4.3BSD - /usr/man/cat8/ftpd.0

FTPD(8C)                                                              FTPD(8C)


NAME
       ftpd - DARPA Internet File Transfer Protocol server

SYNOPSIS
       /etc/ftpd [ -d ] [ -l ] [ -ttimeout ]

DESCRIPTION
       Ftpd  is  the  DARPA  Internet File Transfer Prototocol 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  sys‐
       log.

       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.

       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 -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 Internet  RFC  959  are  recog‐
       nized, but not implemented.

       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.

       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.

       1)     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‐
              formed.

       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  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‐
              one.

       ~ftp/bin)
              Make this directory owned by the super-user  and  unwritable  by
              anyone.   The  program ls(1) must be present to support the list
              commands.  This program should have mode 111.

       ~ftp/etc)
              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
              444.

       ~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.

SEE ALSO
       ftp(1C), getusershell(3), syslogd(8)

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 incomplete.


4.2 Berkeley Distribution       April 27, 1985                        FTPD(8C)