ftpd, in.ftpd - TCP/IP Internet File Transfer Protocol server
/usr/etc/in.ftpd [ -dl ] [ -ttimeout ] host.socket
This program is available with the Networking software installation
option. Refer to for information on how to install optional software.
ftpd is the TCP/IP Internet File Transfer Protocol (FTP) server
process. The server is invoked by the Internet daemon inetd(8C) each
time a connection to the FTP service (see services(5)) is made, with
the connection available as descriptor 0 and the host and socket the
connection originated from (in hex and decimal respectively) as argu-
Inactive connections are timed out after 60 seconds.
If the -d option is specified, debugging information is logged to the
system log daemon, syslogd(8).
If the -l option is specified, each FTP session is logged to syslogd.
The FTP server will timeout an inactive session after 15 minutes. If
the -t option is specified, the inactivity timeout period will be set
The FTP server currently supports the following FTP requests; case is
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 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 RFC 959 are recognized, but not
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 RFC
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.
o 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 per-
o If the file /etc/ftpusers exists, the user name must not appear
in that file.
o The user must have a standard shell returned by getusershell(3).
o 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 pass-
word (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 recommended that the "ftp" subtree be constructed with
care; the following rules are recommended.
~ftp Make the home directory owned by "ftp" and unwritable by any-
Make this directory owned by the super-user and unwritable by
anyone. The program ls(1V) must be present to support the list
commands. This program should have mode 111. Since the
default /bin/ls command is linked with a shared library, so you
need to set up the files for dynamic linking as well.
the runtime loader must be present and executable.
used by the runtime loader, create this with the command "mknod
zero c 3 12".
should be a copy of the latest version of the shared C library.
Make this directory owned by the super-user and unwritable by
anyone. The files passwd(5) and group(5) must be present for
the ls command to work properly. These files should be mode
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.
ftpd logs various errors to the system log daemon, syslogd, with a
facility code of daemon. The messages are listed here, grouped by
getpeername failed: reason
A getpeername(2) call failed.
getsockname failed: reason
A getsockname(2) call failed.
signal failed: reason
A signal (3V) (see signal(3V)) call failed.
setsockopt failed: reason
A setsockopt call (see getsockopt(2)) failed.
ioctl failed: reason
A ioctl(2) call failed.
ftpd did not have write permission on the directory directory in
which a file was to be created by the STOU command.
These messages are logged only if the -l flag is specified.
FTPD: connection from host at time
A connection was made to ftpd from the host host at the date and
FTPD: User user timed out after timeout seconds at time
The user user was logged out because they hadn't entered any
commands after timeout seconds; the logout occurred at the date
and time time.
These messages are logged only if the -d flag is specified.
1FTPD: command: command
A command line containing command was read from the FTP client.
The FTP client dropped the connection.
A reply was sent to the FTP client with the reply code reply-
code. The next message logged will include the message associ-
ated with the reply. If a - follows the reply code, the reply
is continued on later lines.
csh(1), ftp(1C), ls(1V), chroot(2) getpeername(2), getsockname(2), get-
sockopt(2), ioctl(2), getusershell(3), ftpusers(5), group(5),
passwd(5), services(5), inetd(8C), syslogd(8)
Postel, Jon, and Joyce Reynolds, File Transfer Protocol (FTP), RFC 959,
Network Information Center, SRI International, Menlo Park, Calif.,
The anonymous account is inherently dangerous and should be avoided
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
18 December 1989 FTPD(8C)