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Superserver 2
A super-server or sometimes called a service dispatcher is a type of daemon run generally on Unix-like systems. Usage A super-server starts other servers when needed, normally with access to them checked by a TCP wrapper. It uses very few resources when in idle state. This can be ideal for workstations used for local web development, client/server development or low-traffic daemons with occasional usage (such as ident and SSH). Performance The creation of an operating system process embodying the sub-daemon is deferred until an incoming connection for the sub-daemon arrives. This results in a delay to the handling of the connection (in comparison to a connection handled by an already-running process). Whether this delay is incurred repeatedly for every incoming connection depends on the design of the particular sub-daemon; simple daemons usually require a separate sub-daemon instance (i.e. a distinct, separate operating system process) be started for each and every incoming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super-server
A super-server or sometimes called a service dispatcher is a type of daemon run generally on Unix-like systems. Usage A super-server starts other servers when needed, normally with access to them checked by a TCP wrapper. It uses very few resources when in idle state. This can be ideal for workstations used for local web development, client/server development or low-traffic daemons with occasional usage (such as ident and SSH). Performance The creation of an operating system process embodying the sub-daemon is deferred until an incoming connection for the sub-daemon arrives. This results in a delay to the handling of the connection (in comparison to a connection handled by an already-running process). Whether this delay is incurred repeatedly for every incoming connection depends on the design of the particular sub-daemon; simple daemons usually require a separate sub-daemon instance (i.e. a distinct, separate operating system process) be started for each and every incomin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superserver 2
A super-server or sometimes called a service dispatcher is a type of daemon run generally on Unix-like systems. Usage A super-server starts other servers when needed, normally with access to them checked by a TCP wrapper. It uses very few resources when in idle state. This can be ideal for workstations used for local web development, client/server development or low-traffic daemons with occasional usage (such as ident and SSH). Performance The creation of an operating system process embodying the sub-daemon is deferred until an incoming connection for the sub-daemon arrives. This results in a delay to the handling of the connection (in comparison to a connection handled by an already-running process). Whether this delay is incurred repeatedly for every incoming connection depends on the design of the particular sub-daemon; simple daemons usually require a separate sub-daemon instance (i.e. a distinct, separate operating system process) be started for each and every incoming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daemon (computer Software)
In multitasking computer operating systems, a daemon ( or ) is a computer program that runs as a background process, rather than being under the direct control of an interactive user. Traditionally, the process names of a daemon end with the letter ''d'', for clarification that the process is in fact a daemon, and for differentiation between a daemon and a normal computer program. For example, is a daemon that implements system logging facility, and is a daemon that serves incoming SSH connections. In a Unix environment, the parent process of a daemon is often, but not always, the init process. A daemon is usually created either by a process forking a child process and then immediately exiting, thus causing init to adopt the child process, or by the init process directly launching the daemon. In addition, a daemon launched by forking and exiting typically must perform other operations, such as dissociating the process from any controlling terminal (tty). Such procedures are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix-like
A Unix-like (sometimes referred to as UN*X 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 is one that behaves like the corresponding Unix command or shell. Although there are general 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 and BSD. These systems are often used on servers, as well as on personal computers and other devices. Many popular applications, such as the Apache web server and the Bash shell, are also designed to be used on Unix-like systems. One of the key features of Unix-like systems is their ability to support multiple users and processes simultaneously. This allows users to run multipl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Server (computing)
In computing, a server is a piece of computer hardware or software (computer program) that provides functionality for other programs or devices, called " clients". This architecture is called the client–server model. Servers can provide various functionalities, often called "services", such as sharing data or resources among multiple clients, or performing computation for a client. A single server can serve multiple clients, and a single client can use multiple servers. A client process may run on the same device or may connect over a network to a server on a different device. Typical servers are database servers, file servers, mail servers, print servers, web servers, game servers, and application servers. Client–server systems are usually most frequently implemented by (and often identified with) the request–response model: a client sends a request to the server, which performs some action and sends a response back to the client, typically with a result or acknowledg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TCP Wrapper
__NOTOC__ TCP Wrappers (also known as tcp_wrappers) is a host-based networking ACL system, used to filter network access to Internet Protocol servers on (Unix-like) operating systems such as Linux or BSD. It allows host or subnetwork IP addresses, names and/or ident query replies, to be used as tokens on which to filter for access control purposes. The original code was written by Wietse Venema in 1990 to monitor a cracker's activities on the Unix workstations at the Department of Math and Computer Science at the Eindhoven University of Technology. He maintained it until 1995, and on June 1, 2001, released it under its own BSD-style license. The tarball includes a library named libwrap that implements the actual functionality. Initially, only services that were spawned for each connection from a super-server (such as inetd) got ''wrapped'', utilizing the tcpd program. However most common network service daemons today can be linked against libwrap directly. This is used by dae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Workstations
A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating systems. The term ''workstation'' has been used loosely to refer to everything from a mainframe computer terminal to a PC connected to a network, but the most common form refers to the class of hardware offered by several current and defunct companies such as Sun Microsystems, Silicon Graphics, Apollo Computer, DEC, HP, NeXT, and IBM which powered the 3D computer graphics revolution of the late 1990s. Workstations offer higher performance than mainstream personal computers, especially in CPU, graphics, memory, and multitasking. Workstations are optimized for the visualization and manipulation of different types of complex data such as 3D mechanical design, engineering simulations like computational fluid dynamics, animation, medical imaging, image rendering, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Web Development
Web development is the work involved in developing a website for the Internet (World Wide Web) or an intranet (a private network). Web development can range from developing a simple single static page of plain text to complex web applications, electronic businesses, and social network services. A more comprehensive list of tasks to which Web development commonly refers, may include Web engineering, Web design, Web content development, client liaison, client-side/server-side scripting, Web server and network security configuration, and e-commerce development. Among Web professionals, "Web development" usually refers to the main non-design aspects of building Web sites: writing markup and coding. Web development may use content management systems (CMS) to make content changes easier and available with basic technical skills. For larger organizations and businesses, Web development teams can consist of hundreds of people (Web developers) and follow standard methods like Agil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ident Protocol
The Ident Protocol (Identification Protocol, Ident), specified iRFC 1413 is an Internet protocol that helps identify the user of a particular TCP connection. One popular daemon program for providing the ident service is identd. Function The Ident Protocol is designed to work as a server daemon, on a user's computer, where it receives requests to a specified TCP port, generally 113. In the query, a client specifies a pair of TCP ports (a local and a remote port), encoded as ASCII decimals and separated by a comma (,). The server then sends a response that identifies the username of the user who runs the program that uses the specified pair of TCP ports, or specifies an error. Suppose host A wants to know the name of the user who is connecting to its TCP port 23 (Telnet) from the client's (host B) port 6191. Host A would then open a connection to the ident service on host B, and issue the following query: 6191, 23 As TCP connections generally use one unique local port (6191 in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secure Shell
The Secure Shell Protocol (SSH) is a cryptographic network protocol for operating network services securely over an unsecured network. Its most notable applications are remote login and command-line execution. SSH applications are based on a client–server architecture, connecting an SSH client instance with an SSH server. SSH operates as a layered protocol suite comprising three principal hierarchical components: the ''transport layer'' provides server authentication, confidentiality, and integrity; the ''user authentication protocol'' validates the user to the server; and the ''connection protocol'' multiplexes the encrypted tunnel into multiple logical communication channels. SSH was designed on Unix-like operating systems, as a replacement for Telnet and for unsecured remote Unix shell protocols, such as the Berkeley Remote Shell (rsh) and the related rlogin and rexec protocols, which all use insecure, plaintext transmission of authentication tokens. SSH was first de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inetd
inetd (internet service daemon) is a super-server 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 4.3BSD, it is generally located at /usr/sbin/inetd. Function Often called a super-server, inetd listens on designated ports used by Internet services such as FTP, POP3, and telnet. When a TCP packet or 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 run with high loads, this method uses memory more efficiently, since the specific servers run only when needed. Furthermore, in inetd's "nowait" mode of service management, no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Launchd
launchd is an init and operating system service management daemon created by Apple Inc. as part of macOS to replace its BSD-style init and SystemStarter. There have been efforts to port launchd to FreeBSD and derived systems. Components There are two main programs in the launchd system: launchd and launchctl. ''launchd'' manages the daemons at both a system and user level. Similar to xinetd, launchd can start daemons on demand. Similar to watchdogd, launchd can monitor daemons to make sure that they keep running. launchd also has replaced init as PID 1 on macOS and as a result it is responsible for starting the system at boot time. Configuration files define the parameters of services run by launchd. Stored in the LaunchAgents and LaunchDaemons subdirectories of the Library folders, the property list-based files have approximately thirty different keys that can be set. launchd itself has no knowledge of these configuration files or any ability to read them - that is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
