808a36ef65
This will make a number of things easier in the future, as well as (finally!) avoiding the Id-smashing problem which has plagued developers for so long. Boy, I'm glad we're not using sup anymore. This update would have been insane otherwise.
380 lines
11 KiB
Groff
380 lines
11 KiB
Groff
.\" Copyright (c) 1985, 1988, 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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.\" @(#)ftpd.8 8.2 (Berkeley) 4/19/94
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.\" $FreeBSD$
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.\"
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.Dd April 19, 1994
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.Dt FTPD 8
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.Os BSD 4.2
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.Sh NAME
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.Nm ftpd
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.Nd
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Internet File Transfer Protocol server
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.Sh SYNOPSIS
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.Nm ftpd
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.Op Fl dl
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.Op Fl D
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.Op Fl R
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.Op Fl S
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.Op Fl U
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.Op Fl T Ar maxtimeout
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.Op Fl t Ar timeout
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.Op Fl a Ar address
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.Op Fl p Ar file
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.Sh DESCRIPTION
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.Nm Ftpd
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is the
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Internet File Transfer Protocol
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server process. The server uses the
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.Tn TCP
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protocol
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and listens at the port specified in the
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.Dq ftp
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service specification; see
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.Xr services 5 .
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.Pp
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Available options:
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.Bl -tag -width Ds
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.It Fl d
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Debugging information is written to the syslog using LOG_FTP.
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.It Fl l
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Each successful and failed
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.Xr ftp 1
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session is logged using syslog with a facility of LOG_FTP.
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If this option is specified twice, the retrieve (get), store (put), append,
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delete, make directory, remove directory and rename operations and
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their filename arguments are also logged. Note: LOG_FTP messages
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are not displayed by
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.Xr syslogd 8
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by default, and may have to be enabled in
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.Xr syslogd 8 Ns 's
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configuration file.
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.It Fl D
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With this option set,
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.Nm ftpd
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will detach and become a daemon, accepting connections on the FTP port and
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forking children processes to handle them. This is lower overhead than
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starting
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.Nm ftpd
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from
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.Xr inetd 8
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and is thus useful on busy servers to reduce load.
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.It Fl R
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With this option set,
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.Nm ftpd
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will revert to historical behavior with regard to security checks on
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user operations and restrictions on PORT requests.
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Currently,
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.Nm ftpd
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will only honor PORT commands directed to unprivileged ports on the
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remote user's host (which violates the FTP protocol specification but
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closes some security holes).
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.
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.It Fl S
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With this option set,
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.Nm ftpd
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logs all anonymous transfers to the file
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.Pa /var/log/ftpd
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when this file exists.
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.
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.It Fl U
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In previous versions of
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.Nm ftpd ,
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when a passive mode client requested a data connection to the server,
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the server would use data ports in the range 1024..4999. Now, by default,
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the server will use data ports in the range 40000..44999. Specifying this
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option will revert to the old behavior.
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.It Fl T
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A client may also request a different timeout period;
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the maximum period allowed may be set to
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.Ar timeout
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seconds with the
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.Fl T
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option.
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The default limit is 2 hours.
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.It Fl t
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The inactivity timeout period is set to
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.Ar timeout
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seconds (the default is 15 minutes).
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.It Fl a
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When
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.Fl D
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is specified, accept connections only on the specified
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.Ar address .
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.It Fl p
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When
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.Fl D
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is specified, write the daemon's process ID to
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.Ar file .
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.It Fl A
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Allow only anonymous ftp access
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.El
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.Pp
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The file
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.Pa /etc/nologin
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can be used to disable ftp access.
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If the file exists,
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.Nm
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displays it and exits.
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If the file
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.Pa /etc/ftpwelcome
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exists,
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.Nm
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prints it before issuing the
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.Dq ready
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message.
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If the file
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.Pa /etc/ftpmotd
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exists,
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.Nm
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prints it after a successful login.
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.Pp
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The ftp server currently supports the following ftp requests.
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The case of the requests is ignored.
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.Bl -column "Request" -offset indent
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.It Request Ta "Description"
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.It ABOR Ta "abort previous command"
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.It ACCT Ta "specify account (ignored)"
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.It ALLO Ta "allocate storage (vacuously)"
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.It APPE Ta "append to a file"
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.It CDUP Ta "change to parent of current working directory"
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.It CWD Ta "change working directory"
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.It DELE Ta "delete a file"
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.It HELP Ta "give help information"
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.It LIST Ta "give list files in a directory" Pq Dq Li "ls -lgA"
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.It MKD Ta "make a directory"
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.It MDTM Ta "show last modification time of file"
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.It MODE Ta "specify data transfer" Em mode
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.It NLST Ta "give name list of files in directory"
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.It NOOP Ta "do nothing"
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.It PASS Ta "specify password"
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.It PASV Ta "prepare for server-to-server transfer"
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.It PORT Ta "specify data connection port"
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.It PWD Ta "print the current working directory"
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.It QUIT Ta "terminate session"
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.It REST Ta "restart incomplete transfer"
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.It RETR Ta "retrieve a file"
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.It RMD Ta "remove a directory"
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.It RNFR Ta "specify rename-from file name"
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.It RNTO Ta "specify rename-to file name"
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.It SITE Ta "non-standard commands (see next section)"
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.It SIZE Ta "return size of file"
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.It STAT Ta "return status of server"
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.It STOR Ta "store a file"
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.It STOU Ta "store a file with a unique name"
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.It STRU Ta "specify data transfer" Em structure
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.It SYST Ta "show operating system type of server system"
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.It TYPE Ta "specify data transfer" Em type
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.It USER Ta "specify user name"
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.It XCUP Ta "change to parent of current working directory (deprecated)"
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.It XCWD Ta "change working directory (deprecated)"
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.It XMKD Ta "make a directory (deprecated)"
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.It XPWD Ta "print the current working directory (deprecated)"
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.It XRMD Ta "remove a directory (deprecated)"
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.El
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.Pp
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The following non-standard or
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.Tn UNIX
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specific commands are supported
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by the
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SITE request.
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.Pp
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.Bl -column Request -offset indent
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.It Sy Request Ta Sy Description
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.It UMASK Ta change umask, e.g. ``SITE UMASK 002''
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.It IDLE Ta set idle-timer, e.g. ``SITE IDLE 60''
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.It CHMOD Ta change mode of a file, e.g. ``SITE CHMOD 755 filename''
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.It HELP Ta give help information.
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.El
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.Pp
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The remaining ftp requests specified in Internet RFC 959
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are
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recognized, but not implemented.
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MDTM and SIZE are not specified in RFC 959, but will appear in the
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next updated FTP RFC.
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.Pp
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The ftp server will abort an active file transfer only when the
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ABOR
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command is preceded by a Telnet "Interrupt Process" (IP)
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signal and a Telnet "Synch" signal in the command Telnet stream,
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as described in Internet RFC 959.
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If a
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STAT
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command is received during a data transfer, preceded by a Telnet IP
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and Synch, transfer status will be returned.
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.Pp
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.Nm Ftpd
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interprets file names according to the
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.Dq globbing
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conventions used by
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.Xr csh 1 .
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This allows users to utilize the metacharacters
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.Dq Li \&*?[]{}~ .
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.Pp
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.Nm Ftpd
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authenticates users according to five rules.
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.Pp
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.Bl -enum -offset indent
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.It
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The login name must be in the password data base,
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.Pa /etc/pwd.db ,
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and not have a null password.
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In this case a password must be provided by the client before any
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file operations may be performed.
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If the user has an S/Key key, the response from a successful USER
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command will include an S/Key challenge. The client may choose to respond
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with a PASS command giving either a standard password or an S/Key
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one-time password. The server will automatically determine which type of
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password it has been given and attempt to authenticate accordingly. See
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.Xr key 1
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for more information on S/Key authentication. S/Key is a Trademark of
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Bellcore.
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.It
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The login name must not appear in the file
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.Pa /etc/ftpusers .
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.It
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The user must have a standard shell returned by
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.Xr getusershell 3 .
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.It
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If the user name appears in the file
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.Pa /etc/ftpchroot
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the session's root will be changed to the user's login directory by
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.Xr chroot 2
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as for an
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.Dq anonymous
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or
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.Dq ftp
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account (see next item). However, the user must still supply a password.
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This feature is intended as a compromise between a fully anonymous account
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and a fully privileged account. The account should also be set up as for an
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anonymous account.
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.It
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If the user name is
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.Dq anonymous
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or
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.Dq ftp ,
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an
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anonymous ftp account must be present in the password
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file (user
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.Dq ftp ) .
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In this case the user is allowed
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to log in by specifying any password (by convention an email address for
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the user should be used as the password).
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When the
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.Fl S
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option is set, all transfers are logged as well.
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.El
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.Pp
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In the last case,
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.Nm ftpd
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takes special measures to restrict the client's access privileges.
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The server performs a
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.Xr chroot 2
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to the home directory of the
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.Dq ftp
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user.
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In order that system security is not breached, it is recommended
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that the
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.Dq ftp
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subtree be constructed with care, following these rules:
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.Bl -tag -width "~ftp/pub" -offset indent
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.It Pa ~ftp
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Make the home directory owned by
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.Dq root
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and unwritable by anyone.
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.It Pa ~ftp/bin
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Make this directory owned by
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.Dq root
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and unwritable by anyone (mode 555).
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The program
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.Xr ls 1
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must be present to support the list command.
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This program should be mode 111.
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.It Pa ~ftp/etc
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Make this directory owned by
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.Dq root
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and unwritable by anyone (mode 555).
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The files pwd.db (see
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.Xr passwd 5 )
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and
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.Xr group 5
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must be present for the
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.Xr ls
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command to be able to produce owner names rather than numbers.
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The password field in
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.Xr passwd
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is not used, and should not contain real passwords.
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The file
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.Pa ftpmotd ,
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if present, will be printed after a successful login.
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These files should be mode 444.
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.It Pa ~ftp/pub
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Make this directory mode 777 and owned by
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.Dq ftp .
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Guests
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can then place files which are to be accessible via the anonymous
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account in this directory.
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.El
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.Sh FILES
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.Bl -tag -width /etc/ftpwelcome -compact
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.It Pa /etc/ftpusers
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List of unwelcome/restricted users.
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.It Pa /etc/ftpchroot
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List of normal users who should be chroot'd.
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.It Pa /etc/ftpwelcome
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Welcome notice.
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.It Pa /etc/ftpmotd
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Welcome notice after login.
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.It Pa /etc/nologin
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Displayed and access refused.
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.It Pa /var/log/ftpd
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Log file for anonymous transfers.
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.El
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.Sh SEE ALSO
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.Xr ftp 1 ,
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.Xr key 1 ,
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.Xr getusershell 3 ,
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.Xr inetd 8 ,
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.Xr syslogd 8
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.Sh BUGS
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The server must run as the super-user
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to create sockets with privileged port numbers. It maintains
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an effective user id of the logged in user, reverting to
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the super-user only when binding addresses to sockets. The
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possible security holes have been extensively
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scrutinized, but are possibly incomplete.
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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 4.2 .
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