Networking Terminology

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Last Updated: 04.03.2017

(Most of this information is sourced from Wikipedia.org).

A list of terms you may encounter while dealing with networking and internet access. Should help a little while reading the other documents relating to internet access from QDOS and SMSQ/E.

BSD = Berkeley Software Distribution

A Unix operating system derivative developed and distributed by the Computer Systems Research Group (CSRG) of the University of California, Berkeley, from 1977 to 1995. Today the term "BSD" is often used non-specifically to refer to any of the BSD descendants which together form a branch of the family of Unix-like operating systems. Operating systems derived from the original BSD code remain actively developed and widely used.

CLIENT

A client is a piece of computer hardware or software that accesses a service made available by a server. The server is often (but not always) on another computer system, in which case the client accesses the service by way of a network. The term applies to the role that programs or devices play in the client-server model.

DATAGRAM

Logical grouping of information sent as a network layer unit over a transmission medium without prior establishment of a virtual circuit. IP datagrams are the primary information units in the Internet. The terms frame, message, packet, and segment are also used to describe logical information grouping at various layers of the OSI reference model and in various technology circles.

FTP = File Transfer Protocol

The File Transfer Protocol (FTP) is a standard network protocol used for the transfer of computer files from a server to a client using the Client-server model on a computer network. FTP is built on a client-server model architecture and uses separate control and data connections between the client and the server. FTP users may authenticate themselves with a clear-text sign-in protocol, normally in the form of a username and password, but can connect anonymously if the server is configured to allow it. For secure transmission that protects the username and password, and encrypts the content, FTP is often secured with SSL/TLS (FTPS). SSH File Transfer Protocol (SFTP) is sometimes also used instead, but is technologically different. The first FTP client applications were command-line programs developed before operating systems had graphical user interfaces, and are still shipped with most Windows, Unix, and Linux operating systems. Many FTP clients and automation utilities have since been developed for desktops, servers, mobile devices, and hardware, and FTP has been incorporated into productivity applications, such as web page editors.

SFTP = SSH File Transfer Protocol

SFTP, which stands for SSH File Transfer Protocol, or Secure File Transfer Protocol, is a separate protocol packaged with SSH that works in a similar way over a secure connection. The advantage is the ability to leverage a secure connection to transfer files and traverse the filesystem on both the local and remote system. In almost all cases, SFTP is preferable to FTP because of its underlying security features and ability to piggy-back on an SSH connection. FTP is an insecure protocol that should only be used in limited cases or on networks you trust.

GOPHER

A Gopher server presents its contents as a hierarchically structured list of files. With the ascendance of the Web, many gopher databases were converted to Web sites which can be more easily accessed via Web search engines. Gopher was developed at the University of Minnesota and named after the school's mascot. The Gopher protocol is a TCP/IP application layer protocol designed for distributing, searching, and retrieving documents over the Internet. The Gopher protocol was strongly oriented towards a menu-document design and presented an alternative to the World Wide Web in its early stages, but ultimately HTTP became the dominant protocol. The Gopher ecosystem is often regarded as the effective predecessor of the World Wide Web.

HOST

A network host is a computer or other device connected to a computer network. A network host may offer information resources, services, and applications to users or other nodes on the network. A network host is a network node that is assigned a network layer host address.

HTML = HyperText Markup Language

Hypertext is text files allowing direct access to other texts by way of encoded links. Hypertext documents can be created using HTML, which is a formatting language that uses tags within the text to indicate how a given part of a document should be interpreted by a viewing application such as a browser. Hypertext files often integrate images, sound, and other media.

HTTP = HyperText Transfer Protocol

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, and hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web. Hypertext is structured text that uses logical links (hyperlinks) between nodes containing text.

IANA = Internet Assigned Numbers Authority

IANA delegates authority for IP address-space allocation and domain-name assignment to the NIC (Network InformationCenter) and other organizations. IANA also maintains a database of assigned protocol identifiers used in the TCP/IP stack, including autonomous system numbers.

IMAP = Internet Message Access Protocol

A standard email protocol that stores email messages on a mail server, but allows the end user to view and manipulate the messages as though they were stored locally on the end user's computing device(s).

IP = Internet Protocol

The Internet Protocol (IP) is the principal communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP has the task of delivering packets from the source host to the destination host solely based on the IP addresses in the packet headers. For this purpose, IP defines packet structures that encapsulate the data to be delivered. It also defines addressing methods that are used to label the datagram with source and destination information. The first major version of IP, Internet Protocol Version 4 (IPv4), is the dominant protocol of the Internet. Its successor is Internet Protocol Version 6 (IPv6).

IP ADDRESS

32 bit address assigned to hosts using TCP/IP.  An IP address belongs to one of five classes (A, B, C, D, or E) and is written as 4 octets separated with periods (dotted decimal format). Each address consists of a network number, an optional subnet work number, and a host number. The network and subnetwork numbers together are used for routing, while the host number is used to address an individual host within the network or subnetwork. A subnet mask is used to extract network and subnetwork information from the IP address. Also called an Internet address.

LAN = Local Area Network

A communication infrastructure that supports data and resource sharing within a small area (<2 km diameter) that is completely contained on the premises of a single owner.

LATENCY

The delay in transmission time that occurs while information remains in a device's buffered memory (such as a bridge or router) before it can be sent along its path.

LAYER

A term used to describe a group of communication functions and the protocols implemented to perform them as defined by a network standards organization, most often referring to a group of functions as described by the OSI 7-Layer Model designated by the ISO.

NETDB = Network Database

NetDB is a database tool used primarily by LNAs (local network administrators) and IT Services staff to assign and manage IP addresses for computers and printers.

NFS = Network File System.

A file metalanguage and set of procedure calls to access and manage files that is standard issue on nearlyevery computer that uses TCP/IP protocols as its standard network protocols. Designed by Sun Microsystems, NFS is now a standard feature of nearly all Unix systems.

OCTET

A group of 8 bits, or a Byte.

PEER

A device to which a computer has a network connection that is relatively symmetrical, i.e. where both devices can initiate or respond to a similar set of requests.

POP3 = Post Office Protocol 3

The most recent version of a standard protocol for receiving e-mail. POP3 is a client/server protocol in which e-mail is received and held for you by your Internet server.

PORT

In the internet protocol suite, a port is an endpoint of communication in an operating system. In software it is a logical construct that identifies a specific process or a type of network service. A port is always associated with an IP address of a host and the protocol type of the communication, and thus completes the destination or origination network address of a communication session. A port is identified for each address and protocol by a 16-bit number, commonly known as the port number. For example, an address may be "protocol: TCP, IP address: 1.2.3.4, port number: 80", which may be written 1.2.3.4:80 when the protocol is known from context.

PROTOCOL

A specification of the data structures and algorithms necessary to accomplish a particular network function.

SERVER

In computing, a server is a computer program or a device that provides functionality for other programs or devices, called "clients". This architecture is called the client-server model, and a single overall computation is distributed across multiple processes or devices.

SMTP = Simple Mail Transfer Protocol.

Standard protocol for transferring email over TCP/IP networks. First defined by RFC 821 in 1982, it was last updated in 2008 with Extended SMTP additions by RFC 5321, which is the protocol in widespread use today.

SOCKET

A network socket is an internal endpoint for sending or receiving data at a single node in a computer network. Concretely, it is a representation of this endpoint in the networking software (protocol stack), such as an entry in a table (listing communication protocol, destination, status, etc.), and is a form of system resource. The term "socket" is by analogy with physical female connectors, communication between two nodes through a channel being visualized as a cable with two male connectors plugging into sockets at each node. Similarly, the term "port" (another term for a female connector) is used for external endpoints at a node, and the term "socket" is also used for an internal endpoint of local inter-process communication (IPC) (not over a network). However, the analogy is strained, as network communication need not be one-to-one or have a channel.

TCP = Transmission Control Protocol

The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore. the entire suite is commonly referred to as TCP/IP. TCP provides reliable, ordered and error-checked delivery of a stream of octets (8-bit bytes) between applications running on hosts communicating by an IP network. Major internet applications such as the World Wide Web, email, remote administration, and file transfer rely on TCP. Applications that do not require reliable data stream service may use the User Datagram Protocol (UDP), which provides a connectionless datagram service that emphasises reduced latency over reliability.

TELNET

A process to access a remote computer system, often a Unix system, over the network. Telnet is a protocol used on the Internet or local area networks to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. User data is interspersed in-band with Telnet control information in an 8-bit byte oriented data connection over the Transmission Control Protocol (TCP). The name originates from the term Teletype Network.

UDP = User Datagram Protocol

The User Datagram Protocol (UDP) is a transport layer protocol defined for use with the IP network layer protocol. It is defined by RFC 768 written by John Postel. It provides a best-effort datagram service to an End System (IP host). The service provided by UDP is an unguaranteed service that provides no guarantee for delivery and no protection from duplication e.g. if this arises due to software errors within an intermediate system. UDP does not provide any communications security. It's an alternative communications protocol to TCP used primarily for establishing low-latency and loss tolerating connections between applications on the internet. Both protocols send short packets of data called Datagrams.

URI = Uniform Resource Identifier

In information technology, a Uniform Resource Identifier (URI) is a string of characters used to identify a resource. Such identification enables interaction with representations of the resource over a network, typically the World Wide Web, using specific protocols. Schemes specifying a concrete syntax and associated protocols define each URI. The most common form of URI is the Uniform Resource Locator (URL), frequently referred to informally as a web address. More rarely seen in usage is the Uniform Resource Name (URN), which was designed to complement URLs by providing a mechanism for the identification of resources in particular namespaces.

URL = Uniform Resource Locator

A reference to a web resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is a specific type of Uniform Resource Identifier (URI), although many people use the two terms interchangeably. A URL implies the means to access an indicated resource, which is not true of every URI. URLs occur most commonly to reference web pages (http), but are also used for file transfer, email, database access, and many other applications. A typical URL could have the form http://www.example.com/index.html, which indicates a protocol (http), a hostname (www.example.com) and a file name (index.html).

PORT NUMBERS

In the internet protocol suite, a port is an endpoint of communication in an operating system. In software it is a logical construct that identifies a specific process or a type of network service. A port is always associated with an IP address of a host and the protocol type of the communication, and thus completes the destination or origination network address of a communication session. A port is identified for each address and protocol by a 16-bit number, commonly known as the port number. For example, an address may be "protocol: TCP, IP address: 1.2.3.4, port number: 80", which may be written 1.2.3.4:80 when the protocol is known from context. Specific port numbers are often used to identify specific services. Of the thousands of enumerated ports, 1024 well-known port numbers are reserved by convention to identify specific service types on a host. In the client-server model of application architecture, the ports that network clients connect to for service initiation provide a multiplexing service. After initial communication binds to the well-known port number, this port is freed by switching each instance of service requests to a dedicated, connection-specific port number, so that additional clients can be serviced. The protocols that primarily use ports are the transport layer protocols, such as the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP). Ports were unnecessary on direct point-to-point links when the computers at each end could only run one program at a time. Ports became necessary after computers became capable of executing more than one program at a time and were connected to modern packet-switched networks.  A port number is a 16-bit unsigned integer, thus ranging from 0 to 65535.

Here are some commonly reserved port numbers:

21: File Transfer Protocol (FTP)
22: Secure Shell (SSH)
23: Telnet remote login service
25: Simple Mail Transfer Protocol (SMTP)
53: Domain Name System (DNS) service
80: Hypertext Transfer Protocol (HTTP) used in the World Wide Web
110: Post Office Protocol (POP3)
119: Network News Transfer Protocol (NNTP)
123: Network Time Protocol (NTP)
143: Internet Message Access Protocol (IMAP)
161: Simple Network Management Protocol (SNMP)
194: Internet Relay Chat (IRC)
443: HTTP Secure (HTTPS)

For TCP port 0 is reserved and cannot be used. For UDP, the source port is optional and a value of 0 means no port.

The registered ports are those from 1024 through 49151. IANA maintains the official list of well-known and registered ranges. The dynamic or private ports are those from 49152 through 65535.

The full list of port numbers is available from IANA (Internet Assigned Numbers Authority), at
https://www.iana.org/assignments/service-names-port-numbers/service-names-port- numbers.xhtml

SOURCES OF INFORMATION

One source of information on all things internet is the RFC (Request For Comment) documents. They are not standards definitions as such, but are still full of information. For example, RFC1945 discusses the HTTP (HyperText Transfer Protocol) 1.0 standard.
http://www.ietf.org/rfc/rfc-index.txt

Some potentially useful ones to read:

RFC

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