4.3BSD-Tahoe/usr/man/cat8/ftpd.0
FTPD(8C) UNIX Programmer's Manual FTPD(8C)
NNAAMMEE
ftpd - DARPA Internet File Transfer Protocol server
SSYYNNOOPPSSIISS
//eettcc//ffttppdd [ --dd ] [ --ll ] [ --tttimeout ]
DDEESSCCRRIIPPTTIIOONN
_F_t_p_d is the DARPA Internet File Transfer Prototocol server
process. The server uses the TCP protocol and listens at
the port specified in the ``ftp'' service specification; see
_s_e_r_v_i_c_e_s(5).
If the --dd option is specified, debugging information is
written to the syslog.
If the --ll option is specified, each ftp session is logged in
the syslog.
The ftp server will timeout an inactive session after 15
minutes. If the --tt option is specified, the inactivity
timeout period will be set to _t_i_m_e_o_u_t.
The ftp server currently supports the following ftp
requests; case is not distinguished.
RReeqquueesstt DDeessccrriippttiioonn
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 -lg'')
MKD make a directory
MODE specify data transfer _m_o_d_e
NLST give name list of files in directory (``ls'')
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
RETR retrieve a file
RMD remove a directory
RNFR specify rename-from file name
RNTO specify rename-to file name
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
TYPE specify data transfer _t_y_p_e
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FTPD(8C) UNIX Programmer's Manual FTPD(8C)
USER specify user name
XCUP change to parent of current working directory
XCWD change working directory
XMKD make a directory
XPWD print the current working directory
XRMD remove a directory
The remaining ftp requests specified in Internet RFC 959 are
recognized, but not implemented.
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 Tel-
net stream, as described in Internet RFC 959.
_F_t_p_d interprets file names according to the ``globbing''
conventions used by _c_s_h(1). This allows users to utilize
the metacharacters ``*?[]{}~''.
_F_t_p_d authenticates users according to three rules.
1) The user 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 performed.
2) The user 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
_g_e_t_u_s_e_r_s_h_e_l_l(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
this is given as the client host's name).
In the last case, _f_t_p_d takes special measures to restrict
the client's access privileges. The server performs a
_c_h_r_o_o_t(2) command to the home directory of the ``ftp'' user.
In order that system security is not breached, it is recom-
mended that the ``ftp'' subtree be constructed with care;
the following rules are recommended.
~ftp)
Make the home directory owned by ``ftp'' and unwritable
by anyone.
~ftp/bin)
Make this directory owned by the super-user and unwrit-
able by anyone. The program _l_s(1) must be present to
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FTPD(8C) UNIX Programmer's Manual FTPD(8C)
support the list commands. This program should have
mode 111.
~ftp/etc)
Make this directory owned by the super-user and unwrit-
able by anyone. The files _p_a_s_s_w_d(5) and _g_r_o_u_p(5) must
be present for the _l_s command to work properly. These
files should be mode 444.
~ftp/pub)
Make this directory mode 777 and owned by ``ftp''.
Users should then place files which are to be accessi-
ble via the anonymous account in this directory.
SSEEEE AALLSSOO
ftp(1C), getusershell(3), syslogd(8)
BBUUGGSS
The anonymous account is inherently dangerous and should
avoided when possible.
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 incom-
plete.
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