On Wed, 15 Dec 1999, David Zverina wrote:
> > However, people who have used passive and UDP FTP know that UDP is faster
> > and that's why ip_masq_ftp was created.
>
> It's been a while since I read the FTP RFC but if I do remember correctly:
>
> 1. FTP uses TCP only (FSP uses UDP)
My mistake then :) I thought the port 20 returned via UDP and used the
TCP channel for packet acknowledgements, etc thus creating a more
stream-like connection.
> 2. As mention before it uses one port for data (20) and one port for
> control (21). When you download a file, your local PC binds and listens to a
> random port and then sends the port to the server. Server then connects from
> the data port and sends you the file. This will not work when masquerading
> because when your PCs binds to a local port the port is not exposed to the
> internet. ip_masq_ftp knows about ftp connections and when it sees a local
> port being sent it sets up a port that is exposed to the internet on the
> gateway, rewrites the packet so that the ftp server sends the data to it and
> redirects traffic from the gateway port to your local port. Thus FTP works
> again.
Yah, I know what it does and how it works :) I'm having enough fun
with ip_masq_icq hacking right now :)
Andrew.
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