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- Jan 28, 1993 FTPD(8)
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- NAME
- ftpd - DARPA Internet File Transfer Protocol server
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- SYNOPSIS
- ftpd [ -d ] [ -l ] [ -ttimeout ] [ -Tmaxtimeout ] [ -a ] [ -A ] [ -L ] [
- -i ] [ -I ] [ -o ] [ -O ]
-
- 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(5).
-
- If the -d 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) configuration
- file is disabled.
-
- If the -L option is specified, commands sent to the ftpd(8) server will
- be logged to the syslog. The -L option is overridden by the ftpac-
- cess(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 ftpac-
- cess(5) file.
-
- If the -o option is specified, files transmitted by the ftpd(8) server
- will be logged to the syslog. The -o option is overridden by the ftpac-
- cess(5) file.
-
- 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
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- 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)
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- The following non-standard or UNIX specific commands are supported by
- the SITE request.
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- 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
- EXEC execute a program. E.g. SITE EXEC program params
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- 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.
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- 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. 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, AmiTCP:db/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.
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- 2) The user name must not appear in the file AmiTCP:db/ftpusers.
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- 3) The user must have a standard shell returned by getusershell(3).
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- 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 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 anyone.
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- ~ftp/bin
- Make this directory owned by the super-user and unwritable by any-
- one. The program ls(1) must be present to support the list com-
- mand. This program should have mode 111.
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- ~ftp/etc
- Make this directory owned by the super-user and unwritable by any-
- one. The files passwd(5) and group(5) must be present for the ls
- command to be able to produce owner names rather than numbers. The
- password field in passwd is not used, and should not contain real
- encrypted passwords. These files should be mode 444.
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- ~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.
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- GENERAL FTP EXTENSIONS
-
- There are some extensions to the FTP server such that if the user speci-
- fies 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
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- 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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- The FTP server can also log all file transmission and reception, keeping
- the following information for each file transmission that takes place.
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- 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
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- 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) -- 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)
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- SEE ALSO
- ftp(1), getusershell(3), syslogd(8), ftpaccess(5), xferlog(5)
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- BUGS
- The anonymous account is inherently dangerous and should avoided when
- possible.
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- 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 pos-
- sibly incomplete.
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