On Mon, Oct 09, 2000 at 09:34:23AM +0200, Philipp Snizek wrote:

Hello

Please can somebody tell me the difference between active ftp and passive ftp?

thank you Philipp

If you do some ftp then you have a server somewhere in the world and a client program on your system. The servers runs day after day and waits for connections, he 'listens' on a port (usually port 21). The client connects to that port and then the client sends commands, and the server responses if you are lucky. To transfer data (after a get or put command perhaps) they do NOT use this existing connection, they open another one instead. But which of both plays the the server (listening) and which plays the client (connecting) to establisg this second channel? - If the client chooses the 'passive' mode, then he sends a PASV command to the server. The server opens a port for the data connection (usually port 20 I believe) and sends an answer to the client containing the host adresse. The client connects to this adress/port combination. - If the client chooses the 'active' mode, then he creates the listening side of the connection, sends his adress to the server, and the server connects. Since in passive mode the server sends an adress it is able to let the client connect to any other server (gateway) by sending the appropriate adress. Klaus -- ---------------------------------------------------------------------- Klaus Wachtler Breidingstr. 17 D-29614 Soltau Tel. +49-5191-70271, +49-171-4553039 Fax: +49-5191-70272 email AnyWare@Wachtler.de http://www.wachtler.de ----------------------------------------------------------------------