.TH FTPD 8C "4 March 1983"
ftpd \- DARPA Internet File Transfer Protocol server
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
option is specified when the server is started up,
each socket created will have debugging turned
on (SO_DEBUG). With debugging enabled, the system
will trace all TCP packets sent and received on a
may then be used to interpret the packet traces.
The ftp server currently supports the following ftp
requests; case is not distinguished.
\fBRequest Description\fP
ACCT specify account (ignored)
ALLO allocate storage (vacuously)
CWD change working directory
HELP give help information
LIST give list files in a directory (``ls -lg'')
MODE specify data transfer \fImode\fP
NLST give name list of files in directory (``ls'')
PORT specify data connection port
RNFR specify rename-from file name
RNTO specify rename-to file name
STRU specify data transfer \fIstructure\fP
TYPE specify data transfer \fItype\fP
XCUP change to parent of current working directory
XCWD change working directory
XPWD print the current working directory
The remaining ftp requests specified in Internet RFC 765 are
recognized, but not implemented.
interprets file names according to the ``globbing''
This allows users to utilize the metacharacters ``*?[]{}~''.
authenticates users according to three rules.
The user name must be in the password data base,
and not have a null password. In this case a password
must be provided by the client before any file operations
The user name must not appear in the file
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).
takes special measures to restrict the client's access privileges.
command to the home directory of the ``ftp'' user and interprets
path names to insure references are maintained within the subtree.
In order that system security is not breached, it is recommended
that the ``ftp'' subtree be constructed with care; the following
Make the home directory owned by ``ftp'' and unwritable by anyone.
Make this directory owned by the super-user and unwritable by
must be present to support the list commands. These
programs should have mode 111.
Make this directory owned by the super-user and unwritable by
command to work properly. These files should be mode 444.
Make this directory mode 777 and owned by ``ftp''. Users
should then place files which are to be accessible via the
anonymous account in this directory.
There is no support for aborting commands.
The anonymous account is inherently dangerous and should
The server must run with real user id of 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.