ftpd man page on MirBSD

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

NAME
     ftpd - Internet File Transfer Protocol server

SYNOPSIS
     ftpd [-46ADdflMnPSU] [-T maxtimeout] [-t timeout] [-u mask]

DESCRIPTION
     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.

     -f	     Disables the DELE and RMD commands for anonymous users.

     -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
	     anonymous transfers, a directory matching the fully qualified
	     name of the IP number the client connected to, and located inside
	     ~ftp, is used instead.

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

     -P	     Permit illegal port numbers or addresses for PORT command ini-
	     tiated 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 mask
	     Force the umask to mask, instead of the default specified in
	     /etc/login.conf (usually 022). Also disallows chmod.

     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 not specified in RFC 959, but will
     appear in the next updated FTP RFC.

     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 /etc/login.conf.

     ftpd authenticates users according to five 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 must have a standard shell as described by shells(5).

	   4.	If the user name appears in the file /etc/ftpchroot, 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.

	   5.	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 either
     :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 approval
     script will be called with at least the following variables specified 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 FTPD_HOST=ftp.mycompany.com \
		   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 system
     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 pro-
		     grams in this directory should be mode 111 (executable
		     only).

	   ~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 contain 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-
			   mat.
	   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.
	   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.

LOGIN.CONF VARIABLES
     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 automat-
		 ically 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.

PORT ALLOCATION
     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.

FILES
     /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/run/ftpd.pid	process ID if running in daemon mode
     /var/run/utmp	list of users on the system

SEE ALSO
     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)

HISTORY
     The ftpd command appeared in 4.2BSD. As of MirOS #8, there is an option
     to prevent anonymous users from deleting.

BUGS
     You ought to not be using the file transfer protocol at all; this daemon
     is only provided for compatibility reasons. A suitable alternative is
     scp(1), as well as sftp(1); you might use httpd(8) for simply sharing
     files, or NFS or CIFS/samba for discs.

MirOS BSD #10-current		June 18, 1996				     4
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