403 lines
13 KiB
Groff
403 lines
13 KiB
Groff
.\" $NetBSD: inetd.8,v 1.16 1998/06/08 12:41:44 lukem Exp $
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.\"
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.\" Copyright (c) 1998 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
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.\" NASA Ames Research Center.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgment:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" Copyright (c) 1985, 1991 The Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)inetd.8 8.4 (Berkeley) 6/1/94
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.\"
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.Dd March 16, 1991
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.Dt INETD 8
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.Os BSD 4.3
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.Sh NAME
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.Nm inetd ,
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.Nm inetd.conf
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.Nd internet
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.Dq super-server
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.Sh SYNOPSIS
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.Nm
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.Op Fl d
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.Op Fl l
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.Op Ar configuration file
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.Sh DESCRIPTION
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.Nm
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should be run at boot time by
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.Pa /etc/rc
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(see
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.Xr rc 8 ) .
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It then listens for connections on certain
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internet sockets. When a connection is found on one
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of its sockets, it decides what service the socket
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corresponds to, and invokes a program to service the request.
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After the program is
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finished, it continues to listen on the socket (except in some cases which
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will be described below). Essentially,
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.Nm
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allows running one daemon to invoke several others,
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reducing load on the system.
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.Pp
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The options available for
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.\" Why doesn't just `.Nm :' work?
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.Nm "" :
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.Bl -tag -width Ds
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.It Fl d
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Turns on debugging.
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.El
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.Pp
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.Bl -tag -width Ds
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.It Fl l
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Turns on libwrap connection logging.
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.El
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.Pp
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Upon execution,
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.Nm
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reads its configuration information from a configuration
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file which, by default, is
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.Pa /etc/inetd.conf .
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There must be an entry for each field of the configuration
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file, with entries for each field separated by a tab or
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a space. Comments are denoted by a ``#'' at the beginning
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of a line. There must be an entry for each field (except for one
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special case, described below). The
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fields of the configuration file are as follows:
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.Pp
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.Bd -unfilled -offset indent -compact
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service name
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socket type
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protocol[,sndbuf=size][,rcvbuf=size]
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wait/nowait[.max]
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user[.group]
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server program
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server program arguments
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.Ed
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.Pp
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To specify an
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.Em Sun-RPC
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based service, the entry would contain these fields.
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.Pp
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.Bd -unfilled -offset indent -compact
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service name/version
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socket type
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rpc/protocol[,sndbuf=size][,rcvbuf=size]
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wait/nowait[.max]
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user[.group]
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server program
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server program arguments
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.Ed
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.Pp
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For Internet services, the first field of the line may also have a host
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address specifier prefixed to it, separated from the service name by a
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colon. If this is done, the string before the colon in the first field
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indiciates what local address
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.Nm
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should use when listening for that service, or the single character
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.Dq \&*
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to indicate
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.Dv INADDR_ANY ,
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meaning
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.Sq all local addresses .
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To avoid repeating an address that occurs frequently, a line with a
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host address specifier and colon, but no further fields, causes the
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host address specifier to be remembered and used for all further lines
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with no explicit host specifier (until another such line or the end of
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the file). A line
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.Dl *:
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is implicitly provided at the top of the file; thus, traditional
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configuration files (which have no host address specifiers) will be
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interpreted in the traditional manner, with all services listened for
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on all local addresses.
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.Pp
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The
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.Em service-name
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entry is the name of a valid service in
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the file
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.Pa /etc/services .
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For
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.Dq internal
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services (discussed below), the service
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name
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.Em must
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be the official name of the service (that is, the first entry in
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.Pa /etc/services ) .
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When used to specify a
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.Em Sun-RPC
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based service, this field is a valid RPC service name in
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the file
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.Pa /etc/rpc .
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The part on the right of the
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.Dq /
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is the RPC version number. This
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can simply be a single numeric argument or a range of versions.
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A range is bounded by the low version to the high version \-
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.Dq rusers/1-3 .
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.Pp
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The
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.Em socket-type
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should be one of
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.Dq stream ,
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.Dq dgram ,
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.Dq raw ,
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.Dq rdm ,
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or
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.Dq seqpacket ,
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depending on whether the socket is a stream, datagram, raw,
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reliably delivered message, or sequenced packet socket.
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.Pp
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The
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.Em protocol
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must be a valid protocol as given in
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.Pa /etc/protocols .
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Examples might be
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.Dq tcp
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or
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.Dq udp .
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Rpc based services are specified with the
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.Dq rpc/tcp
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or
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.Dq rpc/udp
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service type.
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.Pp
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In addition to the protocol, the configuration file may specify the
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send and receive socket buffer sizes for the listening socket. This
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is especially useful for TCP as the window scale factor, which is based on
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the receive socket buffer size, is advertised when the connection handshake
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occurs, thus the socket buffer size for the server must be set on the listen
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socket. By increasing the socket buffer sizes, better TCP performance may
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be realized in some situations. The socket buffer sizes are specified by
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appending their values to the protocol specification
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as follows:
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.Bd -literal -offset indent
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tcp,rcvbuf=16384
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tcp,sndbuf=64k
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tcp,rcvbuf=64k,sndbuf=1m
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.Ed
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.Pp
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A literal value may be specified, or modified using
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.Sq k
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to indicate kilobytes or
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.Sq m
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to indicate megabytes. Socket buffer sizes may be specified for all
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services and protocols except for tcpmux services.
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.Pp
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The
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.Em wait/nowait
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entry is used to tell
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.Nm
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if it should wait for the server program to return,
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or continue processing connections on the socket.
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If a datagram server connects
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to its peer, freeing the socket so
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.Nm
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can receive further messages on the socket, it is said to be
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a
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.Dq multi-threaded
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server, and should use the
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.Dq nowait
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entry. For datagram servers which process all incoming datagrams
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on a socket and eventually time out, the server is said to be
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.Dq single-threaded
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and should use a
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.Dq wait
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entry.
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.Xr comsat 8
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.Pq Xr biff 1
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and
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.Xr talkd 8
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are both examples of the latter type of
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datagram server.
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.Xr tftpd 8
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is an exception; it is a datagram server that establishes pseudo-connections.
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It must be listed as
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.Dq wait
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in order to avoid a race;
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the server reads the first packet, creates a new socket,
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and then forks and exits to allow
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.Nm
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to check for new service requests to spawn new servers.
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The optional
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.Dq max
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suffix (separated from
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.Dq wait
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or
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.Dq nowait
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by a dot) specifies the maximum number of server instances that may be
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spawned from
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.Nm
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within an interval of 60 seconds. When omitted,
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.Dq max
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defaults to 40.
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.Pp
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Stream servers are usually marked as
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.Dq nowait
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but if a single server process is to handle multiple connections, it may be
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marked as
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.Dq wait .
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The master socket will then be passed as fd 0 to the server, which will then
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need to accept the incoming connection. The server should eventually time
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out and exit when no more connections are active.
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.Nm
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will continue to
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listen on the master socket for connections, so the server should not close
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it when it exits.
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.Xr identd 8
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is usually the only stream server marked as wait.
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.Pp
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The
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.Em user
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entry should contain the user name of the user as whom the server
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should run. This allows for servers to be given less permission
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than root. An optional group name can be specified by appending a dot to
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the user name followed by the group name. This allows for servers to run with
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a different (primary) group id than specified in the password file. If a group
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is specified and user is not root, the supplementary groups associated with
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that user will still be set.
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.Pp
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The
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.Em server-program
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entry should contain the pathname of the program which is to be
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executed by
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.Nm
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when a request is found on its socket. If
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.Nm
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provides this service internally, this entry should
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be
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.Dq internal .
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.Pp
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The
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.Em server program arguments
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should be just as arguments
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normally are, starting with argv[0], which is the name of
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the program. If the service is provided internally, the
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word
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.Dq internal
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should take the place of this entry.
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.Pp
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.Nm
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provides several
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.Dq trivial
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services internally by use of
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routines within itself. These services are
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.Dq echo ,
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.Dq discard ,
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.Dq chargen
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(character generator),
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.Dq daytime
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(human readable time), and
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.Dq time
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(machine readable time,
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in the form of the number of seconds since midnight, January
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1, 1900). For details of these services, consult the appropriate
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.Tn RFC
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from the Network Information Center.
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.Pp
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.Nm
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rereads its configuration file when it receives a hangup signal,
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.Dv SIGHUP .
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Services may be added, deleted or modified when the configuration file
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is reread.
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.Nm
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creates a file
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.Em /var/run/inetd.pid
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that contains its process identifier.
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.Sh BUGS
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Host address specifiers, while they make conceptual sense for RPC
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services, do not work entirely correctly. This is largely because the
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portmapper interface does not provide a way to register different ports
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for the same service on different local addresses. Provided you never
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have more than one entry for a given RPC service, everything should
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work correctly. (Note that default host address specifiers do apply to
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RPC lines with no explicit specifier.)
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.Sh SEE ALSO
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.Xr comsat 8 ,
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.Xr fingerd 8 ,
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.Xr ftpd 8 ,
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.Xr rexecd 8 ,
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.Xr rlogind 8 ,
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.Xr rshd 8 ,
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.Xr telnetd 8 ,
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.Xr tftpd 8 ,
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.Xr hosts_access 5 ,
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.Xr hosts_options 5
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.Sh HISTORY
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The
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.Nm
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command appeared in
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.Bx 4.3 .
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Support for
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.Em Sun-RPC
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based services is modeled after that
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provided by SunOS 4.1.
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Support for specifying the socket buffer sizes was added in
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.Nx 1.4 .
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.Sh SECURITY CONSIDERATIONS
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Enabling the
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.Dq echo ,
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.Dq discard ,
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and
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.Dq chargen
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built-in trivial services is not recommended because remote
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users may abuse these to cause a denial of network service to
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or from the local host.
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