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FTPD(8)			  BSD System Manager's Manual		       FTPD(8)

     ftpd -- Internet File Transfer Protocol server

     ftpd [-46ADdlMnPSUW] [-m minuid] [-T maxtimeout] [-t timeout] [-u mask]

     ftpd is the Internet File Transfer	Protocol server	process.  The server
     uses the TCP protocol and listens at the port specified in	the "ftp" ser-
     vice specification; see services(5).

     The options are as	follows:

     -4	     When -D is	specified, forces ftpd to use IPv4 addresses only.

     -6	     When -D is	specified, forces ftpd to use IPv6 addresses only.

     -A	     Permit only anonymous FTP connections (unless the -n option is
	     specified), accounts listed in /etc/ftpchroot or users in a login
	     class with	the "ftp-chroot" variable set (see below).  Other con-
	     nection attempts are refused.

     -D	     With this option set, ftpd	will detach and	become a daemon, ac-
	     cepting connections on the	FTP port and forking child processes
	     to	handle them.  This has lower overhead than starting ftpd from
	     inetd(8) and is thus useful on busy servers to reduce load.

     -d	     Debugging information is written to the syslog using LOG_FTP.

     -l	     Each successful and failed	FTP session is logged using syslog
	     with a facility of	LOG_FTP.  If this option is specified twice,
	     the retrieve (get), store (put), append, delete, make directory,
	     remove directory and rename operations and	their filename argu-
	     ments are also logged.

     -M	     Enables multihomed	mode.  Instead of simply using ~ftp for	anony-
	     mous transfers, a directory matching the fully qualified name of
	     the IP number the client connected	to, and	located	inside ~ftp,
	     is	used instead.

     -m	minuid
	     Disallow login to user accounts with a UID	below minuid.  The de-
	     fault is 1000, to prevent access to administrative	and daemon ac-
	     counts.  Anonymous	access is allowed even if the UID of the FTP
	     user is smaller than minuid.

     -n	     Do	not permit anonymous FTP logins.  Normally they	are permitted.

     -P	     Permit illegal port numbers or addresses for PORT command initi-
	     ated connects.  By	default	ftpd violates the RFC and thus con-
	     strains the PORT command to non-reserved ports and	requires it
	     use the same source address as the	connection came	from.  This
	     prevents the "FTP bounce attack" against services on both the lo-
	     cal machine and other local machines.

     -S	     With this option set, ftpd	logs all anonymous downloads to	the
	     file /var/log/ftpd	when this file exists.

     -T	maxtimeout
	     A client may also request a different timeout period; the maximum
	     period allowed may	be set to maxtimeout seconds with the -T op-
	     tion.  The	default	limit is 2 hours.

     -t	timeout
	     The inactivity timeout period is set to timeout seconds (the de-
	     fault is 15 minutes).

     -U	     Each concurrent FTP session is logged to the file /var/run/utmp,
	     making them visible to commands such as who(1).  -U and -W	are
	     mutually exclusive.

     -u	mask
	     Force the umask to	mask, instead of the default specified in
	     /etc/login.conf (usually 022).  Also disallows chmod.

     -W	     Do	not save login records to /var/log/wtmp.  -W and -U are	mutu-
	     ally exclusive.

     The file /etc/nologin can be used to disable FTP access.  If the file ex-
     ists, ftpd	displays it and	exits.	Note: this method will disable all
     non-root logins; see login(1) for further details.	 If the	file
     /etc/ftpwelcome exists, ftpd prints it before issuing the "ready" mes-
     sage.  If the welcome file	exists (/etc/motd by default), ftpd prints it
     after a successful	login.	If the file .message exists in a directory,
     ftpd prints it when that directory	is entered.

     The FTP server currently supports the following FTP requests.  The	case
     of	the requests is	ignored.

	   Request    Description
	   ABOR	      abort previous command
	   ACCT	      specify account (not implemented)
	   ALLO	      allocate storage (vacuously)
	   APPE	      append to	a file
	   CDUP	      change to	parent of current working directory
	   CWD	      change working directory
	   DELE	      delete a file
	   EPRT	      specify data connection port
	   EPSV	      prepare for server-to-server transfer
	   HELP	      give help	information
	   LIST	      give list	of files in a directory	(ls -lgA)
	   LPRT	      specify data connection port
	   LPSV	      prepare for server-to-server transfer
	   MDTM	      show last	modification time of file
	   MKD	      make a directory
	   MODE	      specify data transfer mode
	   NLST	      give name	list of	files in directory
	   NOOP	      do nothing
	   PASS	      specify password
	   PASV	      prepare for server-to-server transfer
	   PORT	      specify data connection port
	   PWD	      print the	current	working	directory
	   QUIT	      terminate	session
	   REIN	      reinitialize (not	implemented)
	   REST	      restart incomplete transfer
	   RETR	      retrieve a file
	   RMD	      remove a directory
	   RNFR	      specify rename-from file name
	   RNTO	      specify rename-to	file name
	   SITE	      non-standard commands (see next section)
	   SIZE	      return size of file
	   SMNT	      structure	mount (not implemented)
	   STAT	      return status of server
	   STOR	      store a file
	   STOU	      store a file with	a unique name
	   STRU	      specify data transfer structure
	   SYST	      show operating system type of server system
	   TYPE	      specify data transfer type
	   USER	      specify user name; not valid after login
	   XCUP	      change to	parent of current working directory (deprec.)
	   XCWD	      change working directory (deprecated)
	   XMKD	      make a directory (deprecated)
	   XPWD	      print the	current	working	directory (deprecated)
	   XRMD	      remove a directory (deprecated)

     The following non-standard	or UNIX	specific commands are supported	by the
     SITE request:

	   Request    Description
	   CHMOD      change mode of a file, e.g., SITE	CHMOD 755 filename
	   HELP	      give help	information
	   IDLE	      set idle-timer, e.g., SITE IDLE 60
	   UMASK      change umask, e.g., SITE UMASK 002

     The remaining FTP requests	specified in Internet RFC 959 are recognized,
     but not implemented.  MDTM	and SIZE are specified in RFC 3659.

     The FTP server will abort an active file transfer only when the ABOR com-
     mand is preceded by a Telnet "Interrupt Process" (IP) signal and a	Telnet
     "Synch" signal in the command Telnet stream, as described in Internet RFC
     959.  If a	STAT command is	received during	a data transfer, preceded by a
     Telnet IP and Synch, transfer status will be returned.

     ftpd interprets file names	according to the "globbing" conventions	used
     by	csh(1).	 This allows users to utilize the metacharacters "*?[]{}~".

     ftpd authenticates	users by using the service and type of ftp, as defined
     in	the /etc/login.conf file (see login.conf(5)).  An authentication style
     may be specified by appending with	a colon	(`:') following	the authenti-
     cation style, i.e.	"joe:skey".  The allowed authentication	styles for
     ftpd may be explicitly specified by the "auth-ftp"	entry in

     ftpd authenticates	users according	to the following rules.

	   1.	The login name must be in the password database	and not	have a
		null password.	In this	case a password	must be	provided by
		the client before any file operations may be performed.

	   2.	The login name must not	appear in the file /etc/ftpusers.

	   3.	The user account must have a UID not less than minuid.

	   4.	The user must have a standard shell as described by shells(5).

	   5.	If the user name appears in the	file /etc/ftpchroot, which is
		a text file containing one user	name per line, the session's
		root will be changed to	the user's login directory by
		chroot(2) as for an "anonymous"	or "ftp" account (see next
		item).	However, the user must still supply a password.	 This
		feature	is intended as a compromise between a fully anonymous
		account	and a fully privileged account.	 The account should
		also be	set up as for an anonymous account.

	   6.	If the user name is "anonymous"	or "ftp", an anonymous FTP ac-
		count must be present in the password file (user "ftp").  In
		this case the user is allowed to log in	by specifying any
		password (by convention	an email address for the user should
		be used	as the password).

     Once a user is authenticated the user must	be approved by any approval
     script defined (see login.conf(5)).  If a valid approval script (by ei-
     ther :approve=...:	or :approve-ftp=...: for the user's class) is defined
     then it is	run and	must exit with a 0 (success) status.  When ftpd	is
     running under the -D flag (and debugging is not turned on)	then the ap-
     proval script will	be called with at least	the following variables	speci-
     fied via the -v option (see login.conf(5))	to the approve script:

	   Variable    Description
	   FTPD_HOST   The server's (virtual) hostname

     For example (the line is broken to	fit the	page):

	   /usr/libexec/auth/approve_ftpd -v \
		   username class service

     When the user logs	in to the anonymous FTP	account, ftpd takes special
     measures to restrict the client's access privileges.  The server performs
     a chroot(2) to the	home directory of the "ftp" user.  In order that sys-
     tem security is not breached, it is recommended that the "ftp" subtree be
     constructed with care, following these rules:

	   ~ftp	     Make the home directory owned by "root" and unwritable by
		     anyone (mode 555).

	   ~ftp/bin  Make this directory owned by "root" and unwritable	by
		     anyone (mode 511).	 This directory	is optional unless you
		     have commands you wish the	anonymous FTP user to be able
		     to	run (the ls(1) command exists as a built-in).  Any
		     programs in this directory	should be mode 111 (executable

	   ~ftp/etc  Make this directory owned by "root" and unwritable	by
		     anyone (mode 511).	 The files pwd.db (see pwd_mkdb(8))
		     and group(5) must be present for the ls(1)	command	to be
		     able to produce owner names rather	than numbers.  The
		     password field in pwd.db is not used, and should not con-
		     tain real passwords.  The file motd, if present, will be
		     printed after a successful	login.	These files should be
		     mode 444.

	   ~ftp/pub  Make this directory mode 555 and owned by "root".	This
		     is	traditionally where publicly accessible	files are
		     stored for	download.

     If	logging	to the /var/log/ftpd file is enabled, information will be
     written in	the following format:

	   time		   The time and	date of	the download, in ctime(3) for-
	   elapsed time	   The elapsed time, in	seconds.
	   remote host	   The remote host (or IP number).
	   bytes	   The number of bytes transferred.
	   path		   The full path (relative to the FTP chroot space) of
			   the file transferred.
	   type		   The type of transfer; either	`a' for	ASCII or `b'
			   for binary.
	   unused	   Unused field	containing a `*', for compatibility.
	   unused	   Unused field	containing an `o', for compatibility.
	   user	type	   The type of user; either `a'	for anonymous or `r'
			   for a real user (should always be anonymous).
	   name		   Either a system login name or the value given for
			   "email address" if an anonymous user.
	   service name	   The network service name (always ftp).
	   unused	   Unused field	containing a `0', for compatibility.
	   real	name	   The system login name if the	connection is not
			   anonymous, or a `*' if it is.

     Although fields exist for logging information on real users, this file is
     only used for anonymous downloads.	 Unused	fields exist only for compati-
     bility with other ftpd implementations.

     The ftpd daemon uses the following	FTP-specific parameters:

     auth-ftp	 The list of authentication types available to this class.
		 See login.conf(5).

     ftp-chroot	 A boolean value.  If set, users in this class will be auto-
		 matically chrooted to the user's login	directory.

     ftp-dir	 A path	to a directory.	 This value overrides the login	direc-
		 tory for users	in this	class.	A leading tilde	(`~') in
		 ftp-dir will be expanded to the user's	home directory based
		 on the	contents of the	password database.

     welcome	 The path of the file containing the welcome message.  If this
		 variable is not set, /etc/motd	is used.

     For passive mode data connections,	ftpd will listen to a random high TCP
     port.  The	interval of ports used are configurable	using sysctl(8)	vari-
     ables net.inet.ip.porthifirst and net.inet.ip.porthilast.

     /etc/ftpchroot   list of normal users who should be chrooted
     /etc/ftpusers    list of unwelcome/restricted users
     /etc/ftpwelcome  welcome notice
     /etc/login.conf  authentication styles
     /etc/motd	      printed after a successful login
     /etc/nologin     displayed	and access refused
     /var/log/ftpd    log file for anonymous downloads
     /var/log/wtmp    login account records
     /var/run/utmp    list of users on the system

     ftp(1), login(1), skey(1),	who(1),	chroot(2), ctime(3), group(5),
     login.conf(5), motd(5), services(5), shells(5), ftp-proxy(8), inetd(8),
     pwd_mkdb(8), sysctl(8), syslogd(8)

     J.	Postel and J. Reynolds,	FILE TRANSFER PROTOCOL (FTP), RFC 959, October

     P.	Hethmon, Extensions to FTP, RFC	3659, March 2007.

     The ftpd command appeared in 4.2BSD.

BSD			       October 25, 2015				   BSD


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