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opieftpd

Langue: en

Version: 10 January 1995 (openSuse - 09/10/07)

Section: 8 (Commandes administrateur)

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 transfer, preceded by a Telnet IP and Synch, transfer status will be returned. opieftpd interprets file names according to the globbing conventions 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

Nous oublions aisément nos fautes lorsqu'elles ne sont sues que de nous.
-+- François de La Rochefoucauld (1613-1680), Maximes 196 -+-