1.\" $OpenBSD: inetd.8,v 1.34 2009/12/29 10:25:43 sobrado Exp $ 2.\" Copyright (c) 1985, 1991 The Regents of the University of California. 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. Neither the name of the University nor the names of its contributors 14.\" may be used to endorse or promote products derived from this software 15.\" without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.\" from: @(#)inetd.8 6.7 (Berkeley) 3/16/91 30.\" 31.Dd $Mdocdate: December 29 2009 $ 32.Dt INETD 8 33.Os 34.Sh NAME 35.Nm inetd 36.Nd internet 37.Dq super-server 38.Sh SYNOPSIS 39.Nm inetd 40.Op Fl d 41.Op Fl R Ar rate 42.Op Ar configuration_file 43.Sh DESCRIPTION 44.Nm inetd 45should be run at boot time by 46.Pa /etc/rc 47(see 48.Xr rc 8 ) . 49It then listens for connections on certain internet sockets. 50When a connection is found on one 51of its sockets, it decides what service the socket 52corresponds to, and invokes a program to service the request. 53After the program is 54finished, it continues to listen on the socket (except in some cases which 55will be described below). 56Essentially, 57.Nm inetd 58allows running one daemon to invoke several others, 59reducing load on the system. 60.Pp 61The options are as follows: 62.Bl -tag -width Ds 63.It Fl d 64Turns on debugging. 65.It Fl R Ar rate 66Specify the maximum number of times a service can be invoked 67in one minute; the default is 256. 68If a service exceeds this limit, 69.Nm 70will log the problem 71and stop servicing requests for the specific service for ten minutes. 72See also the wait/nowait configuration fields below. 73.El 74.Pp 75Upon execution, 76.Nm inetd 77reads its configuration information from a configuration 78file which, by default, is 79.Pa /etc/inetd.conf . 80There must be an entry for each field of the configuration 81file, with entries for each field separated by a tab or 82a space. 83Comments are denoted by a 84.Dq # 85at the beginning 86of a line. 87The fields of the configuration file are as follows: 88.Bd -unfilled -offset indent 89service name 90socket type 91protocol 92wait/nowait[.max] 93user[.group] or user[:group] 94server program 95server program arguments 96.Ed 97.Pp 98To specify a Sun-RPC 99based service, the entry would contain these fields. 100.Bd -unfilled -offset indent 101service name/version 102socket type 103rpc/protocol 104wait/nowait[.max] 105user[.group] or user[:group] 106server program 107server program arguments 108.Ed 109.Pp 110For internet services, the first field of the line may also have a host 111address specifier prefixed to it, separated from the service name by a 112colon. 113If this is done, the string before the colon in the first field 114indicates what local address 115.Nm 116should use when listening for that service. 117Multiple local addresses 118can be specified on the same line, separated by commas. 119Numeric IP 120addresses in dotted-quad notation can be used as well as symbolic 121hostnames. 122Symbolic hostnames are looked up using 123.Fn gethostbyname . 124If a hostname has multiple address mappings, inetd creates a socket 125to listen on each address. 126.Pp 127The single character 128.Dq \&* 129indicates 130.Dv INADDR_ANY , 131meaning 132.Dq all local addresses . 133To avoid repeating an address that occurs frequently, a line with a 134host address specifier and colon, but no further fields, causes the 135host address specifier to be remembered and used for all further lines 136with no explicit host specifier (until another such line or the end of 137the file). 138A line 139.Dl *: 140is implicitly provided at the top of the file; thus, traditional 141configuration files (which have no host address specifiers) will be 142interpreted in the traditional manner, with all services listened for 143on all local addresses. 144If the protocol is 145.Dq unix , 146this value is ignored. 147.Pp 148The 149.Em service name 150entry is the name of a valid service in 151the file 152.Pa /etc/services . 153For 154.Dq internal 155services (discussed below), the service 156name 157.Em must 158be the official name of the service (that is, the first entry in 159.Pa /etc/services ) . 160When used to specify a Sun-RPC 161based service, this field is a valid RPC service name in 162the file 163.Pa /etc/rpc . 164The part on the right of the 165.Dq / 166is the RPC version number. 167This can simply be a single numeric argument or a range of versions. 168A range is bounded by the low version to the high version - 169.Dq rusers/1-3 . 170For 171.Ux Ns -domain 172sockets this field specifies the path name of the socket. 173.Pp 174The 175.Em socket type 176should be one of 177.Dq stream , 178.Dq dgram , 179.Dq raw , 180.Dq rdm , 181or 182.Dq seqpacket , 183depending on whether the socket is a stream, datagram, raw, 184reliably delivered message, or sequenced packet socket. 185.Pp 186The 187.Em protocol 188must be a valid protocol as given in 189.Pa /etc/protocols . 190Examples might be 191.Dq tcp 192or 193.Dq udp . 194RPC based services are specified with the 195.Dq rpc/tcp 196or 197.Dq rpc/udp 198service type. 199.Dq tcp 200and 201.Dq udp 202will be recognized as 203.Dq TCP or UDP over default IP version . 204This is currently IPv4, but in the future it will be IPv6. 205If you need to specify IPv4 or IPv6 explicitly, use something like 206.Dq tcp4 207or 208.Dq udp6 . 209A 210.Em protocol 211of 212.Dq unix 213is used to specify a socket in the 214.Ux Ns -domain . 215.Pp 216The 217.Em wait/nowait 218entry is used to tell 219.Nm 220if it should wait for the server program to return, 221or continue processing connections on the socket. 222If a datagram server connects 223to its peer, freeing the socket so 224.Nm inetd 225can receive further messages on the socket, it is said to be 226a 227.Dq multi-threaded 228server, and should use the 229.Dq nowait 230entry. 231For datagram servers which process all incoming datagrams 232on a socket and eventually time out, the server is said to be 233.Dq single-threaded 234and should use a 235.Dq wait 236entry. 237.Xr comsat 8 238.Pq Xr biff 1 239and 240.Xr talkd 8 241are both examples of the latter type of 242datagram server. 243.Xr tftpd 8 244is an exception; it is a datagram server that establishes pseudo-connections. 245It must be listed as 246.Dq wait 247in order to avoid a race; 248the server reads the first packet, creates a new socket, 249and then forks and exits to allow 250.Nm inetd 251to check for new service requests to spawn new servers. 252The optional 253.Dq max 254suffix (separated from 255.Dq wait 256or 257.Dq nowait 258by a dot) specifies the maximum number of times a service can be invoked 259in one minute; the default is 256. 260If a service exceeds this limit, 261.Nm 262will log the problem 263and stop servicing requests for the specific service for ten minutes. 264See also the 265.Fl R 266option above. 267.Pp 268Stream servers are usually marked as 269.Dq nowait 270but if a single server process is to handle multiple connections, it may be 271marked as 272.Dq wait . 273The master socket will then be passed as fd 0 to the server, which will then 274need to accept the incoming connection. 275The server should eventually time 276out and exit when no more connections are active. 277.Nm 278will continue to 279listen on the master socket for connections, so the server should not close 280it when it exits. 281.Pp 282The 283.Em user 284entry should contain the user name of the user as whom the server 285should run. 286This allows for servers to be given less permission 287than root. 288An optional group name can be specified by appending a dot to 289the user name followed by the group name. 290This allows for servers to run with 291a different (primary) group ID than specified in the password file. 292If a group 293is specified and user is not root, the supplementary groups associated with 294that user will still be set. 295.Pp 296The 297.Em server program 298entry should contain the pathname of the program which is to be 299executed by 300.Nm inetd 301when a request is found on its socket. 302If 303.Nm inetd 304provides this service internally, this entry should 305be 306.Dq internal . 307.Pp 308The 309.Em server program arguments 310should be just as arguments 311normally are, starting with argv[0], which is the name of 312the program. 313If the service is provided internally, the word 314.Dq internal 315should take the place of this entry. 316.Pp 317.Nm inetd 318provides several 319.Dq trivial 320services internally by use of routines within itself. 321These services are 322.Dq echo , 323.Dq discard , 324.Dq chargen 325(character generator), 326.Dq daytime 327(human readable time), and 328.Dq time 329(machine readable time, 330in the form of the number of seconds since midnight, January 3311, 1900). 332All of these services are TCP based. 333For details of these services, consult the appropriate 334.Tn RFC 335from the Network Information Center. 336.Pp 337.Nm inetd 338rereads its configuration file when it receives a hangup signal, 339.Dv SIGHUP . 340Services may be added, deleted or modified when the configuration file 341is reread. 342.Nm inetd 343creates a file 344.Em /var/run/inetd.pid 345that contains its process identifier. 346.Ss IPv6 TCP/UDP behavior 347If you wish to run a server for IPv4 and IPv6 traffic, 348you'll need to run two separate processes for the same server program, 349specified as two separate lines in 350.Pa inetd.conf , 351for 352.Dq tcp4 353and 354.Dq tcp6 . 355.Pp 356Under various combinations of IPv4/v6 daemon settings, 357.Nm 358will behave as follows: 359.Bl -bullet -compact 360.It 361If you have only one server on 362.Dq tcp4 , 363IPv4 traffic will be routed to the server. 364IPv6 traffic will not be accepted. 365.It 366If you have two servers on 367.Dq tcp4 368and 369.Dq tcp6 , 370IPv4 traffic will be routed to the server on 371.Dq tcp4 , 372and IPv6 traffic will go to server on 373.Dq tcp6 . 374.It 375If you have only one server on 376.Dq tcp6 , 377only IPv6 traffic will be routed to the server. 378.El 379.Sh SEE ALSO 380.Xr comsat 8 , 381.Xr fingerd 8 , 382.Xr ftp-proxy 8 , 383.Xr ftpd 8 , 384.Xr identd 8 , 385.Xr rshd 8 , 386.Xr talkd 8 , 387.Xr tftpd 8 388.Sh HISTORY 389The 390.Nm 391command appeared in 392.Bx 4.3 . 393Support for Sun-RPC 394based services is modelled after that 395provided by SunOS 4.1. 396IPv6 support was added by the KAME project in 1999. 397.Sh BUGS 398Host address specifiers, while they make conceptual sense for RPC 399services, do not work entirely correctly. 400This is largely because the 401portmapper interface does not provide a way to register different ports 402for the same service on different local addresses. 403Provided you never 404have more than one entry for a given RPC service, everything should 405work correctly. 406(Note that default host address specifiers do apply to 407RPC lines with no explicit specifier.) 408