 |
Index for
Section 8 |
|
 |
Alphabetical
listing for F |
|
 |
Bottom of
page |
|
ftpd(8)
NAME
ftpd - Describes File Transfer Protocol server daemon, including anonymous
service
SYNOPSIS
ftpd [-dl] [-ttimeout] [-Tmaxtimeout]
FLAGS
-d Debugging information is sent to the syslogd daemon (see
syslogd(8)).
-l Each FTP session, as well as additional information, such as the file
name retrieved or stored, the number of bytes, and the attempted logins
that failed, is sent to the syslogd daemon (see syslogd(8)).
-ttime-out
The inactivity time-out period will be set to time-out seconds.
-Tmaxtime-out
The maximum timeout period allowed may be set to timeout seconds with
this option.
SECURITY NOTE
This security-sensitive command uses the SIA (Security Integration
Architecture) routine as an interface to the security mechanisms. See
matrix.conf(4) for more information.
DESCRIPTION
The ftpd command is the DARPA (Defense Advanced Research Projects Agency)
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(4).
The ftpd command includes two flags to control the information logged for
the ftpd daemon. If the -d flag is specified, debugging information is
logged. If the -l flag is specified, each ftp session, along with data for
login failures and file operations, is logged. Refer to the syslogd(8)
reference page for information on system log files.
The FTP server will time out an inactive session after 15 minutes. If the
-t flag is specified, the inactivity time-out period will be set to time-
out seconds. A client may also request a different time-out period; the
maximum period allowed may be set to time-out seconds with the -T flag. The
default limit is 2 hours.
If you want to use a customized banner, create an /etc/banner file. The
ftpd daemon reads the file, if it exists, and writes its contents over a
new FTP connection prior to starting the login dialog.
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 -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 Nonstandard 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 username
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 nonstandard or UNIX compatible commands are supported by the
SITE request:
Request Description
UMASK Change umask (for example, SITE UMASK 002)
IDLE Set idle timer (for example, SITE IDLE 60)
CHMOD Change mode of a file (for example, SITE CHMOD 755 filename)
HELP Give help information (for example, SITE HELP)
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 Telnet stream, as described in Internet RFC959.
If a STAT command is received during a data transfer, preceded by a Telnet
IP and Synch, transfer status will be returned.
The ftpd command interprets file names according to the ``globbing''
conventions used by the C shell (see csh(1)). This interpretation allows
users to utilize the metacharacters ``*?[]{}~''.
The ftpd command authenticates users according to four rules:
· The username must be in the password database, /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.
· The username must not appear in the /etc/ftpusers file.
· The user must have a standard shell returned by the getusershell()
call (see getusershell(3)).
· 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).
The ftp command uses the default Type-of-Service values recommended by
RFC1060, which are as follows:
ftp-control
Low delay
ftp-data
High throughput
Anonymous FTP Configuration
If you are creating an anonymous FTP account, ftpd takes special measures
to restrict the client's access privileges when the user logs in. The
server executes a chroot call (see chroot(2)) to the home directory of the
ftp user. In order that system security is not breached, it is recommended
that you adhere to the following rules when creating directories and files
in the ftp subtree:
~ftp
Make the home directory owned by the superuser (root) and unwritable by
anyone.
~ftp/bin
Make this directory owned by the superuser and unwritable by anyone.
The ls program (see ls(1)) must be present to support the list command.
This program should have mode 111.
Copy the ls program from /sbin/ls. This is the statically linked
version of the ls command, which does not require shared library
support. Be sure to copy the static version of ls from the /sbin
directory, not the shared version from the /usr/bin directory.
~ftp/etc
Make this directory owned by the superuser and unwritable by anyone.
The passwd and group files (see passwd(4) and group(4) ) must be
present for the ls command to be able to produce owner names rather
than numbers. The password field in the passwd file is not used, and
should not contain real encrypted passwords. These files should be
mode 444.
In this environment, the sia subdirectory (which you can copy from
/etc/sia) must also be present for the ls command to be able to produce
owner names rather than numbers.
~ftp/pub
Make this directory mode 777 and owned by ftp. Users should then place
files that are to be accessible via the anonymous account in this
directory.
You can configure these values by specifying them in the /etc/iptos file.
For more information, see iptos(4).
FILES
/usr/sbin/ftpd
Specifies the command path.
/etc/ftpusers
Contains the list of unauthorized users.
/etc/banner
Specifies the path name for the banner file.
CAUTIONS
The anonymous account is inherently dangerous and should be avoided when
possible.
The server must run as the superuser to create sockets with privileged port
numbers. It maintains an effective user ID of the logged in user,
reverting to the superuser only when binding addresses to sockets. The
possible security holes have been extensively scrutinized, but are possibly
incomplete.
RELATED INFORMATION
Commands: ftp(1), syslogd(8)
Functions: getusershell(3)
Files: iptos(4)
|
Index for
Section 8 |
|
|
Alphabetical
listing for F |
|
 |
Top of
page |
|