NAME
ftpd, in.ftpd, setup.anonftp - DARPA Internet File Transfer
Protocol server
SYNOPSIS
ftp stream tcp nowait root /usr/sbin/in.ftpd in.ftpd
tcpd ftp /usr/sbin/in.ftpd
DESCRIPTION
Ftpd 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
services(5).
The ftp server currently supports the following ftp
requests; case is not distinguished.
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 -lA'')
MKD make a directory
MODE specify data transfer mode
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 structure
TYPE specify data transfer type
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.
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.
1) The user 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.
2) The user name must not appear in the file
/etc/ftpusers.
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
this is given as the client host's name).
In the last case, ftpd takes special measures to restrict
the client's access privileges. The server performs a
chroot(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 ls(1) must be present to
support the list commands. This program should have
mode 111.
~ftp/etc)
This directory could be created, and could have
passwd(5) and group(5) databases in it so that ls can
show file ownership, but outsiders will grab your pass-
word file and misuse it to spam you. So don't bother.
~ftp/pub)
Make this directory mode 755 and owned by the super-
user. Create directories in it owned by users if those
users want to manage an anonymous ftp directory.
~ftp/pub/incoming)
Optionally create this directory for anonymous uploads.
Make it mode 777. The FTP daemon will create files
with mode 266, so remote users can write a file, but
only local users can do something with it.
The script setup.anonftp can be used to create or check an
anonymous FTP tree.
SEE ALSO
ftp(1).
BUGS
The anonymous account is inherently dangerous and should
avoided when possible.