads and subthreads. For example, in the wine-making newsgroup rec.crafts.winemaking, someone might start a thread called; "What's the best yeast?" and that thread or conversation might grow into dozens of replies long, by perhaps six or eight different authors. Over several days, that conversation about different wine yeasts might branch into several sub-threads in
8385-468: The association of physical ports to MAC addresses by examining the source addresses of received frames and only forward the frame when necessary. If an unknown destination MAC is targeted, the device broadcasts the request to all ports except the source, and discovers the location from the reply. Bridges and switches divide the network's collision domain but maintain a single broadcast domain. Network segmentation through bridging and switching helps break down
8514-432: The caller's machine and begin a session. The session has three distinct stages: On starting, uucico will respond by sending an identification string, \20Shere= hostname \0 , where \20 is the control-P character, and \0 is a trailing null. The caller's UUCP responds with \20S callername options \0 , where options is a string containing zero or more Unix-like option switches. These can include packet and window sizes,
8643-404: 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
8772-642: 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. Over time, dial-up links were replaced by Internet connections, and UUCP added
8901-416: The distribution of the data; the files are automatically disseminated to all Usenet providers exchanging data for the news group it is posted to. In general the user must manually select, prepare and upload the data. The data is typically encrypted because it is available to anyone to download the backup files. After the files are uploaded, having multiple copies spread to different geographical regions around
9030-492: The entire file is sent as a single long string followed by a whole-file checksum. The similar x-protocol appears to have seen little or no use. d-protocol was similar to x, but intended for use on Datakit networks that connected many of Bell Labs offices. t-protocol originated in the BSD versions of UUCP and like some similar ones, is designed to run over 8-bit error-free TCP/IP links. It has no error correction at all, and
9159-473: The feeds they want. Usenet is culturally and historically significant in the networked world, having given rise to, or popularized, many widely recognized concepts and terms such as " FAQ ", " flame ", " sockpuppet ", and " spam ". In the early 1990s, shortly before access to the Internet became commonly affordable, Usenet connections via FidoNet 's dial-up BBS networks made long-distance or worldwide discussions and other communication widespread, not needing
9288-433: The files reaches a server. Binary newsgroups can be used to distribute files, and, as of 2022, some remain popular as an alternative to BitTorrent to share and download files. Each news server allocates a certain amount of storage space for content in each newsgroup. When this storage has been filled, each time a new post arrives, old posts are deleted to make room for the new content. If the network bandwidth available to
9417-737: The group concerned; information need not be stored on a remote server; archives are always available; and reading the messages does not require a mail or web client, but a news client. However, it is now possible to read and participate in Usenet newsgroups to a large degree using ordinary web browsers since most newsgroups are now copied to several web sites. The groups in alt.binaries are still widely used for data transfer. Many Internet service providers, and many other Internet sites, operate news servers for their users to access. ISPs that do not operate their own servers directly will often offer their users an account from another provider that specifically operates newsfeeds. In early news implementations,
9546-480: The group name. Usenet newsgroups in the Big-8 hierarchy are created by proposals called a Request for Discussion, or RFD. The RFD is required to have the following information: newsgroup name, checkgroups file entry, and moderated or unmoderated status. If the group is to be moderated, then at least one moderator with a valid email address must be provided. Other information which is beneficial but not required includes:
9675-683: The historical gnu.* hierarchy from the Free Software Foundation . Microsoft closed its newsserver in June 2010, providing support for its products over forums now. Some users prefer to use the term "Usenet" to refer only to the Big Eight hierarchies; others include alt.* as well. The more general term "netnews" incorporates the entire medium, including private organizational news systems. Informal sub-hierarchy conventions also exist. *.answers are typically moderated cross-post groups for FAQs. An FAQ would be posted within one group and
9804-424: The idea in 1979, and it was established in 1980. Users read and post messages (called articles or posts , and collectively termed news ) to one or more topic categories, known as newsgroups . Usenet resembles a bulletin board system (BBS) in many respects and is the precursor to the Internet forums that have become widely used. Discussions are threaded , as with web forums and BBSes, though posts are stored on
9933-619: The identity of the person posting illegal content is equally difficult due to the trust-based design of the network. Like SMTP email, servers generally assume the header and origin information in a post is true and accurate. However, as in SMTP email, Usenet post headers are easily falsified so as to obscure the true identity and location of the message source. In this manner, Usenet is significantly different from modern P2P services; most P2P users distributing content are typically immediately identifiable to all other users by their network address , but
10062-668: The literature as the physical medium ) used to link devices to form a computer network include electrical cable , optical fiber , and free space. In the OSI model , the software to handle the media is defined at layers 1 and 2 — the physical layer and the data link layer. A widely adopted family that uses copper and fiber media in local area network (LAN) technology are collectively known as Ethernet. The media and protocol standards that enable communication between networked devices over Ethernet are defined by IEEE 802.3 . Wireless LAN standards use radio waves , others use infrared signals as
10191-435: The local one, while the local server will receive any news its peers have that it currently lacks. This results in the automatic proliferation of content posted by any user on any server to any other user subscribed to the same newsgroups on other servers. As with BBSes and message boards, individual news servers or service providers are under no obligation to carry any specific content, and may refuse to do so for many reasons:
10320-674: The manual deletion of infringing material using the provisions of World Intellectual Property Organization treaty implementations, such as the United States Online Copyright Infringement Liability Limitation Act , but this would require giving notice to each individual news server administrator. On the Internet, Usenet is transported via the Network News Transfer Protocol (NNTP) on TCP Port 119 for standard, unprotected connections and on TCP port 563 for SSL encrypted connections. The major set of worldwide newsgroups
10449-406: The maximum daily speed available. In part because of such long retention times, as well as growing Internet upload speeds, Usenet is also used by individual users to store backup data. While commercial providers offer easier to use online backup services , storing data on Usenet is free of charge (although access to Usenet itself may not be). The method requires the uploader to cede control over
10578-480: The maximum supported file size, debugging options, and others. Depending on the setup of the two systems, the call may end here. For instance, when the caller responds with their system name, the called system may optionally hang up if it does not recognize the caller, sending the RYou are unknown to me\0 response string and then disconnecting. If the two systems successfully handshake, the caller will now begin to send
10707-665: The means that allow mapping of a fully connected IP overlay network to its underlying network. Another example of an overlay network is a distributed hash table , which maps keys to nodes in the network. In this case, the underlying network is an IP network, and the overlay network is a table (actually a map ) indexed by keys. Overlay networks have also been proposed as a way to improve Internet routing, such as through quality of service guarantees achieve higher-quality streaming media . Previous proposals such as IntServ , DiffServ , and IP multicast have not seen wide acceptance largely because they require modification of all routers in
10836-415: The most well-known member of the IEEE 802 protocol family for home users today. IEEE 802.11 shares many properties with wired Ethernet. Synchronous optical networking (SONET) and Synchronous Digital Hierarchy (SDH) are standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber using lasers. They were originally designed to transport circuit mode communications from
10965-440: 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
11094-412: The network needs to deliver the user data, for example, source and destination network addresses , error detection codes, and sequencing information. Typically, control information is found in packet headers and trailers , with payload data in between. With packets, the bandwidth of the transmission medium can be better shared among users than if the network were circuit switched . When one user
11223-420: The network topology. As an example, with FDDI , the network topology is a ring, but the physical topology is often a star, because all neighboring connections can be routed via a central physical location. Physical layout is not completely irrelevant, however, as common ducting and equipment locations can represent single points of failure due to issues like fires, power failures and flooding. An overlay network
11352-729: The network. On the other hand, an overlay network can be incrementally deployed on end-hosts running the overlay protocol software, without cooperation from Internet service providers . The overlay network has no control over how packets are routed in the underlying network between two overlay nodes, but it can control, for example, the sequence of overlay nodes that a message traverses before it reaches its destination . For example, Akamai Technologies manages an overlay network that provides reliable, efficient content delivery (a kind of multicast ). Academic research includes end system multicast, resilient routing and quality of service studies, among others. The transmission media (often referred to in
11481-404: The networks and creating the Internet: Commercialization, privatization, broader access leads to the modern Internet: Examples of Internet services: UUCP ( Unix-to-Unix Copy ) is a suite of computer programs and protocols allowing remote execution of commands and transfer of files , email and netnews between computers . A command named uucp is one of the programs in
11610-459: The newly developed news software such as A News . The name "Usenet" emphasizes its creators' hope that the USENIX organization would take an active role in its operation. The articles that users post to Usenet are organized into topical categories known as newsgroups , which are themselves logically organized into hierarchies of subjects. For instance, sci.math and sci.physics are within
11739-494: The nodes by communication protocols such as the Internet Protocol . Computer networks may be classified by many criteria, including the transmission medium used to carry signals, bandwidth , communications protocols to organize network traffic , the network size, the topology, traffic control mechanisms, and organizational intent. Computer networks support many applications and services , such as access to
11868-473: The number of packets in a window, then sending another packet with XXX=6 and YYY as the packet length (encoded as it would be in K) and then a third packet that is identical to the first but XXX=5. g-protocol uses a simple sliding window system to deal with potentially long latencies between endpoints. The protocol allows packets to size from 64 to 4096 8-bit bytes, and windows that include 1 to 7 packets. In theory,
11997-411: The origin information for a Usenet posting can be completely obscured and unobtainable once it has propagated past the original server. Also unlike modern P2P services, the identity of the downloaders is hidden from view. On P2P services a downloader is identifiable to all others by their network address. On Usenet, the downloader connects directly to a server, and only the server knows the address of who
12126-582: 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. 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 could 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 "
12255-427: The path, sending mail via "faster" routes—this practice tended to be frowned upon. 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
12384-402: The performance of g-protocol transfers by noticing end-of-packet markers being sent to the remote system and immediately sending an ACK back to the local host, pretending that the remote system had already received the packet and decoded it correctly. This triggered the software stack to send the next packet, so rapidly that the transfer became almost continuous. The data between the two modems
12513-520: The physical layer of the OSI model but still require a small amount of time to regenerate the signal. This can cause a propagation delay that affects network performance and may affect proper function. As a result, many network architectures limit the number of repeaters used in a network, e.g., the Ethernet 5-4-3 rule . An Ethernet repeater with multiple ports is known as an Ethernet hub . In addition to reconditioning and distributing network signals,
12642-414: The protocol consists simply of breaking up command and file data into 512 or 1024-byte packets to easily fit within typical TCP frames. e-protocol ("e" for Ethernet) was developed by Clem Cole at MASSCOMP and was widely released by Brian Redman in the later HoneyDanBer versions. It was developed and released before the t-protocol, but the t-protocol was more commonly used because the BSD version of UUCP
12771-456: The protocol suite defines the addressing, identification, and routing specifications for Internet Protocol Version 4 (IPv4) and for IPv6 , the next generation of the protocol with a much enlarged addressing capability. The Internet protocol suite is the defining set of protocols for the Internet. IEEE 802 is a family of IEEE standards dealing with local area networks and metropolitan area networks. The complete IEEE 802 protocol suite provides
12900-510: The remote system whenever a next-hop node is available. The remote system will then execute the requested command and return the result, when the original system is available. Both of these transfers may be indirect, via multi-hop paths, with arbitrary windows of availability. Even when executing a command on an always-available neighbor, uux is not instant. UUCP usage began to die out with the rise of Internet service providers offering inexpensive SLIP and PPP services. The UUCP Mapping Project
13029-425: The rise of the World Wide Web (WWW), web front-ends (web2news) have become more common. Web front ends have lowered the technical entry barrier requirements to that of one application and no Usenet NNTP server account. There are numerous websites now offering web based gateways to Usenet groups, although some people have begun filtering messages made by some of the web interfaces for one reason or another. Google Groups
13158-434: The server and newsreader were a single program suite, running on the same system. Today, one uses separate newsreader client software, a program that resembles an email client but accesses Usenet servers instead. Not all ISPs run news servers. A news server is one of the most difficult Internet services to administer because of the large amount of data involved, small customer base (compared to mainstream Internet service), and
13287-542: The server sequentially. A major difference between a BBS or web message board and Usenet is the absence of a central server and dedicated administrator or hosting provider. Usenet is distributed among a large, constantly changing set of news servers that store and forward messages to one another via "news feeds". Individual users may read messages from and post to a local (or simply preferred) news server, which can be operated by anyone, and those posts will automatically be forwarded to any other news servers peered with
13416-515: The sharing of files and information, giving authorized users access to data stored on other computers. Distributed computing leverages resources from multiple computers across a network to perform tasks collaboratively. Most modern computer networks use protocols based on packet-mode transmission. A network packet is a formatted unit of data carried by a packet-switched network . Packets consist of two types of data: control information and user data (payload). The control information provides data
13545-493: The size of packets to a certain maximum transmission unit (MTU). A longer message may be fragmented before it is transferred and once the packets arrive, they are reassembled to construct the original message. The physical or geographic locations of network nodes and links generally have relatively little effect on a network, but the topology of interconnections of a network can significantly affect its throughput and reliability. With many technologies, such as bus or star networks,
13674-436: The speed of a 2400 bit/s modem. They were widely used on UUCP hosts as they could quickly pay for themselves in reduced long-distance charges. UUCP implementations also include other transfer protocols for use over certain links. f-protocol is designed to run over 7-bit error-corrected links. This was originally intended for use on X.25 links, which were popular for a time in the 1980s. It does not packetize data, instead,
13803-429: 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 DOS , OS/2 , OpenVMS (for VAX hardware only), AmigaOS , classic Mac OS , and even CP/M . UUCP
13932-420: 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
14061-516: The traffic. The oldest widely used encoding method for binary content is uuencode , from the Unix UUCP package. In the late 1980s, Usenet articles were often limited to 60,000 characters, and larger hard limits exist today. Files are therefore commonly split into sections that require reassembly by the reader. With the header extensions and the Base64 and Quoted-Printable MIME encodings, there
14190-497: The underlying g-protocol is responsible for transferring information in an error-free form. The protocol originated as a general-purpose system for packet delivery, and thus offers a number of features that are not used by the UUCP package as a whole. These include a secondary channel that can send command data interspersed with a file transfer, and the ability to renegotiate the packet and window sizes during transmission. These extra features may not be available in some implementations of
14319-899: The world on different news servers decreases the chances of data loss. Major Usenet service providers have a retention time of more than 12 years. This results in more than 60 petabytes (60000 terabytes ) of storage (see image). When using Usenet for data storage, providers that offer longer retention time are preferred to ensure the data will survive for longer periods of time compared to services with lower retention time. While binary newsgroups can be used to distribute completely legal user-created works, free software , and public domain material, some binary groups are used to illegally distribute proprietary software , copyrighted media, and pornographic material. ISP-operated Usenet servers frequently block access to all alt.binaries.* groups to both reduce network traffic and to avoid related legal issues. Commercial Usenet service providers claim to operate as
14448-437: Was rewritten by AT&T researchers Peter Honeyman, David A. Nowitz, and Brian E. Redman around 1983. 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 version from scratch in 1991. Taylor UUCP
14577-515: Was a new generation of binary transport. In practice, MIME has seen increased adoption in text messages, but it is avoided for most binary attachments. Some operating systems with metadata attached to files use specialized encoding formats. For Mac OS, both BinHex and special MIME types are used. Other lesser known encoding systems that may have been used at one time were BTOA , XX encoding , BOO , and USR encoding. In an attempt to reduce file transfer times, an informal file encoding known as yEnc
14706-400: Was a volunteer, largely successful effort to build a map of the connections between machines that were open mail relays 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
14835-464: Was associated with the Unix operating system developed at AT&T , but newsreaders were soon available for all major operating systems. Email client programs and Internet suites of the late 1990s and 2000s often included an integrated newsreader. Newsgroup enthusiasts often criticized these as inferior to standalone newsreaders that made correct use of Usenet protocols, standards and conventions. With
14964-573: Was conceived in 1979 and publicly established in 1980, at the University of North Carolina at Chapel Hill and Duke University , over a decade before the World Wide Web went online (and thus before the general public received access to the Internet ), making it one of the oldest computer network communications systems still in widespread use. It was originally built on the "poor man's ARPANET ", employing UUCP as its transport protocol to offer mail and file transfers, as well as announcements through
15093-579: Was contributed to UUCP Debian Linux package to adapt for the HERMES (High-Frequency Emergency and Rural Multimedia Exchange System) project, which provides UUCP HF connectivity. 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-like paths are still in use within
15222-441: Was error-corrected using a proprietary protocol based on MNP that ran over Telebit's half-duplex connections much better than g-protocol would normally, because in the common 64x3 case the remote system would be sending a constant stream of ACK s that would overflow the low-speed return channel. Combined with the modem's naturally higher data rates, they greatly improved overall throughput and generally performed about seven times
15351-551: Was formally shut down in late 2000. 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 (prior to its shut-down it had refused requests from new users for several years). One surviving feature of UUCP
15480-462: Was influenced by a wide array of technological developments and historical milestones. Computer networks enhance how users communicate with each other by using various electronic methods like email, instant messaging, online chat, voice and video calls, and video conferencing. Networks also enable the sharing of computing resources. For example, a user can print a document on a shared printer or use shared storage devices. Additionally, networks allow for
15609-429: Was introduced in 2001. It achieves about a 30% reduction in data transferred by assuming that most 8-bit characters can safely be transferred across the network without first encoding into the 7-bit ASCII space. The most common method of uploading large binary posts to Usenet is to convert the files into RAR archives and create Parchive files for them. Parity files are used to recreate missing data when not every part of
15738-669: Was originally written at AT&T Bell Laboratories by Mike Lesk . 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 . The first UUCP emails from the U.S. arrived in the United Kingdom in 1979 and email between the UK, the Netherlands and Denmark started in 1980, becoming a regular service via EUnet in 1982. The original UUCP
15867-799: Was released under the GNU General Public License . Taylor UUCP addressed security holes which allowed some of the original network worms 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 DOS systems. Packages such as UUSLAVE/GNUUCP ( John Gilmore , Garry Paxinos, Tim Pozar), UUPC/extended (Drew Derbyshire of Kendra Electronic Wonderworks) and FSUUCP (Christopher Ambler of IODesign), brought early Internet connectivity to personal computers, expanding
15996-582: Was revisited in the early 2000s. Similar techniques as those used by UUCP can apply to other networks that experience delay or significant disruption. Computer network A computer network is a set of computers sharing resources located on or provided by network nodes . Computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies based on physically wired, optical , and wireless radio-frequency methods that may be arranged in
16125-407: 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
16254-404: Was the dominant implementation. The e-protocol differs from the t-protocol only in that commands are not packetized and are instead sent as normal strings, while files are padded to the nearest 20 bytes. The uucp and uuxqt capabilities could be used to send email between machines, with suitable mail user interfaces and delivery agent programs. A simple UUCP mail address was formed from
16383-450: Was the first formal specification of the messages exchanged by Usenet servers. It was superseded by RFC 1036 and subsequently by RFC 5536 and RFC 5537. In cases where unsuitable content has been posted, Usenet has support for automated removal of a posting from the whole network by creating a cancel message, although due to a lack of authentication and resultant abuse, this capability is frequently disabled. Copyright holders may still request
16512-467: Was the only other implementation of Taylor's enhanced 'i' protocol, a significant improvement over the standard 'g' protocol used by most UUCP implementations. Before the widespread availability of Internet access , computers were only connected by smaller local area 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 telephone lines . UUCP used
16641-422: 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
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