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.\" Hey, Emacs! This is an -*- nroff -*- source file.
.\" Authors: Ian Jackson
.\"
.\" authbind is Copyright (C) 1998 Ian Jackson
.\"
.\" This program is free software; you can redistribute it and/or modify
.\" it under the terms of the GNU General Public License as published by
.\" the Free Software Foundation; either version 2, or (at your option)
.\" any later version.
.\"
.\" This program is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public License
.\" along with this program; if not, write to the Free Software Foundation,
.\" Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
.\"
.TH AUTHBIND\-HELPER 8 "30th August 1998" "Debian Project" "Debian Linux manual"
.br
.SH NAME
authbind\-helper \- helper program to bind sockets to privileged ports without root
.SH SYNOPSIS
.BI /usr/lib/authbind/helper " addr4\-hex port\-hex " < socket
.br
.BI /usr/lib/authbind/helper " addr6\-hex port\-hex 6 " < socket
.SH DESCRIPTION
.B helper
is the program used by
.BR libauthbind ,
which is in turn used by
.B authbind
to allow programs which do not or should not run as root to bind to
low-numbered ports in a controlled way. See
.BR authbind (1).
.PP
It may also be used standalone, i.e. without assistance from
.BR authbind .
Its standard input should be a TCP/IP socket, and it should be passed
two or three arguments.
.PP
The arguments are the address and port number, respectively, to which
the caller desires that the socket be bound, and the address family
(ommitted for IPv4; the fixed string
.B 6
for IPv6).
.I addr4-hex
and
.I port-hex
should be hex strings,
.I without
leading
.BR 0x ,
of exactly the right length (8 and 4 digits, respectively), being
a pair of hex digits for each byte in the address or port number when
expressed in host byte order. For example, the port argument is the
result of something like
.B sprintf(arg,
.B """%04X"",
.BR sin.sin_port) .
.I addr6-hex
should be a string of 32 hex digits, being a pair for each byte in
the address, in network byte order.
.SH EXIT STATUS
.B helper
will exit with code 0 on success.
.PP
If possible,
.B helper
will return an appropriate
.B errno
value as its exit status. If this is not possible it may exit with
status 255 or with an exit status corresponding to
.B ENOSYS
.RI ( "Function not implemented" ).
.SH ACCESS CONTROL
See
.BR authbind (1)
for details of the access control regime implemented by
.BR helper .
.SH SEE ALSO
.BR authbind (1),
.BR bind (2)
.SH AUTHOR
.B authbind
and this manpage were written by Ian Jackson. They are
Copyright (C)1998,2012
by him and released under the GNU General Public Licence; there is NO
WARRANTY. See
.B /usr/doc/authbind/copyright
and
.B /usr/doc/copyright/GPL
for details.
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