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Daytime Protocol
The Daytime Protocol is a service in the Internet Protocol Suite, defined in 1983 in by Jon Postel. It is intended for testing and measurement purposes in computer networks. A host may connect to a server that supports the Daytime Protocol on either Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) port 13. The server returns an ASCII character string of the current date and time in an unspecified format. Inetd implementation On UNIX-like operating systems a daytime server is usually built into the inetd (or xinetd) daemon. The service is usually not enabled by default. It may be enabled by adding the following lines to the file and telling inetd to reload its configuration: daytime stream tcp nowait root internal daytime dgram udp wait root internal An example output may be: Thursday, February 2, 2006, 13:45:51-PST See also * List of well-known ports * Echo Protocol * QOTD * Time Protocol * Network Time Protocol The Net ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet Protocol Suite
The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP). Early versions of this networking model were known as the Department of Defense (DoD) model because the research and development were funded by the United States Department of Defense through DARPA. The Internet protocol suite provides end-to-end data communication specifying how data should be packetized, addressed, transmitted, routed, and received. This functionality is organized into four abstraction layers, which classify all related protocols according to each protocol's scope of networking. An implementation of the layers for a particular application forms a protocol stack. From lowest to highest, the layers are the l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jon Postel
Jonathan Bruce Postel (; August 6, 1943 – October 16, 1998) was an American computer scientist who made many significant contributions to the development of the Internet, particularly with respect to Internet Standard, standards. He is known principally for being the Editor of the Request for Comments, Request for Comment (RFC) document series, for Simple Mail Transfer Protocol (SMTP), and for administering the Internet Assigned Numbers Authority (IANA) until his death. During his lifetime he was referred to as the "god of the Internet" for his comprehensive influence; Postel himself noted that this "compliment" came with a barb, the suggestion that he should be replaced by a "professional," and responded with typical self-effacing matter-of-factness: "Of course, there isn’t any 'God of the Internet.' The Internet works because a lot of people cooperate to do things together." Career Postel attended Van Nuys High School, and then UCLA where he earned his B.S. (1966) as well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmission Control Protocol
The Transmission Control Protocol (TCP) is one of the main communications protocol, 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 reliability (computer networking), reliable, ordered, and error detection and correction, error-checked delivery of a reliable byte stream, stream of octet (computing), octets (bytes) between applications running on hosts communicating via an IP network. Major internet applications such as the World Wide Web, email, remote administration, and file transfer rely on TCP, which is part of the transport layer of the TCP/IP suite. Transport Layer Security, SSL/TLS often runs on top of TCP. TCP is Connection-oriented communication, connection-oriented, meaning that sender and receiver firstly need to establish a connection based on agreed parameters; they do this through three-way Ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
User Datagram Protocol
In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in Network packet, packets) to other hosts on an Internet Protocol (IP) network. Within an IP network, UDP does not require prior communication to set up communication channels or data paths. UDP is a connectionless protocol, meaning that messages are sent without negotiating a connection and that UDP does not keep track of what it has sent. UDP provides checksums for data integrity, and port numbers for addressing different functions at the source and destination of the datagram. It has no Handshake (computing), handshaking dialogues and thus exposes the user's program to any Reliability (computer networking), unreliability of the underlying network; there is no guarantee of delivery, ordering, or duplicate protection. If error-correction facilities are needed at the network interface level, an applica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNIX-like
A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-like Application software, application is one that behaves like the corresponding List of POSIX commands, Unix command or Unix shell, shell. Although there are general Unix philosophy, philosophies for Unix design, there is no technical standard defining the term, and opinions can differ about the degree to which a particular operating system or application is Unix-like. Some well-known examples of Unix-like operating systems include Linux, FreeBSD and OpenBSD. These systems are often used on servers as well as on personal computers and other devices. Many popular applications, such as the Apache HTTP Server, Apache web server and the Bash (Unix shell), Bash shell, are also designed to be used on Unix-like systems. Definition The Open ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inetd
inetd (internet service daemon) is a super-server Daemon (computer software), daemon on many Unix systems that provides Internet services. For each configured service, it listens for requests from connecting clients. Requests are served by spawning a process which runs the appropriate executable, but simple services such as ''echo'' are served by inetd itself. External executables, which are run on request, can be single- or multi-threaded. First appearing in BSD, 4.3BSD, it is generally located at /usr/sbin/inetd. inetd is based on the (service) activator pattern Function Often called a super-server, inetd listens on designated TCP and UDP port, ports used by Internet services such as File Transfer Protocol, FTP, POP3, and telnet. When a Transmission Control Protocol, TCP packet or User Datagram Protocol, UDP packet arrives with a particular destination port number, inetd launches the appropriate server program to handle the connection. For services that are not expected to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xinetd
In computer networking, xinetd (''Extended Internet Service Daemon'') is an open-source software, open-source super-server Daemon (computer software), daemon which runs on many Unix-like operating system, systems, and manages Internet-based connectivity. It offers a more secure alternative to the older inetd ("the Internet daemon"), which most modern Linux distributions have deprecated. Description xinetd listens for incoming requests over a network and launches the appropriate Network service, service for that request. Requests are made using port numbers as identifiers and xinetd usually launches another Daemon (computing), daemon to handle the request. It can be used to start services with both privileged and non-privileged port numbers. xinetd features access control mechanisms such as TCP Wrapper Access control list, ACLs, extensive data logging, logging capabilities, and the ability to make Service (systems architecture), services available based on time. It can place ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daemon (computer Software)
In computing, a daemon is a program that runs as a background process, rather than being under the direct control of an interactive user. Customary convention is to name a daemon process with the letter ''d'' as a suffix to indicate that it's a daemon. For example, is a daemon that implements system logging facility, and is a daemon that serves incoming SSH connections. Even though the concept can apply to many computing systems, the term ''daemon'' is used almost exclusively in the context of Unix-based systems. In other contexts, different terms are used for the same concept. Systems often start daemons at boot time that will respond to network requests, hardware activity, or other programs by performing some task. Daemons such as cron may also perform defined tasks at scheduled times. Terminology In the context of computing, the word is generally pronounced either as or . The term was coined by the programmers at MIT's Project MAC. According to Fernando J. Corbat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Well-known Ports (computing)
This is a list of TCP and UDP port numbers used by protocols for operation of network applications. The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) only need one port for bidirectional traffic. TCP usually uses port numbers that match the services of the corresponding UDP implementations, if they exist, and vice versa. The Internet Assigned Numbers Authority (IANA) is responsible for maintaining the official assignments of port numbers for specific uses, However, many unofficial uses of both well-known and registered port numbers occur in practice. Similarly, many of the official assignments refer to protocols that were never or are no longer in common use. This article lists port numbers and their associated protocols that have experienced significant uptake. Table legend Well-known ports The port numbers in the range from 0 to 1023 (0 to 210 − 1) are the ''well-known ports'' or ''system ports''. They are used by system processes that provide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QOTD
The Quote of the Day (QOTD) service is a member of the Internet protocol suite, defined in 1983 in RFC 865 by Jon Postel. As indicated there, the QOTD concept predated the specification, when QOTD was used by mainframe sysadmins to broadcast a daily quote on request by a user. It was then formally codified both for prior purposes as well as for testing and measurement purposes. A host may connect to a server that supports the QOTD protocol, on either TCP or UDP port 17. To keep the quotes at a reasonable length, RFC 865 specifies a maximum of 512 octets for the quote. Although some sources indicate that the QOTD service is rarely enabled, and is in any case often firewalled to avoid denial-of-service attacks, interest continues in the pre-existing purpose of serving quotes as can be seen with web engine searches. Current testing and measurement of IP network The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time Protocol
The Time Protocol is a network protocol in the Internet Protocol Suite. Its purpose is to provide a site-independent, machine readable date and time. The Time Protocol may be implemented over the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP). A host connects to a server that supports the Time Protocol on port 37. The server then sends the time as a 32-bit unsigned integer in binary format and in network byte order, representing the number of seconds since 00:00 (midnight) 1 January 1900 GMT, and closes the connection. Operation over UDP requires the sending of any datagram to the server port, as there is no connection setup for UDP. The fixed 32-bit data format means that the timestamp rolls over approximately every 136 years, with the first such occurrence on . Programs that use the Time Protocol must be carefully designed to use context-dependent information to distinguish these dates from those in 1900. Many Unix-like operating systems used the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
