474 lines
13 KiB
Groff
474 lines
13 KiB
Groff
.\" $NetBSD: ftpd.8,v 1.7 1995/04/11 02:44:53 cgd Exp $
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.\"
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.\" 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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.\"
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.Dd April 19, 1997
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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 a Ar authmode
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.Op Fl dilv
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.Op Fl g Ar umask
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.Op Fl p Ar port
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.Op Fl T Ar maxtimeout
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.Op Fl t Ar timeout
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.Op Fl u Ar default umask
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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 a
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Select the level of authentication required. Kerberised login can not
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be turned off. The default is to only allow kerberised login. Other
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possibilities can be turned on by giving a string of comma separated
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flags as argument to
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.Fl a .
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Recognised flags are:
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.Bl -tag -width plain
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.It Ar plain
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Allow logging in with plaintext password. The password can be a(n) OTP
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or an ordinary password.
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.It Ar otp
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Same as
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.Ar plain ,
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but only OTP is allowed.
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.It Ar ftp
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Allow anonymous login.
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.El
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The following combination modes exists for backwards compatibility:
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.Bl -tag -width plain
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.It Ar none
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Same as
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.Ar plain,ftp .
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.It Ar safe
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Same as
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.Ar ftp .
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.It Ar user
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Ignored.
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.El
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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 g
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Anonymous users will get a umask of
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.Ar umask .
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.It Fl i
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Open a socket and wait for a connection. This is mainly used for
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debugging when ftpd isn't started by inetd.
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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.
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.It Fl p
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Use
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.Ar port
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(a service name or number) instead of the default
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.Ar ftp/tcp .
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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 u
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Set the initial umask to something else than the default 027.
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.It Fl v
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Verbose mode.
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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/motd
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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 commands are specified by RFC2228.
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.Bl -column Request -offset indent
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.It AUTH Ta "authentication/security mechanism"
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.It ADAT Ta "authentication/security data"
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.It PROT Ta "data channel protection level"
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.It PBSZ Ta "protection buffer size"
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.It MIC Ta "integrity protected command"
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.It CONF Ta "confidentiality protected command"
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.It ENC Ta "privacy protected command"
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.It CCC Ta "clear command channel"
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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 UMASK Ta change umask, (e.g.
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.Ic "SITE UMASK 002" )
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.It IDLE Ta set idle-timer, (e.g.
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.Ic "SITE IDLE 60" )
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.It CHMOD Ta change mode of a file (e.g.
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.Ic "SITE CHMOD 755 filename" )
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.It FIND Ta quickly find a specific file with GNU
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.Xr locate 1 .
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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 following Kerberos related site commands are understood.
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.Bl -column Request -offset indent
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.It KAUTH Ta obtain remote tickets.
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.It KLIST Ta show remote tickets
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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 these rules.
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.Pp
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.Bl -enum -offset indent
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.It
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If Kerberos authentication is used, the user must pass valid tickets
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and the principal must be allowed to login as the remote user.
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.It
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The login name must be in the password data base, and not have a null
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password (if kerberos is used the password field is not checked). In
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this case a password must be provided by the client before any file
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operations may be performed. If the user has an OTP key, the response
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from a successful USER command will include an OTP challenge. The
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client may choose to respond with a PASS command giving either a
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standard password or an OTP one-time password. The server will
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automatically determine which type of password it has been given and
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attempt to authenticate accordingly. See
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.Xr otp 1
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for more information on OTP authentication.
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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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.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, consider following these guidelines
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for anonymous ftp.
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In general all files should be owned by
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.Dq root ,
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and have non-write permissions (644 or 755 depending on the kind of
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file). No files should be owned or writable by
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.Dq ftp
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(possibly with exception for the
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.Pa ~ftp/incoming ,
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as specified below).
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.Bl -tag -width "~ftp/pub" -offset indent
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.It Pa ~ftp
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The
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.Dq ftp
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homedirectory should be owned by root.
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.It Pa ~ftp/bin
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The directory for external programs (such as
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.Xr ls 1 ) .
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These programs must either be statically linked, or you must setup an
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environment for dynamic linking when running chrooted.
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These programs will be used if present:
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.Bl -tag -width "locate" -offset indent
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.It ls
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Used when listing files.
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.It compress
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When retrieving a filename that ends in
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.Pa .Z ,
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and that file isn't present,
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.Nm
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will try to find the filename without
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.Pa .Z
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and compress it on the fly.
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.It gzip
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Same as compress, just with files ending in
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.Pa .gz .
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.It gtar
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Enables retrieval of whole directories as files ending in
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.Pa .tar .
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Can also be combined with compression. You must use GNU Tar (or some
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other that supports the
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.Fl z
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and
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.Fl Z
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flags).
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.It locate
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Will enable ``fast find'' with the
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.Ic SITE FIND
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command. You must also create a
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.Pa locatedb
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file in
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.Pa ~ftp/etc .
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.El
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.It Pa ~ftp/etc
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If you put copies of the
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.Xr passwd 5
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and
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.Xr group 5
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files here, ls will be able to produce owner names rather than
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numbers. Remember to remove any passwords from these files.
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The file
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.Pa motd ,
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if present, will be printed after a successful login.
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.It Pa ~ftp/dev
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Put a copy of
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.Xr /dev/null 7
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here.
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.It Pa ~ftp/pub
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Traditional place to put whatever you want to make public.
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.El
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If you want guests to be able to upload files, create a
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.Pa ~ftp/incoming
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directory owned by
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.Dq root ,
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and group
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.Dq ftp
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with mode 730 (make sure
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.Dq ftp
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is member of group
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.Dq ftp ) .
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The following restrictions apply to anonymous users:
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.Bl -bullet
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.It
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Directories created will have mode 700.
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.It
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Uploaded files will be created with an umask of 777, if not changed
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with the
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.Fl g
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option.
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.It
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These command are not accessible:
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.Ic DELE , RMD , RNTO , RNFR ,
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.Ic SITE UMASK ,
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and
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.Ic SITE CHMOD .
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.It
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Filenames must start with an alpha-numeric character, and consist of
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alpha-numeric characters or any of the following:
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.Li \&+
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(plus),
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.Li \&-
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(minus),
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.Li \&=
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(equal),
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.Li \&_
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(underscore),
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.Li \&.
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(period), and
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.Li \&,
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(comma).
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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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Access list for 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/motd
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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 ~/.klogin
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Login access for Kerberos.
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.El
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.Sh SEE ALSO
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.Xr ftp 1 ,
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.Xr otp 1 ,
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.Xr getusershell 3 ,
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.Xr ftpusers 5 ,
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.Xr syslogd 8 ,
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.Sh STANDARDS
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.Bl -tag -compact -width "RFC 1938"
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.It Cm RFC 959
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FTP PROTOCOL SPECIFICATION
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.It Cm RFC 1938
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OTP Specification
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.It Cm RFC 2228
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FTP Security Extensions.
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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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