1XINETD(8) System Manager's Manual XINETD(8)
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6 xinetd - the extended Internet services daemon
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9 xinetd [options]
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12 xinetd performs the same function as inetd: it starts programs that
13 provide Internet services. Instead of having such servers started at
14 system initialization time, and be dormant until a connection request
15 arrives, xinetd is the only daemon process started and it listens on
16 all service ports for the services listed in its configuration file.
17 When a request comes in, xinetd starts the appropriate server. Because
18 of the way it operates, xinetd (as well as inetd) is also referred to
19 as a super-server.
20 The services listed in xinetd's configuration file can be separated
22 into two groups. Services in the first group are called multi-threaded
23 and they require the forking of a new server process for each new con‐
24 nection request. The new server then handles that connection. For
25 such services, xinetd keeps listening for new requests so that it can
26 spawn new servers. On the other hand, the second group includes ser‐
27 vices for which the service daemon is responsible for handling all new
28 connection requests. Such services are called single-threaded and
29 xinetd will stop handling new requests for them until the server dies.
30 Services in this group are usually datagram-based.
31 So far, the only reason for the existence of a super-server was to con‐
33 serve system resources by avoiding to fork a lot of processes which
34 might be dormant for most of their lifetime. While fulfilling this
35 function, xinetd takes advantage of the idea of a super-server to pro‐
36 vide features such as access control and logging. Furthermore, xinetd
37 is not limited to services listed in /etc/services. Therefore, anybody
38 can use xinetd to start special-purpose servers.
39
41 -d Enables debug mode. This produces a lot of debugging output, and
42 it makes it possible to use a debugger on xinetd.
43 -syslog syslog_facility
45 This option enables syslog logging of xinetd-produced messages
46 using the specified syslog facility. The following facility
47 names are supported: daemon, auth, user, local[0-7] (check sys‐
48 log.conf(5) for their meanings). This option is ineffective in
49 debug mode since all relevant messages are sent to the terminal.
50 -filelog logfile
52 xinetd-produced messages will be placed in the specified file.
53 Messages are always appended to the file. If the file does not
54 exist, it will be created. This option is ineffective in debug
55 mode since all relevant messages are sent to the terminal.
56 -f config_file
58 Determines the file that xinetd uses for configuration. The
59 default is /etc/xinetd.conf.
60 -pidfile pid_file
62 The process ID is written to the file. This option is ineffec‐
63 tive in debug mode.
64 -dontfork
66 Tells xinetd to stay in the foreground rather than detaching
67 itself, to support being run from init or daemontools. This
68 option automatically sets -stayalive (see below).
69 -stayalive
71 Tells xinetd to stay running even if no services are specified.
72 -limit proc_limit
74 This option places a limit on the number of concurrently running
75 processes that can be started by xinetd. Its purpose is to pre‐
76 vent process table overflows.
77 -logprocs limit
79 This option places a limit on the number of concurrently running
80 servers for remote userid acquisition.
81 -version
83 This option causes xinetd to print out its version information.
84 -inetd_compat
86 This option causes xinetd to read /etc/inetd.conf in addition to
87 the standard xinetd config files. /etc/inetd.conf is read after
88 the standard xinetd config files.
89 -cc interval
91 This option instructs xinetd to perform periodic consistency
92 checks on its internal state every interval seconds.
93 The syslog and filelog options are mutually exclusive. If none is
95 specified, the default is syslog using the daemon facility. You should
96 not confuse xinetd messages with messages related to service logging.
97 The latter are logged only if this is specified via the configuration
98 file.
99
101 xinetd performs certain actions when it receives certain signals. The
102 actions associated with the specific signals can be redefined by edit‐
103 ing config.h and recompiling.
104 SIGHUP causes a hard reconfiguration, which means that xinetd
106 re-reads the configuration file and terminates the
107 servers for services that are no longer available.
108 Access control is performed again on running servers by
109 checking the remote location, access times and server
110 instances. If the number of server instances is lowered,
111 some arbitrarily picked servers will be killed to sat‐
112 isfy the limit; this will happen after any servers are
113 terminated because of failing the remote location or
114 access time checks. Also, if the INTERCEPT flag was
115 clear and is set, any running servers for that service
116 will be terminated; the purpose of this is to ensure
117 that after a hard reconfiguration there will be no run‐
118 ning servers that can accept packets from addresses that
119 do not meet the access control criteria.
120 SIGQUIT causes program termination.
122 SIGTERM terminates all running servers before terminating
124 xinetd.
125 SIGUSR1 causes an internal state dump (the default dump file is
127 /var/run/xinetd.dump; to change the filename, edit con‐
128 fig.h and recompile).
129 SIGIOT causes an internal consistency check to verify that the
131 data structures used by the program have not been cor‐
132 rupted. When the check is completed xinetd will gener‐
133 ate a message that says if the check was successful or
134 not.
135 On reconfiguration the log files are closed and reopened. This allows
137 removal of old log files.
138
140 /etc/xinetd.conf default configuration file
141 /var/run/xinetd.dump
142 default dump file
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145 inetd(8),
146 xinetd.conf(5),
148 xinetd.log(5)
150 http://cr.yp.to/daemontools.html
152
154 Panos Tsirigotis, CS Dept, University of Colorado, Boulder Rob Braun
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157 zy-net-d
158 14 June 2001 XINETD(8)