Ata@RADC-MULTICS.ARPA ("John G. Ata") (04/13/87)
Date: 12 April 1987 13:33 edt
From: Joe I. Herman <dzoey at TERMINUS.UMD.EDU>
Subject: Re: FTP client program
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The well know data port for FTP is port 20. You can change this by
issuing the PORT command to the host before you issue a STOR or
RETR. I forget the exact syntax for the PORT command, but it's in
the RFC.
Port 20 is the well known data port for the FTP Server. It cannot be
changed by having the client FTP send the port command to the Server.
This only changes the port that the client FTP uses which is usually NOT
port 20. The server may change from port 20 by issuing the PORT command
to the client.
example
user wants to stor data:
client: PORT x
server: {200,250} PORT command okay
client: listen on x
client: STOR foo
server: {150,125} Establishing connection {opens a tcp connection to port x}
If you want more info, I'll be glad to help.
Joe Herman
dzoey@umd5.umd.edu
Again, this changes the port that the client listens on, not the
server's use of port 20. I didn't get a copy of the original message
that started this, but hope that it helps.
John G. AtaAta@RADC-MULTICS.ARPA ("John G. Ata") (04/13/87)
Actually, my original message had a typo...the server may NOT change the
well known port 20 by issuing the PORT command. (The only way I know
how to change the server port is by having the client issue the PASV
command, but this does more than allow for a port change.) Sorry for
the confusion...
John G. Ata