OPIEFTPD(8)						      System Manager's Manual						       OPIEFTPD(8)

NAME

       opieftpd - File Transfer Protocol server that uses OPIE authentication

SYNOPSIS

       opieftpd [-d] [-l] [-t timeout ] [-T maxtimeout ] [-u umask ]

DESCRIPTION

       opieftpd  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 services(5).

OPTIONS

       -d     Debugging information is written to the system logs.

       -l     Each ftp(1) session is logged in the system logs.

       -t     The inactivity timeout period is set to timeout seconds (the default is 15 minutes).

       -T     A client may also request a different timeout period; the maximum period allowed may be  set  to	maxtimeout  seconds  with  the	-T
	      option. The default limit is 2 hours.  -u Set the default umask value to umask.

COMMANDS

       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 a list of files in a directory
       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 file)
       HELP	    give help information (e.g. 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 RFC-959.  If a STAT command is received during a  data  trans-
       fer, preceded by a Telnet IP and Synch, transfer status will be returned.  opieftpd interprets file names according to the globbing conven-
       tions used by csh(1).  This allows users to utilize the metacharacters *?[]{}~.

       opieftpd authenticates users according to three rules:

       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 performed.

       The user name must not appear in the file /etc/ftpusers.

       The user must have a standard shell returned by getusershell(3).

       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, opieftpd 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.

       ~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 command.
	      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(1)
	      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.

       ~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

       ftpd(8), ftp(1), opie(4), opiekey(1), opiepasswd(1), opieinfo(1), opiesu(1), opieftpd(8), opiekeys(5), opieaccess(5)

BUGS

       The anonymous account is inherently dangerous and should avoided when possible. In opieftpd, it is a compile-time  option  that	should	be
       disabled  if  it is not being used.  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 scrutinized, but are possibly incomplete.

HISTORY

       The ftpd command appeared in 4.2BSD.

AUTHOR

       Originally written for BSD, ftpd was modified at NRL by Randall Atkinson, Dan McDonald, and Craig Metz to support OTP authentication.

CONTACT

       OPIE is discussed on the Bellcore "S/Key Users" mailing list. To join, send an email request to:

       skey-users-request@thumper.bellcore.com

								  10 January 1995						       OPIEFTPD(8)