NAME

ftpd — Internet File Transfer Protocol server

SYNOPSIS

ftpd [option ...]

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” service specification; see services(5).

OPTIONS

-4, --ipv4

Restrict daemon to listen to IPv4 addresses only.

-6, --ipv6

Restrict daemon to listen to IPv6 addresses only.

-d, --debug

Debugging information is written to the syslog using LOG_FTP.

-l, --logging

Each successful and failed ftp(1) 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 arguments are also logged.

-A, --anonymous-only

Only anonymous login is allowed.

-D, --daemon

ftpd enters daemon-mode. That allows ftpd to be run without inetd.

-q, --no-version

Quiet mode. No information about the version of the ftpd is given to the client.

-T, --max-timeout timeout

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

-t, --timeout timeout

The inactivity timeout period is set to timeout seconds (the default is 15 minutes).

-p, --pidfile pidfile

Change default location of pidfile.

-a, --auth auth

Give anonymous another login-name (anonymous and ftpd will still work). It can be one of

default: Use passwd authentication.
pam: Use PAM service 'ftp'.

--non-rfc2577

Neglect RFC 2577 by giving information on missing users.

-u, --umask value

Set default umask to value.

-?, --help

Display a help list.

--usage

Display a short usage message.

-V, --version

Display program version.

OPERATION

The file /etc/nologin can be used to disable ftp access. If the file exists, ftpd displays it and exits. If the file /etc/ftpwelcome exists, ftpd prints it before issuing the “ready” message. If the file /etc/motd exists, ftpd prints it after a successful login.

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 (ignored)
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	extended data connection port, RFC 2428
EPSV	extended passive transfer request, RFC 2428
FEAT	display command extensions
HELP	give help information
LIST	give list files in a directory (“`ls -lgA`”)
LPRT	long data connection port, RFC 1639
LPSV	long passive transfer request, RFC 1639
MKD	make a directory
MDTM	show last modification time of file
MODE	specify data transfer mode
NLST	give name list of files in directory
NOOP	do nothing
OPTS	option settings
PASS	specify password
PASV	prepare for server-to-server transfer
PORT	specify data connection port
PWD	print the current working directory
QUIT	terminate session
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
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
XCUP	change to parent of current working directory (deprecated)
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
UMASK	change umask, e.g. ``SITE UMASK 002''
IDLE	set idle-timer, e.g. ``SITE IDLE 60''
CHMOD	change mode of a file, e.g. ``SITE CHMOD 755 filename''
HELP	give help information.

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 command 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 according to three rules.

The login name must be in the password data base, /etc/passwd, and not have a null password. In this case a password must be provided by the client before any file operations may be performed.
The login name must not appear in the file /etc/ftpusers.
The user must have a standard shell returned by getusershell(3).
If the user name is “anonymous” or “ftp”, an anonymous ftp account 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).

In the last case, 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.
~ftp/bin: Make this directory owned by “root” and unwritable by anyone (mode 555). The program ls(1) must be present to support the list command. This program should be mode 111.
~ftp/etc: Make this directory owned by “root” and unwritable by anyone (mode 555). The files passwd(5) and group(5) must be present for the ls command to be able to produce owner names rather than numbers. The password field in passwd 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 777 and owned by “ftp”. Guests can then place files which are to be accessible via the anonymous account in this directory.

FILES

/etc/ftpusers: List of unwelcome/restricted users.
/etc/ftpwelcome: Welcome notice.
/etc/motd: Welcome notice after login.
/etc/nologin: Displayed and access refused.

BUGS

The server must run as the super-user to create sockets with privileged port numbers. It maintains an effective user id of the logged in user, reverting to the super-user only when binding addresses to sockets. The possible security holes have been extensively scrutinized, but are possibly incomplete.

HISTORY

The ftpd command appeared in 4.2BSD.