224 lines
5.8 KiB
Groff
224 lines
5.8 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. 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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.\" @(#)tftpd.8 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd September 14, 2000
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.Dt TFTPD 8
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.Os
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.Sh NAME
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.Nm tftpd
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.Nd Internet Trivial File Transfer Protocol server
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.Sh SYNOPSIS
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.Nm tftpd
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.Op Fl cClnw
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.Op Fl s Ar directory
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.Op Fl u Ar user
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.Op Fl U Ar umask
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.Op Ar directory ...
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.Sh DESCRIPTION
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The
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.Nm
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utility is a server which supports the
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Internet Trivial File Transfer
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Protocol
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.Pq Tn RFC 1350 .
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The
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.Tn TFTP
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server operates
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at the port indicated in the
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.Ql tftp
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service description;
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see
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.Xr services 5 .
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The server is normally started by
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.Xr inetd 8 .
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.Pp
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The use of
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.Xr tftp 1
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does not require an account or password on the remote system.
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Due to the lack of authentication information,
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.Nm
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will allow only publicly readable files to be
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accessed.
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Files containing the string
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.Dq Li "/../"
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or starting with
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.Dq Li "../"
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are not allowed.
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Files may be written only if they already exist and are publicly writable.
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Note that this extends the concept of
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.Dq public
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to include
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all users on all hosts that can be reached through the network;
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this may not be appropriate on all systems, and its implications
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should be considered before enabling tftp service.
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The server should have the user ID with the lowest possible privilege.
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.Pp
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Access to files may be restricted by invoking
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.Nm
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with a list of directories by including up to 20 pathnames
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as server program arguments in
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.Xr inetd.conf 5 .
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In this case access is restricted to files whose
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names are prefixed by the one of the given directories.
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The given directories are also treated as a search path for
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relative filename requests.
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.Pp
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The
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.Fl s
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option provides additional security by changing
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the root directory of
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.Nm ,
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thereby prohibiting accesses to outside of the specified
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.Ar directory .
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Because
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.Xr chroot 2
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requires super-user privileges,
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.Nm
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must be run as
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.Li root .
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However, after performing the
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.Xr chroot 2
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call,
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.Nm
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will set its user ID to that of the specified
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.Ar user ,
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or
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.Dq Li nobody
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if no
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.Fl u
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option is specified.
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.Pp
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The options are:
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.Bl -tag -width Ds
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.It Fl c
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Changes the default root directory of a connecting host via
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.Xr chroot 2
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based on the connecting IP address.
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This prevents multiple clients from writing to the same file at the same time.
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If the directory does not exist, the client connection is refused.
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The
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.Fl s
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option is required for
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.Fl c
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and the specified
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.Ar directory
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is used as a base.
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.It Fl C
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Operates the same as
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.Fl c
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except it falls back to
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.Ar directory
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specified via
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.Fl s
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if a directory does not exist for the client's IP.
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.It Fl l
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Log all requests using
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.Xr syslog 3
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with the facility of
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.Dv LOG_FTP .
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.Sy Note :
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Logging of
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.Dv LOG_FTP
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messages
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must also be enabled in the syslog configuration file,
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.Xr syslog.conf 5 .
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.It Fl n
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Suppress negative acknowledgement of requests for nonexistent
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relative filenames.
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.It Fl s Ar directory
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Cause
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.Nm
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to change its root directory to
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.Ar directory .
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After doing that but before accepting commands,
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.Nm
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will switch credentials to an unprivileged user.
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.It Fl u Ar user
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Switch credentials to
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.Ar user
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(default
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.Dq Li nobody )
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when the
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.Fl s
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option is used.
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The user must be specified by name, not a numeric UID.
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.It Fl U Ar umask
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Set the
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.Ar umask
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for newly created files.
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The default is 022
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.Pq Dv S_IWGRP | S_IWOTH .
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.It Fl w
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Allow writes requests to create new files.
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By default
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.Nm
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requires that the file specified in a write request exist.
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.El
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.Sh SEE ALSO
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.Xr tftp 1 ,
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.Xr chroot 2 ,
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.Xr syslog 3 ,
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.Xr inetd.conf 5 ,
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.Xr services 5 ,
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.Xr syslog.conf 5 ,
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.Xr inetd 8
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.Rs
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.%A K. R. Sollins
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.%T The TFTP Protocol (Revision 2)
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.%D July 1992
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.%O RFC 1350, STD 33
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.Re
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Bx 4.2 ;
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the
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.Fl s
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option was introduced in
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.Fx 2.2 ,
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the
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.Fl u
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option was introduced in
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.Fx 4.2 ,
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and the
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.Fl c
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option was introduced in
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.Fx 4.3 .
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.Sh BUGS
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Files larger than 33488896 octets (65535 blocks) cannot be transferred
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without client and server supporting blocksize negotiation (RFC1783).
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.Pp
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Many tftp clients will not transfer files over 16744448 octets (32767 blocks).
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