10.2;ftpd (ftp daemon), revision 2.0, 89/03/31
ftpd (ftp daemon) -DARPA Internet File Transfer Protocol server
usage: ftpd [ -d ] [-l ] [ -t timeout ]
DESCRIPTION
ftpd is the DARPA 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.
OPTIONS
-d Write debugging information to the syslog.
-l Log each ftp session in the syslog.
-ttimeout Set the inactivity timeout period to timeout. Without this
option, the ftp server will timeout an inactive session after
15 minutes.
FTP REQUESTS
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 List files in a directory ("ls -lg")
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 filename
RNTO Specify rename-to filename
STOR Store a file
STOU Store a file with a unique name
STRU Specify data transfer structure
TYPE Specify data transfer type
USER Specify username
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 Telnet stream, as described in
Internet RFC 959.
ftpd interprets filenames according to the "globbing" conventions used by
csh(1). This allows users to utilize the metacharacters "*?[]{}~".
ftpd authenticates users according to four rules.
1) The username 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 username must not appear in the file /etc/ftpusers.
3) The user must have a standard shell.
4) If the username 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 command to the home
directory of the "ftp" user. In order that system security is not
breached, we recommend 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 unwritable by
anyone. The program ls(1) must be present to support the list
commands. This program should have mode 111.
~ftp/etc Make this directory owned by the super-user and unwritable by
anyone. The files passwd and group must be present for the ls
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 accessible via the anonymous
account in this directory.
BUGS
Because Domain/OS does not support the chroot command, ftpd does not
support an anonymous ftp account.
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.
ftpd does not support the options: structured page, mode block, or mode
compressed.
SEE ALSO
ftp, syslogd,
Configuring and Managing TCP/IP.