ftpd(8)
FTPD(8) MAINTENANCE COMMANDS FTPD(8)
NAME
ftpd - Internet File Transfer Protocol server
SYNOPSIS
ftpd [ -d ] [ -v ] [ -l ] [ -t timeout ] [ -T maxtimeout ] [
-a ] [ -A ] [ -L ] [ -i ] [ -I ] [ -o ] [ -p ctrlport ] [ -P
dataport ] [ -q ] [ -Q ] [ -r rootdir ] [ -s ] [ -S ] [ -u
umask ] [ -V ] [ -w ] [ -W ] [ -X ]
DESCRIPTION
Ftpd is the Internet File Transfer Protocol server process.
The server uses the TCP protocol and listens at the port
specified in the ``ftp'' service specification; see ser-
vices(5).
The -V option causes the program to display copyright and
version information, then terminate.
If the -d or -v option is specified, debugging information
is written to the syslog.
If the -l option is specified, each ftp session is logged in
the syslog.
The ftp server will timeout an inactive session after 15
minutes. If the -t option is specified, the inactivity
timeout period will be set to timeout seconds. A client may
also request a different timeout period; the maximum period
allowed may be set to timeout seconds with the -T option.
The default limit is 2 hours.
If the -a option is specified, the use of the ftpaccess(5)
configuration file is enabled.
If the -A option is specified, use of the ftpaccess(5) con-
figuration file is disabled. This is the default.
If the -L option is specified, commands sent to the ftpd(8)
server will be logged to the syslog. The -L option is over-
ridden by the use of the ftpaccess(5) file. If the -L flag
is used, command logging will be on by default as soon as
the ftp server is invoked. This will cause the server to
log all USER commands, which if a user accidentally enters a
password for that command instead of the username, will
cause passwords to be logged via syslog.
If the -i option is specified, files received by the ftpd(8)
server will be logged to the xferlog(5). The -i option is
overridden by the use of the ftpaccess(5) file.
The -I option disables the use of RFC931 (AUTH/ident) to
attempt to determine the username on the client.
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FTPD(8) MAINTENANCE COMMANDS FTPD(8)
If the -o option is specified, files transmitted by the
ftpd(8) server will be logged to the xferlog(5). The -o
option is overridden by the use of the ftpaccess(5) file.
If the -X option is specified, the output created by the -i
and -o options is not saved to the xferlog file but saved
via syslog so you can collect output from several hosts on
one central loghost.
If the -u option is specified, the default umask is set to
umask.
If the -W option is specified user logins are not recorded
in the wtmp file. The default ( -w ) is to record every
login and logout.
The -s and -S options place the daemon in standalone opera-
tion mode. The -S option runs the daemon in the background
and is useful in startup scripts during system initializa-
tion (ie., in rc.local). The -s option leaves the daemon in
foreground and is useful when running from init (ie.,
/etc/inittab).
The -p and -P options override the port numbers used by the
daemon. Normally, the daemon determines the port numbers by
looking in /etc/services for "ftp" and "ftp-data". If there
is no /etc/services entry for "ftp-data" and the -P option
is not specified, the daemon uses the port just prior to the
control connection port. The -p option is only available if
running as a standalone daemon.
The -q and -Q options deterine whether the daemon uses the
PID files. These files are required by the limit directive
to determine the number of current users in each access
class. Disabling the use of the PID files disables user
limits. The default ( -q ) is to use the PID files.
Specify -Q when testing the server as a normal user when
access permissions prevent the use of the PID files. Large,
busy sites which do not wish to impose limits on the number
of concurrent users may also consider disabling the PID
files.
The -r option instructs the daemon to chroot(2) to the
specified rootdir immedeately upon loading. This can
improve system security by limiting the files which may be
damaged should a breakin occur through the daemon. Set is
much like anonymous FTP, with additional files needed which
vary from system to system.
The ftp server currently supports the following ftp
requests; case is not distinguished.
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FTPD(8) MAINTENANCE COMMANDS FTPD(8)
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 -lgA'')
MKD make a directory
MDTM show last modification time of file
MODE specify data transfer mode
NLST give name list of files in directory
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
REST restart incomplete transfer
RETR retrieve a file
RMD remove a directory
RNFR specify rename-from file name
RNTO specify rename-to file name
SITE non-standard commands (see next section)
SIZE return size of file
STAT return status of server
STOR store a file
STOU store a file with a unique name
STRU specify data transfer structure
SYST show operating system type of server system
TYPE specify data transfer type
USER specify user name
XCUP change to parent of current working directory (deprecated)
XCWD change working directory (deprecated)
XMKD make a directory (deprecated)
XPWD print the current working directory (deprecated)
XRMD remove a directory (deprecated)
The following non-standard or UNIX specific commands are
supported by the SITE request.
Request Description
UMASK change umask. E.g. SITE UMASK 002
IDLE set idle-timer. E.g. SITE IDLE 60
CHMOD change mode of a file. E.g. SITE CHMOD 755 filename
HELP give help information. E.g. SITE HELP
NEWER list files newer than a particular date
MINFO like SITE NEWER, but gives extra information
GROUP request special group access. E.g. SITE GROUP foo
GPASS give special group access password. E.g. SITE GPASS bar
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FTPD(8) MAINTENANCE COMMANDS FTPD(8)
EXEC execute a program. E.g. SITE EXEC program params
The remaining ftp requests specified in Internet RFC 959 are
recognized, but not implemented. MDTM and SIZE are not
specified in RFC 959, but will appear in the next updated
FTP RFC.
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. If a STAT
command is received during a data transfer, preceded by a
Telnet IP and Synch, transfer status will be returned.
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 four rules.
1) The user name must be in the password data base,
/etc/passwd, or whatever is appropriate for the operat-
ing system, and the password must not be null. 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) The user must have a standard shell returned by
getusershell(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, 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 super-user and unwrit-
able 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
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FTPD(8) MAINTENANCE COMMANDS FTPD(8)
support the list command. This program should have
mode 111.
~ftp/etc)
Make this directory owned by the super-user and unwrit-
able by anyone. The files passwd(5) and group(5) must
be present for the ls command to be able to produce
owner names rather than numbers. Depending on the
operating system, there may be other required files.
Check your manual page for the getpwent(3) library rou-
tine. The password field in passwd is not used, and
should not contain real encrypted passwords. These
files should be mode 444 and owned by the super-user.
Don't use the system's /etc/passwd file as the password
file or the system's /etc/group file as the group file
in the ~ftp/etc directory.
~ftp/pub)
Create a subdirectory in ~ftp/pub with the appropriate
mode (777 or 733) if you want to allow normal users to
upload files.
AUTHENTICATION MECHANISM ON BSD/OS SYSTEMS ONLY
The authentication mechanism used by ftpd is determined by
the ``auth-ftp'' entry in the /etc/login.conf file (see
login.conf(5)) that matches the users class. If there is no
``auth-ftp'' entry for the class, the normal ``auth'' entry
will be used instead. An alternate authentication mechanism
may be specified by appending a colon (``:'') followed by
the authentication style, i.e. ``joe:skey''.
GENERAL FTP EXTENSIONS
There are some extensions to the FTP server such that if the
user specifies a filename (when using a RETRIEVE command)
such that:
True Filename Specified Filename Action
------------- ------------------ -----------------------------------
<filename>.Z <filename> Decompress file before transmitting
<filename> <filename>.Z Compress <filename> before
transmitting
<filename> <filename>.tar Tar <filename> before transmitting
<filename> <filename>.tar.Z Tar and compress <filename> before
transmitting
Also, the FTP server will attempt to check for valid e-mail
addresses and chide the user if he doesn't pass the test.
For users whose FTP client will hang on "long replies" (i.e.
multiline responses), using a dash as the first character of
the password will disable the server's lreply() function.
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FTPD(8) MAINTENANCE COMMANDS FTPD(8)
The FTP server can also log all file transmission and recep-
tion, keeping the following information for each file
transmission that takes place.
Mon Dec 3 18:52:41 1990 1 wuarchive.wustl.edu 568881 /files.lst.Z a _ o a chris@wugate.wustl.edu ftp 0 *
%.24s %d %s %d %s %c %s %c %c %s %s %d %s
1 2 3 4 5 6 7 8 9 10 11 12 13
1 current time in the form DDD MMM dd hh:mm:ss YYYY
2 transfer time in seconds
3 remote host name
4 file size in bytes
5 name of file
6 transfer type (a>scii, b>inary)
7 special action flags (concatenated as needed):
C file was compressed
U file was uncompressed
T file was tar'ed
_ no action taken
8 file was sent to user (o>utgoing) or received from
user (i>ncoming)
9 accessed anonymously (r>eal, a>nonymous, g>uest) -- mostly for FTP
10 local username or, if guest, ID string given
(anonymous FTP password)
11 service name ('ftp', other)
12 authentication method (bitmask)
0 none
1 RFC931 Authentication
13 authenticated user id (if available, '*' otherwise)
SEE ALSO
ftp(1), getusershell(3), syslogd(8), ftpaccess(5), xfer-
log(5), umask(2)
BUGS
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.
Last change: Jan 10, 1997 6
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