Telenet

Telenet was a packet switched network which went into service in 1974. It was the first publicly available commercial packet-switched network service.

The original founding company, Telenet Inc., was established by Larry Roberts (former head of the ARPANet), and Barry Wessler. GTE acquired Telenet in 1979. It was later acquired by Sprint and called "Sprintnet". Sprint migrated customers from Telenet to the modern-day SprintLink IP network, one of many networks composing today's Internet. Telenet had its first offices in downtown Washington DC, then moved to McLean, Virginia. It was acquired by GTE while in McLean, and then moved offices in Reston, Virginia.

Under the various names, the company operated a public network, and also sold its packet switching equipment to other carriers and to large enterprise networks.

Coverage

Originally, the public network had switching nodes in seven US cities:

* Washington, D.C. (network operations center as well as switching)
* Boston, MA
* New York, NY
* Chicago, IL
* Dallas, TX
* San Francisco, CA
* Los Angeles, CA

The switching nodes were fed by Telenet Access Controller (TAC) terminal concentrators both colocated and remote from the switches. By 1980, there were over 1000 switches in the public network. At that time, the next largest network using Telenet switches was that of Southern Bell, which had approximately 250 switches.

Internal Network Technology

The initial network used statically-defined hop-by-hop routing, using Prime commercial minicomputers as switches, but then migrated to a purpose-built multiprocessing switch based on 6502 microprocessors. Among the innovations of this second-generation switch was a patented arbitrated bus interface that created a switching fabric, a shared bus in modern terms, among the microprocessors.

Most interswitch lines ran at 56 kbit/s, with a few, such as New York-Washington, at T1 (i.e., 1.544 Mbit/s). The main internal protocol was a proprietary variant on X.75; Telenet also ran standard X.75 gateways to other packet switching networks.

Originally, the switching tables could not be altered separately from the main executable code, and topology updates had to be made by deliberately crashing the switch code and forcing a reboot from the network management center. Improvements in the software allowed new tables to be loaded, but the network never used dynamic routing protocols. Multiple static routes, on a switch-by-switch basis, could be defined for fault tolerance. Network management functions continued to run on Prime minicomputers.

Its X.25 host interface was the first in the industry and Telenet helped standardize X.25 in the CCITT.

Telnet - protocol details

Telnet is a client-server protocol, based on a reliable connection-oriented transport. Typically this protocol used to establish a connection to TCP port 23, where a getty-equivalent program (telnetd) is listening, although Telnet predates TCP/IP and was originally run on NCP.

Initially, Telnet was an ad-hoc protocol with no official definition. Essentially, it used an 8-bit channel to exchange 7-bit ASCII data. Any byte with the high bit set was a special Telnet character.

On March 5th, 1973, a meeting was held at UCLA where "New Telnet" was defined in two NIC documents: Telnet Protocol Specification, NIC #15372, and Telnet Option Specifications, NIC #15373.

The protocol has many extensions, some of which have been adopted as Internet standards. IETF standards STD 27 through STD 32 define various extensions, most of which are extremely common. Other extensions are on the IETF standards track as proposed standards.

Telnet 5250

IBM 5250 or 3270 workstation emulation is supported via custom telnet clients, TN5250/TN3270, and IBM servers. Clients and servers designed to pass IBM 5250 data streams over Telnet generally do support SSL encryption, as SSH does not include 5250 emulation. Under OS/400, port 992 is the default port for secured telnet.

Telnet

Telnet (Telecommunication network) is a network protocol used on the Internet or local area network (LAN) connections. It was developed in 1969 beginning with RFC 15 and standardized as IETF STD 8, one of the first Internet standards.

The term telnet also refers to software which implements the client part of the protocol. Telnet clients are available for virtually all platforms. Most network equipment and OSes with a TCP/IP stack support some kind of Telnet service server for their remote configuration (including ones based on Windows NT). Because of security issues with Telnet, its use has waned as it is replaced by the use of SSH for remote access.

"To telnet" is also used as a verb meaning to establish or use a Telnet or other interactive TCP connection, as in, "To change your password, telnet to the server and run the passwd command".

Most often, a user will be telnetting to a Unix-like server system or a simple network device such as a router. For example, a user might "telnet in from home to check his mail at school". In doing so, he would be using a telnet client to connect from his computer to one of his servers. Once the connection is established, he would then log in with his account information and execute operating system commands remotely on that computer, such as ls or cd.

On many systems, the client may also be used to make interactive raw-TCP sessions. It is commonly believed that a telnet session which does not include an IAC (character 255) is functionally identical. This is not the case however due to special NVT (Network Virtual Terminal) rules such as the requirement for a bare CR (ASCII 13) to be followed by a NULL (ASCII 0).

Copyright issues

File sharing has grown in popularity with the proliferation of high-speed Internet connections, and the relatively small file size and high-quality MP3 audio format. File sharing is a legal technology with legal uses, however many users use it to give and accept copyrighted materials without permission or authorization, and this is viewed by some as piracy of intellectual property, also known as copyright infringement.

Despite the existence of various international treaties, there are still sufficient variations between countries to cause significant difficulties in the protection of copyright. Recent years have seen copyright owners challenging file sharing networks, leading to litigation by industry bodies against private individual file sharers. The legal issues surrounding file sharing have been the subject of debate and conferences, especially among lawyers in the entertainment industries.

The challenges facing copyright holders in the face of file sharing systems highlight that current copyright law and enforcement may not be sufficient in dealing with rapidly developing new technologies and uses. Other challenges include ambiguities in the interpretation of copyright law and varying copyright legislations. The high number of individuals engaged in file sharing of copyrighted material means that copyright holders face problems relating to mass litigation and the development of processes for evidence and discovery.

File sharing technology has evolved in response to legal challenges. There is a low technical barriers to entry for would-be sharers, and many file sharing approaches now obfuscate or hide the fact that sharing is happening, or the identities of those involved. For example: encryption and darknets. Furthermore it is contested whether the transfer of segmented files constitutes copyright infringement in itself based on existing laws.

Further challenges have arisen because of the need to balance self-protection against fair use. A perceived overbalance towards protection (in the form of media that cannot be backed up, cannot be played on multiple systems by the owner, or contains rootkits or irksome security systems inserted by manufacturers), has led to a backlash against protection systems in some quarters. For example, the first crack of AACS was inspired by a perceived unfair restriction on owner usage.