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Manpages FTPDSection: Maintenance Commands (8)Updated: Jan 10, 1997 Index Return to Main Contents NAMEftpd - Internet File Transfer Protocol serverSYNOPSISftpd [ -d ] [ -v ] [ -l ] [ -t timeout ] [ -T maxtimeout ] [ -a ] [ -A ] [ -L ] [ -i ] [ -I ] [ -o ] [ -p ctrlport ] [ -P dataport ] [ -q ] [ -Q ] [ -r rootdir ] [ -R ] [ -s ] [ -S ] [ -u umask ] [ -V ] [ -w ] [ -W ] [ -X ]DESCRIPTIONFtpd 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).The -V option causes the program to display copyright and version information, then terminate. If the -d or -v 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. This is the default. 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 use of the ftpaccess(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 use of the ftpaccess(5) file. The -I option disables the use of RFC931 (AUTH/ident) to attempt to determine the username on the client. If the -o option is specified, files transmitted by the ftpd(8) server will be logged to the xferlog(5). The -o option is overridden by the use of the ftpaccess(5) file. If the -X option is specified, the output created by the -i and -o options is not saved to the xferlog file but saved via syslog so you can collect output from several hosts on one central loghost. If the -u option is specified, the default umask is set to umask. If the -W option is specified user logins are not recorded in the wtmp file. The default ( -w ) is to record every login and logout. The -s and -S options place the daemon in standalone operation mode. The -S option runs the daemon in the background and is useful in startup scripts during system initialization (ie., in rc.local). The -s option leaves the daemon in foreground and is useful when running from init (ie., /etc/inittab). The -p and -P options override the port numbers used by the daemon. Normally, the daemon determines the port numbers by looking in /etc/services for "ftp" and "ftp-data". If there is no /etc/services entry for "ftp-data" and the -P option is not specified, the daemon uses the port just prior to the control connection port. The -p option is only available if running as a standalone daemon. The -q and -Q options deterine whether the daemon uses the PID files. These files are required by the limit directive to determine the number of current users in each access class. Disabling the use of the PID files disables user limits. The default ( -q ) is to use the PID files. Specify -Q when testing the server as a normal user when access permissions prevent the use of the PID files. Large, busy sites which do not wish to impose limits on the number of concurrent users may also consider disabling the PID files. The -r option instructs the daemon to chroot(2) to the specified rootdir immedeately upon loading. This can improve system security by limiting the files which may be damaged should a breakin occur through the daemon. Set is much like anonymous FTP, with additional files needed which vary from system to system. When started with -R the daemon will not honour the REST command, possibly preventing "download managers" from hogging your bandwidth. 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 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 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 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. 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.
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.
AUTHENTICATION MECHANISM ON BSD/OS SYSTEMS ONLYThe authentication mechanism used by ftpd is determined by the ``auth-ftp'' entry in the /etc/login.conf file (see login.conf(5)) that matches the users class. If there is no ``auth-ftp'' entry for the class, the normal ``auth'' entry will be used instead. An alternate authentication mechanism may be specified by appending a colon (``:'') followed by the authentication style, i.e. ``joe:skey''.GENERAL FTP EXTENSIONSThere are some extensions to the FTP server such that if the user specifies 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 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. The FTP server can also log all file transmission and reception, keeping the following information for each file transmission that takes place.
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 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, g>uest) -- 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) SEE ALSOftp(1), getusershell(3), syslogd(8), ftpaccess(5), xferlog(5), umask(2)BUGSThe 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.
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