4.4BSD/usr/share/man/cat8/ftpd.0
FTPD(8) BSD System Manager's Manual FTPD(8)
NNAAMMEE
ffttppdd - Internet File Transfer Protocol server
SSYYNNOOPPSSIISS
ffttppdd [--ddll] [--TT _m_a_x_t_i_m_e_o_u_t] [--tt _t_i_m_e_o_u_t]
DDEESSCCRRIIPPTTIIOONN
FFttppdd 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).
Available options:
--dd Debugging information is written to the syslog using LOG_FTP.
--ll 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 argu-
ments are also logged.
--TT A client may also request a different timeout period; the maximum
period allowed may be set to _t_i_m_e_o_u_t seconds with the --TT option.
The default limit is 2 hours.
--tt The inactivity timeout period is set to _t_i_m_e_o_u_t seconds (the de-
fault is 15 minutes).
The file _/_e_t_c_/_n_o_l_o_g_i_n can be used to disable ftp access. If the file ex-
ists, ffttppdd displays it and exits. If the file _/_e_t_c_/_f_t_p_w_e_l_c_o_m_e exists,
ffttppdd prints it before issuing the ``ready'' message. If the file
_/_e_t_c_/_m_o_t_d exists, ffttppdd prints it after a successsful 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
HELP give help information
LIST give list files in a directory (``ls -lgA'')
MKD make a directory
MDTM show last modification time of file
MODE specify data transfer _m_o_d_e
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
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 _s_t_r_u_c_t_u_r_e
SYST show operating system type of server system
TYPE specify data transfer _t_y_p_e
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.
RReeqquueesstt DDeessccrriippttiioonn
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 CHMOD0 0CHMOD1
1CHMOD2
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 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.
FFttppdd interprets file names according to the ``globbing'' conventions used
by csh(1). This allows users to utilize the metacharacters ``*?[]{}~''.
FFttppdd authenticates users according to three rules.
1. The login name must be in the password data base, _/_e_t_c_/_p_a_s_s_w_d,
and not have a null password. In this case a password must be
provided by the client before any file operations may be per-
formed.
2. The login name must not appear in the file _/_e_t_c_/_f_t_p_u_s_e_r_s.
3. The user must have a standard shell returned by
getusershell(3).
4. 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, ffttppdd 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, follow-
ing these rules:
_~_f_t_p Make the home directory owned by ``root'' and unwritable
by anyone.
_~_f_t_p_/_b_i_n 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.
_~_f_t_p_/_e_t_c 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 _m_o_t_d, if present, will be printed after a sucessful
login. These files should be mode 444.
_~_f_t_p_/_p_u_b 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.
FFIILLEESS
/etc/ftpusers List of unwelcome/restricted users.
/etc/ftpwelcome Welcome notice.
/etc/motd Welcome notice after login.
/etc/nologin Displayed and access refused.
SSEEEE AALLSSOO
ftp(1), getusershell(3), syslogd(8)
BBUUGGSS
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 possi-
bly incomplete.
HHIISSTTOORRYY
The ffttppdd command appeared in 4.2BSD.
4.2 Berkeley Distribution June 4, 1993 3