IABSD.fr/src/usr.sbin/inetd/inetd.8

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• Author : schwarze
  Date : 2020-02-10 13:18:20
  Hash : c9d6433d
  Message : briefly mention /etc/examples/ in the FILES section of all the manual pages that document the corresponding configuration files; OK jmc@, and general direction discussed with many

• usr.sbin/inetd/inetd.8

• .\"	$OpenBSD: inetd.8,v 1.42 2020/02/10 13:18:21 schwarze Exp $
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  .\"     from: @(#)inetd.8	6.7 (Berkeley) 3/16/91
  .\"
  .Dd $Mdocdate: February 10 2020 $
  .Dt INETD 8
  .Os
  .Sh NAME
  .Nm inetd ,
  .Nm inetd.conf
  .Nd internet super-server
  .Sh SYNOPSIS
  .Nm inetd
  .Op Fl d
  .Op Fl R Ar rate
  .Op Ar configuration_file
  .Sh DESCRIPTION
  .Nm inetd
  should be run at boot time by
  .Pa /etc/rc
  (see
  .Xr rc 8 ) .
  It then listens for connections on certain internet sockets.
  When a connection is found on one
  of its sockets, it decides what service the socket
  corresponds to, and invokes a program to service the request.
  After the program is
  finished, it continues to listen on the socket (except in some cases which
  will be described below).
  Essentially,
  .Nm inetd
  allows running one daemon to invoke several others,
  reducing load on the system.
  .Pp
  The options are as follows:
  .Bl -tag -width Ds
  .It Fl d
  Turns on debugging.
  .It Fl R Ar rate
  Specify the maximum number of times a service can be invoked
  in one minute; the default is 256.
  If a service exceeds this limit,
  .Nm
  will log the problem
  and stop servicing requests for the specific service for ten minutes.
  See also the wait/nowait configuration fields below.
  .El
  .Pp
  Upon execution,
  .Nm inetd
  reads its configuration information from a configuration
  file which, by default, is
  .Pa /etc/inetd.conf .
  There must be an entry for each field of the configuration
  file, with entries for each field separated by a tab or
  a space.
  Comments are denoted by a
  .Dq #
  at the beginning
  of a line.
  The fields of the configuration file are as follows:
  .Bd -unfilled -offset indent
  service name
  socket type
  protocol
  wait/nowait[.max]
  user[.group] or user[:group]
  server program
  server program arguments
  .Ed
  .Pp
  To specify a Sun-RPC
  based service, the entry would contain these fields.
  .Bd -unfilled -offset indent
  service name/version
  socket type
  rpc/protocol
  wait/nowait[.max]
  user[.group] or user[:group]
  server program
  server program arguments
  .Ed
  .Pp
  For internet services, the first field of the line may also have a host
  address specifier prefixed to it, separated from the service name by a
  colon.
  If this is done, the string before the colon in the first field
  indicates what local address
  .Nm
  should use when listening for that service.
  Multiple local addresses
  can be specified on the same line, separated by commas.
  Numeric IP
  addresses in dotted-quad notation can be used as well as symbolic
  hostnames.
  Symbolic hostnames are looked up using
  .Fn getaddrinfo .
  If a hostname has multiple address mappings, inetd creates a socket
  to listen on each address.
  .Pp
  The single character
  .Dq \&*
  indicates
  .Dv INADDR_ANY ,
  meaning
  .Dq all local addresses .
  To avoid repeating an address that occurs frequently, a line with a
  host address specifier and colon, but no further fields, causes the
  host address specifier to be remembered and used for all further lines
  with no explicit host specifier (until another such line or the end of
  the file).
  A line
  .Dl *:
  is implicitly provided at the top of the file; thus, traditional
  configuration files (which have no host address specifiers) will be
  interpreted in the traditional manner, with all services listened for
  on all local addresses.
  If the protocol is
  .Dq unix ,
  this value is ignored.
  .Pp
  The
  .Em service name
  entry is the name of a valid service in
  the file
  .Pa /etc/services .
  For
  .Dq internal
  services (discussed below), the service
  name
  .Em must
  be the official name of the service (that is, the first entry in
  .Pa /etc/services ) .
  When used to specify a Sun-RPC
  based service, this field is a valid RPC service name in
  the file
  .Pa /etc/rpc .
  The part on the right of the
  .Dq /
  is the RPC version number.
  This can simply be a single numeric argument or a range of versions.
  A range is bounded by the low version to the high version -
  .Dq rusers/1-3 .
  For
  .Ux Ns -domain
  sockets this field specifies the path name of the socket.
  .Pp
  The
  .Em socket type
  should be one of
  .Dq stream
  or
  .Dq dgram ,
  depending on whether the socket is a stream or datagram socket.
  .Pp
  The
  .Em protocol
  must be a valid protocol as given in
  .Pa /etc/protocols .
  Examples might be
  .Dq tcp
  or
  .Dq udp .
  RPC based services are specified with the
  .Dq rpc/tcp
  or
  .Dq rpc/udp
  service type.
  .Dq tcp
  and
  .Dq udp
  will be recognized as
  .Dq TCP or UDP over default IP version .
  This is currently IPv4, but in the future it will be IPv6.
  If you need to specify IPv4 or IPv6 explicitly, use something like
  .Dq tcp4
  or
  .Dq udp6 .
  A
  .Em protocol
  of
  .Dq unix
  is used to specify a socket in the
  .Ux Ns -domain .
  .Pp
  The
  .Em wait/nowait
  entry is used to tell
  .Nm
  if it should wait for the server program to return,
  or continue processing connections on the socket.
  If a datagram server connects
  to its peer, freeing the socket so
  .Nm inetd
  can receive further messages on the socket, it is said to be
  a
  .Dq multi-threaded
  server, and should use the
  .Dq nowait
  entry.
  For datagram servers which process all incoming datagrams
  on a socket and eventually time out, the server is said to be
  .Dq single-threaded
  and should use a
  .Dq wait
  entry.
  .Xr comsat 8
  .Pq Xr biff 1
  and
  .Xr talkd 8
  are both examples of the latter type of
  datagram server.
  The optional
  .Dq max
  suffix (separated from
  .Dq wait
  or
  .Dq nowait
  by a dot) specifies the maximum number of times a service can be invoked
  in one minute; the default is 256.
  If a service exceeds this limit,
  .Nm
  will log the problem
  and stop servicing requests for the specific service for ten minutes.
  See also the
  .Fl R
  option above.
  .Pp
  Stream servers are usually marked as
  .Dq nowait
  but if a single server process is to handle multiple connections, it may be
  marked as
  .Dq wait .
  The master socket will then be passed as fd 0 to the server, which will then
  need to accept the incoming connection.
  The server should eventually time
  out and exit when no more connections are active.
  .Nm
  will continue to
  listen on the master socket for connections, so the server should not close
  it when it exits.
  .Pp
  The
  .Em user
  entry should contain the user name of the user as whom the server
  should run.
  This allows for servers to be given less permission
  than root.
  An optional group name can be specified by appending a dot to
  the user name followed by the group name.
  This allows for servers to run with
  a different (primary) group ID than specified in the password file.
  If a group
  is specified and user is not root, the supplementary groups associated with
  that user will still be set.
  .Pp
  The
  .Em server program
  entry should contain the pathname of the program which is to be
  executed by
  .Nm inetd
  when a request is found on its socket.
  If
  .Nm inetd
  provides this service internally, this entry should
  be
  .Dq internal .
  .Pp
  The
  .Em server program arguments
  should be just as arguments
  normally are, starting with argv[0], which is the name of
  the program.
  If the service is provided internally, the word
  .Dq internal
  should take the place of this entry.
  .Pp
  .Nm inetd
  provides several
  .Dq trivial
  services internally by use of routines within itself.
  These services are
  .Dq echo ,
  .Dq discard ,
  .Dq chargen
  (character generator),
  .Dq daytime
  (human readable time), and
  .Dq time
  (machine readable time,
  in the form of the number of seconds since midnight, January
  1, 1900).
  All of these services are TCP based.
  For details of these services, consult the appropriate RFC
  from the Network Information Center.
  .Pp
  .Nm inetd
  rereads its configuration file when it receives a hangup signal,
  .Dv SIGHUP .
  Services may be added, deleted or modified when the configuration file
  is reread.
  .Ss IPv6 TCP/UDP behavior
  If you wish to run a server for IPv4 and IPv6 traffic,
  you'll need to run two separate processes for the same server program,
  specified as two separate lines in
  .Pa inetd.conf ,
  for
  .Dq tcp4
  and
  .Dq tcp6 .
  .Pp
  Under various combinations of IPv4/v6 daemon settings,
  .Nm
  will behave as follows:
  .Bl -bullet -compact
  .It
  If you have only one server on
  .Dq tcp4 ,
  IPv4 traffic will be routed to the server.
  IPv6 traffic will not be accepted.
  .It
  If you have two servers on
  .Dq tcp4
  and
  .Dq tcp6 ,
  IPv4 traffic will be routed to the server on
  .Dq tcp4 ,
  and IPv6 traffic will go to server on
  .Dq tcp6 .
  .It
  If you have only one server on
  .Dq tcp6 ,
  only IPv6 traffic will be routed to the server.
  .El
  .Sh FILES
  .Bl -tag -width /etc/examples/inetd.conf -compact
  .It Pa /etc/inetd.conf
  .It Pa /etc/examples/inetd.conf
  .El
  .Sh SEE ALSO
  .Xr comsat 8 ,
  .Xr fingerd 8 ,
  .Xr ftp-proxy 8 ,
  .Xr ftpd 8 ,
  .Xr identd 8 ,
  .Xr talkd 8
  .Sh HISTORY
  The
  .Nm
  command appeared in
  .Bx 4.3 .
  Support for Sun-RPC
  based services is modelled after that
  provided by SunOS 4.1.
  IPv6 support was added by the KAME project in 1999.
  .Sh BUGS
  Host address specifiers, while they make conceptual sense for RPC
  services, do not work entirely correctly.
  This is largely because the
  portmapper interface does not provide a way to register different ports
  for the same service on different local addresses.
  Provided you never
  have more than one entry for a given RPC service, everything should
  work correctly.
  (Note that default host address specifiers do apply to
  RPC lines with no explicit specifier.)