xinetd控制一些系统服务的运行

    xinetd 的默认配置文件  :  /etc/xinetd.conf

[root@localhost ~]# cat /etc/xinetd.conf | grep -E "^[^#]"
defaults
{
	log_type	= SYSLOG daemon info 
	log_on_failure	= HOST
	log_on_success	= PID HOST DURATION EXIT
	cps		= 50 10
	instances	= 50      #  xinetd  最多唤醒的进程数
	per_source	= 10     #  同一个服务在同一个服务端最多能连接的个数
	v6only		= no
	groups		= yes
	umask		= 002
}
includedir /etc/xinetd.d

        如果单个服务的配置文件中没配置这些参数 ，则使用xinetd默认的配置

当访问xinetd控制的进程时，xinetd拦截来访者，确认是符符合设置的条件 ，如果符合则唤醒相对应服务 的进程 ，否则禁止访问

当开启  xinetd  后  chkconfig 查看 

[root@localhost ~]# chkconfig xinetd on
[root@localhost ~]# chkconfig
NetworkManager 	0:off	1:off	2:on	3:on	4:on	5:on	6:off
abrtd          	0:off	1:off	2:off	3:on	4:off	5:on	6:off
………………
vsftpd         	0:off	1:off	2:off	3:on	4:on	5:on	6:off
wpa_supplicant 	0:off	1:off	2:off	3:off	4:off	5:off	6:off
xinetd         	0:off	1:off	2:on	3:on	4:on	5:on	6:off

xinetd based services:
	chargen-dgram: 	off
	chargen-stream:	off
	daytime-dgram: 	off
	daytime-stream:	off
	discard-dgram: 	off
	discard-stream:	off
	echo-dgram:    	off
	echo-stream:   	off
	rsync:         	off
	tcpmux-server: 	off
	telnet:        	on
	tftp:          	on
	time-dgram:    	off
	time-stream:   	off
[root@localhost ~]# 

    下面多了一列被  xinetd  控制的服务

开启单个服务 

[root@localhost ~]# chkconfig tftp on

[root@localhost xinetd.d]# vim telnet 

# default: on
# description: The telnet server serves telnet sessions; it uses 
#       unencrypted username/password pairs for authentication.
service telnet
{
        disable = no
        flags           = REUSE
        socket_type     = stream
        wait            = no    
        user            = root    #  以root身份运行
        server          = /usr/sbin/in.telnetd     #这个服务的主进程 在 log_on_failure  += USERID
        server_args  =  -S #  这个进程带的参数 
        instances        4   #
        per_source       1   #一个ip只允许连接一个
        only_from = 192.168.0.0/24   #  允许
        no_access = 192.168.0.1     #  拒绝
 }
~ 

        server_args   -S #  这个进程带的参数