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Ulm's Oberon System:
adis-ftpsession

NAME

adis-ftpsession - run FTP session

SYNOPSIS

adis-ftpsession [-c] [-m umask] [-t timeout] [-u|-U] root-directory

DESCRIPTION

adis-ftpsession runs a pipelining FTP session that requires no further authorization on the bidirectional network connection passed via file descriptor 0. Access is provided to root-directory and its sub directories.

Following options are supported:

-c: suppress the latency reducing technique that opens IP addresses provided by PORT commands immediately after seeing them. Instead, wait until a command is issued that utilizes a data connection. Note that adis-ftpsession falls automatically into this mode on the first failure of an early connect.
-m umask: set the umask of the FTP server to umask which is to be given in octal. This is useful to override a too restrictive default in case of FTP logins that access directories shared by a group.
-t timeout: sets the timeout to timeout seconds. A timeout of 0 switches off the timer. By default, there is a time limit of 600 seconds of inactivity after which a session will be hung up by adis-ftpsession.
-u: enable non-destructive uploads, i.e. files and directories may be created as long existing files and directories are not harmed. Rename operations are not permitted.
-U: provide unrestricted write access.

adis-ftpsession may be called directly by a port listener (tcpserver, for example) to provide anonymous FTP service or indirectly under the application of adis-ftplogin (to read in the credentials) and any checkpassword plug-in (adis-ftplogin, for example).

The set of FTP commands implemented by FTPSessions, FTPDataStreams, and FTPUnixFileSystems is provided. Note that USER, PASS, and ACCT are always responded with a code of 230, indicating that access is already granted.

adis-ftpsession supports pipelining (see FTPEngine) according to http://cr.yp.to/ftp/pipelining.html.

DIAGNOSTICS

adis-ftpsession creates a pipeline to /var/qmail/bin/splogger to log all processed commands together with the return codes to syslog (auth.info).

FILES

There are no configuration files.

SECURITY CONSIDERATIONS

adis-ftplogin should never be run under root privileges. Instead normal user privileges are best for user configured FTP logins (see adis-ftplogin), and, in case of anonymous FTP servers, a special user ID that does not own any files should be chosen.

The security considerations of FTPUnixFileSystems and FTPDataStreams apply.

EXAMPLE

To set up an anonymous FTP service on a non-privileged port (9030 in this example) is pretty easy using tcpserver and adis-ftpsession. The only tricky part is to create a FTP greeting in a shell variable that ends in CR LF:

hi="`echo '220 Hi!\r'`
"
tcpserver -B "$hi" 0 9030 adis-ftpsession ~/pub/ftp

Ulm's Oberon System: adis-ftpsession