UNIX's daemon (server) basically has two categories: The server running is automatically started from the / etc / rc when the operating system is started. Servers initiated by boot time typically provide quick services to users, must handle many network requests from a single server process or both. Such servers typically have sendmail, httpd, etc. Servers that only run when needed to start from inetd (xinetd) Unix Internet Daemon. The inetd super server monitors multiple TCP / IP ports waiting for the entry request, and can automatically start the daemon's flexible program. . When a request is received, it will derive a corresponding server. By using super servers, other services can only be derived when needed, saving system resources. When the connection ends, the derived server will stop running. The name of many TCP / IP daemon is after the name of the service it provides, after the letter "D" composition, such as Wu-ftpd, this command mode is to indicate that the command is a daemon. The LPD line printer daemon is also called the print buffer handler, executed when the system is booted. Laborful in a specific TCP / IP port and queues these print tasks locally or remote systems. RARPD RARP daemon This daemon can respond to the Reverse Address Resolution Protocol (RARP) request, other clients typically use RARP to find 32-bit IP addresses based on a given 48-bit Ethernet address when booting. Guide the machine to send its Ethernet information with RARP request packets. For this request, the server running RARPD must respond to it. The BootPD Bootp Remote Start Trigger Removal The Internet Boot Protocol server, which automatically launches this daemon by the inetd super server when the boot request is reached. If Bootpd does not receive his boot request after 15 minutes of receiving the last request, it will automatically exit to save system resources. The target of the Internet Boot Protocol server is to provide network information for clients, including client IP addresses, network masking, broadcast addresses, DNS servers and router addresses. The routed routing information daemon is mainly to manage the Internet routing table. When using the static route, it is not necessary to start the routed. Note: Do not start the routed, starting the routed is not necessarily a router, the route must be IP forwading support in the kernel; if the kernel has IP forwarding support, ROUTED can also be router, but the dynamic update of routing tables cannot be implemented. *** Gated is a function than ROUTED routing information management process. The Named DNS daemon provides DNS service. Syslogd System Record Guarding This process is responsible for recording a variety of system information in a series of files described in profile /etc/syslog.conf. Each message is saved as a row in the file and can contain various information. Syslogd receives the message sent to you and is stored in its log file. Information includes notification, error, status, and tunability messages. Every message is related to its related importance level. INETD Super Server INETD Super Server monitors multiple TCP / IP ports waiting for entry. When a request is received, it will derive a corresponding server. By using a super server, other services can be sent only when needed, saving system resources. When the connection is terminated, the derived server will stop running. Usually inetd started servers by fingerd, ftpd, rexecd, rlogind, telnetd, etc.
