Understanding Linux System Services

Select the start service www.2cto in the "setup" dialog box. comservice: A resident memory process. The service must have a corresponding daemon (daemon process). daemon is divided into two categories: stand_alone: always in the memory, fast response superdaemon: Use one... knowing that the Linux system service setup selects www.2cto.com service, which is a resident memory process, services must have corresponding daemon (daemon process). daemon has two categories: stand_alone: always in memory, fast response super daemon: use a special super daemon (implemented by the xinetd process) for management, wake up when the client requests, and close the service after the client requests are completed. Slow response: xinetd is used to manage other daemon instances. it is a stand_alone daemondaemon name. the corresponding service name is followed by the d-pilot Port: it is used to identify unused service requests (www for the same website address is different from the ftp access port, and the default www port is 80). the port number corresponds to/etc/services, and it is not recommended to modify some directories: /etc/init. d. where is the startup script placed, all servers? Miss ??? All scripts are stored in ?? ,/Etc/sysconfig/* various service initialization environment configuration files/etc/xinetd. conf,/etc/xinetd. d/* super daemon configuration file ----------------------------------------------------------------------------------------------------------------------- stand_alone service startup: (sometimes only sudo can be started) 1. /etc/init. d/* (start | stop | restart | ...) 2. start with service. The service is just a script. you can analyze the following parameter usage: service [service name] (start | stop | restart | ...) service -- status-all displays the startup of all stand alone services managed by super daemon: step1. modify the configuration file/etc/xinetd. d/*, set "disable = no" step2. after modifying the configuration, restart xinetd (sudo is required) to view which are started: grep-I 'disable'/etc/xinetd. d/* firewall configuration mainly uses two files:/etc/hosts. allow/etc/hosts. deny format: <服务（程序名）> : : <操作> Generally, the allowed IP address is placed in hosts. allow, which is rejected in hosts. deny example: vi/etc/hosts. allow rsync: 192.168.0.0/255.255.255.0: allow ====== "" can be omitted because it is in hosts. in allow, the default value is allow route www.2cto.com. view the services started by the system. View network services: netstat-tulp. View listening services: netstat-lnp. View all services: service -- status-all restart sets the service to start (use chkconfig) to check whether rsunc has started netstat-tlup | grep rsync to check whether the service is started by default: chkconfig -- list rsync to disable auto-start: chkconfig rsync off service xinetd restart (do not forget this step) can be selected in setup, then boot