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ftpd(1M) ftpd(1M)

NAME
ftpd - DARPA Internet File Transfer Protocol server

SYNOPSIS
timeout] maxtimeout] umask] size] number_of_tries] nice_value] rootdir] ctrlport] dataport]

DESCRIPTION
is the DARPA Internet File Transfer Protocol server. It expects to be run by the Internet daemon (see inetd(1M) and inetd.conf(4)). runs
when a service request is received at the port indicated in the service specification in (see services(4)).

Options
recognizes the following options and command-line arguments.

Enables the use of the configuration file
(see ftpaccess(4)).

Disables the use of the configuration file
(see ftpaccess(4)).

Sets the buffer size of the data socket to
size blocks of 1024 bytes. The valid range for size is from 1 to 2097151 (default is 56). A large buffer size will
improve the performance of on fast links, but may cause long connection times on slow links (for example, X.25).

If the buffer size needs to be set to any value other than multiples of 1024 bytes, use "B" immediately after size
without any space. The size value will be taken in terms of bytes. For example, to set the buffer size to a value
equal to "1500", use

Overrides the control and the data port numbers respectively that is
used by the daemon. Normally, the daemon determines the port numbers by looking in (see services(4)) for "ftp" and
"ftp-data". If there is no entry for "ftp-data" and the option is not specified, the daemon uses the port just prior
to the control connection port. The and options are both available if running as a standalone daemon. Otherwise,
only the option can be used.

Logs all the files received by
server to (see xferlog(5)). This option is overridden by the file. (see ftpaccess(4)).

Enables the use of RFC931 (AUTH/ident) to attempt to determine the
username on the client.

Applicable only in a secure environment based on Kerberos V5.
Causes access to be denied if network authentication fails. See sis(5).

Causes each FTP session to be logged in the
file.

Logs all commands sent to the
server to be logged to the The option is overridden by the file (see ftpaccess(4)). If the option is used, commands
will be logged to by default.

Specifies the number of tries for a
socket call.

Sets the nice value for an
process. When using this option, make sure that the nice clause in file (see ftpaccess(4)) is not set.

Logs all files transmitted by
to (see xferlog(5)). It logs outgoing files from the server. This option is overridden by the file (see ftpac-
cess(4)).

The default action of
does not allow usage of reserved ports as the originating port on the client's system; that is, the command cannot
specify a reserved port. This option allows the client to specify a reserved port. Note, allowing usage of reserved
ports can result in the misuse of The security ramifications should be understood before the option is turned on.

Enables third party transfer.

Determines whether the daemon uses the PID files.
These files are required by the directive to determine the number of current users in each access class. Disabling
the use of the PID files disables user limits. The default specifies to use the PID files. Specify to disable using
the PID files. The option can be used 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.

Instructs the daemon to chroot (see
chroot(2)) to the specified rootdir immediately upon loading. This can improve system security by limiting the files
which may be damaged should a break-in occur through the daemon. This option is like anonymous FTP. For this option
to work properly additional files may be needed under the specified rootdir, which can vary from system to system.

Runs the daemon in standalone operation mode.
The option runs the daemon in the background and is useful in startup scripts during system initialization (that is,
in The option leaves the daemon in foreground and is useful when running from (see init(1M)).

Causes to timeout inactive sessions after timeout seconds. By default, terminates an inactive session after 15 minutes. A
timeout value of implies that there is no timeout value and is set to an infinite timeout period. If timeout is set
to a value more than maxtimeout (see the option), timeout will be set to the maxtimeout value.

A client can also request a different timeout period.
The option sets to maxtimeout the maximum timeout that client can request, in seconds. By default, the maximum time-
out is 2 hours. A maxtimeout value of implies that there is no timeout value and is set to an infinite timeout
period.

Change default umask from 027 to umask.

Disables the use of
and uses for sending data. Use this option if the link cannot handle more than one buffer per packet (for example,
Gigabit Ethernet).

The debugging information is written to the
file.

Causes the program to display copyright and version information, then terminate.

Determines whether the user logins are to be recorded in the
and files. If the option is specified, user logins are not recorded in the wtmps or btmps file. The default is used
to record every login, logout, and bad login attempts.

Specifies that the output created by the
and options is not saved to the file but saved via so that the output can be collected from several hosts on one cen-
tral loghost.

currently supports the following commands (uppercase and lowercase are interpreted as equivalent):

Abort previous command

Specify account (ignored)

Allocate storage (vacuously)

Append to a file

Change to parent of current working directory

Change working directory

Delete a file

Sets the server to listen on a data port and wait for a connection

Use extended address for data connection

Give help information

Give list files in a directory

Use long address for data connection

Sets the server to listen on a data port and wait for a connection

Make a directory

Show last modification time of file

Specify data transfer
mode

Give name list of files in directory

Do nothing

Specify password

Prepare for server-to-server transfer

Specify data connection port

Print the current working directory

Terminate session

Restart incomplete transfer

Retrieve a file

Remove a directory

Specify rename-from file name

Specify rename-to file name

Non-standard commands (see next section)

Return size of file

Return status of server

Store a file

Store a file with a unique name

Specify data transfer
structure

Show operating system type of server system

Specify data transfer
type

Specify user name

Change to parent of current working directory

Change working directory

Make a directory

Print the current working directory

Remove a directory

The following commands are supported when is operating in a secure environment which is based on Kerberos V5 (see sis(5)).

Command Description

Authentication/security mechanism

Authentication/security data

Clear command channel

Privacy protected command

Integrity protected command

Data channel protection level (level "C" only)

Protection buffer size (has no effect)

These commands are described in draft 8 of the FTP security extensions.

The following non-standard or HP-UX specific commands are supported by the command:

Change umask (for example,

Set idle-timer (for example,
60).

Change mode of a file (for example,
filename).

Give help information (for example,

List files newer than a particular date.

Works like but gives extra information.

Request for special group access (for example,

Give special group access password (for example,

Execute a program (for example,

For the command, in order to execute a program it has to be placed in the directory. The program to be executed must be either a binary
program file or a valid shell. For example for the following program:

When we give the following command:

The output will be as follows:

The security of the system will entirely be dependent on what binaries or shell programs that the administrator has placed in the directory
Making this functionality available to real users who have shell access does not have any major security ramifications, but for anonymous
and guest users who do not have shell access, it does.

The remaining FTP requests specified in Internet RFC 959 are recognized, but not implemented. and are not specified in RFC 959, but are
expected in the next updated

The FTP server aborts an active file transfer only when the 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. If receives a command during a data transfer, preceded by a
Telnet IP and Synch, it returns the status of the transfer.

interprets file names according to the "globbing" conventions used by This allows users to utilize the metacharacters and

authenticates users according to three rules:

o The user name must be in the password data base, and not have a null password. The client must provide the correct password for the
user before any file operations can be performed.

o The user name must not appear in the file (see ftpusers(4)).

o The user must have a standard shell returned by

Optionally, a system administrator can permit public access or "anonymous FTP." If this has been set up, users can access the anonymous
FTP account with the user name or and any non-null password (by convention, the client host's name). does a to the home directory of user
thus limiting anonymous FTP users' access to the system. If the user name is or an anonymous FTP account must be present in the password
file (user In this case the user is allowed to log in by specifying any password (by convention this is given as the user's e-mail
address).

In order to permit anonymous FTP, there must be an entry in the database for an account named The password field should be the group mem-
bership should be and the login shell should be For example (assuming the group ID is

The anonymous FTP directory should be set up as follows:

The home directory of the FTP account should be owned by user
and mode 555 (not writable). Since does a to this directory, it must have the following subdirectories and files:

This directory must be owned by root and mode 555 (not writable).
The file should be copied to This is needed to support directory listing by The command should be mode 111 (executable
only). If the FTP account is on the same file system as can be hard link, but it may not be a symbolic link, because of
the The command must be replaced when the system is updated.

The file can also be copied to the directory in place of However, if this is done, a set of relevant libraries must also
be copied under the directory See the for details of required libraries. The directory must be owned by root and mode
555 (not writable). All the libraries copied under this directory must be mode 555 (not writable).

This directory must be owned by root and mode 555 (not writable).
It should contain versions of the files passwd and group. See passwd(4) and group(4). These files must be owned by root
and mode 444 (readable only). These files must be present for the command to be able to produce owner names rather than
numbers.

This file should contain entries for the
user and any other users who own files under the anonymous directory. Such entries should have for passwords. Group IDs
must be listed in the anonymous FTP group file, The path names of home directories in must be with respect to the anony-
mous FTP home directory.

This file should contain the group names associated with
any group IDs in file and any group IDs of files in the anonymous FTP subdirectories.

This directory is used by anonymous FTP users to deposit files
on the system. It should be owned by user and should be mode 777 (readable and writable by all).

Directories used to make files available to anonymous FTP users
should be mode 555 (not writable), and any files to be distributed should be owned by root and mode 444 (readable only)
so that they cannot be modified or removed by anonymous FTP users.

The steps that are followed to create an anonymous account are used to create a guest account also.

DIAGNOSTICS
replies to FTP commands to ensure synchronization of requests and actions during file transfers, and to indicate the status of Every com-
mand produces at least one reply, although there may be more than one. A reply consists of a three-digit number, a space, some text, and
an end of line. The number is useful for programs; the text is useful for users. The number must conform to this standard, but the text
can vary.

The first digit of the message indicates whether the reply is good, bad, or incomplete. Five values exist for the first digit. The values
and the interpretations of the values are:

1 The requested action is being initiated; expect another reply before proceeding with a new command.

2 The requested action is complete. The server is ready for a new request.

3 The command has been accepted, but the requested action requires more information.

4 The command was not accepted, the requested action failed, but the error condition is temporary and the action can be
requested again.

5 The command was not accepted, the requested action failed, and the error condition would most likely occur again if the same
command sequence is repeated.

The second digit indicates the functional area that the message addresses. The values of the second digit and the interpretations of these
values are:

0 Syntax. A message with a 0 for the second digit indicates that a syntax error occurred.

1 Information. A message with a 1 as the second digit indicates that the message is in reply to a request for information.

2 Connections. A message with a 2 as the second digit indicates that the message is a reply to a request for control and data
connection information.

3 Authentication and accounting. A message with a 3 as the second digit indicates that the message is a reply to a login or
accounting procedure.

4 Not currently specified.

5 File system. A message with a 5 as the second digit indicates that the text following the number contains information con-
cerning the status of the server file system.

The third digit provides a further clarification of the information supplied by the second digit. Following are several examples of mes-
sages. Note that replies match the number but not the text.

110 Restart marker reply. MARK where yyyy is a user process data stream marker, and mmmm is equivalent marker
120 Service ready in nnn minutes
200 Command okay
211 System status, or system help reply
212 Directory status
230 User logged in, proceed
250 Requested file action okay, completed
331 User name okay, need password
350 Requested file action pending further information
425 Cannot open data connection
451 Requested action aborted: local error in processing
500 Syntax error, command unrecognized or command line too long
530 Not logged in
550 Requested action not taken; file unavailable, not found, no access

GENERAL FTP EXTENSIONS
There are some extensions to the FTP server such that if the user specifies a filename (when using a RETRIEVE command), the following
actions will occur:

True Filename Specified Filename Action
------------------------------------------------------------------
filename.Z filename Decompress (uncompress) 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 notify the user if invalid e-mail addresses are found. For users
whose FTP client will hang on "long replies" (that is, multiline responses), using a dash as the first character of the password will dis-
able this "long replies" feature.

Users whose password starts with a dash, have to use an extra dash in the beginning of the password for login to succeed. However, the
"long replies" feature will be disabled in this case.

The FTP server can also log all file transmission and reception, keeping the following information for each file transmission that takes
place.

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)
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)

WARNINGS
The password is sent unencrypted through the socket connection.

Anonymous FTP is inherently dangerous to system security.

DEPENDENCIES
Pluggable Authentication Modules (PAM)
PAM is an Open Group standard for user authentication, password modification, and validation of accounts. In particular, is invoked to
perform all functions related to login. This includes retrieving the password, validating the account, and displaying error messages.

supports only a single password, unlike the and commands. will not work properly if it uses multiple modules in the file.

AUTHOR
was developed by the University of California, Berkeley and the Washington University, St. Louis, Missouri.

SEE ALSO
ftp(1), inetd(1M), chroot(2), send(2), sendfile(2), pam_authenticate(3), getusershell(3C), ftpaccess(4), ftpusers(4), group(4),
inetd.conf(4), passwd(4), sis(5), xferlog(5).

ftpd(1M)

hpux man page for ftpd