Hmmm... I still don't see what the problem was this is trying to get round. I run two FTP servers at different sites, and have never had any router/firewall problems as they both tell the client to use Passive mode, so the client only ever makes outgoing connections, and by default, any router/firewall that will allow an outgoing connect, will pass any replies back, for any number of opened data channels.
It's usualy the server end that needs holes poked in the firewall, and or port forwarding setup on the router. After all, Passive mode was specificaly developed to make the client side much easier so users and customers etc, don't have to mess with their security settings. I also keep well away from using port 21 for anything exposed to the www. It must be one of the most highly probed ports on the net, after the usual windows offerings and port 80. Oh well.. Dave B. > -----Original Message----- > From: Arno Garrels [mailto:[EMAIL PROTECTED] > Sent: 19 September 2008 09:52 > To: ICS support mailing > Subject: Re: [twsocket] Single port FTP > > Dave Baxter wrote: > > Mind you, how would you handle simultaneous connections to one port > > anyway... At present, I don't think it's possible without > > alterations > > to everyone's TCP/IP stack? Unless someone knows better. > > No problem, the client establishes a second connection to Port > 21 and tells the server to treat this second connection as > the data connection. > > -- > Arno Garrels > > > > > As above, what's wrong with Passive (or PASIV) mode? > > > > Cheers. > > > > Dave B > > > >> -----Original Message----- > >> From: Angus Robertson - Magenta Systems Ltd > >> [mailto:[EMAIL PROTECTED] > >> Sent: 16 September 2008 18:11 > >> To: email@example.com > >> Subject: [twsocket] Single port FTP > >> > >> We all know of the problems caused by the FTP data connection with > >> NAT routers, firewalls, etc, so it's interesting someone > has come up > >> with an RFC proposal that allows the data connection to > also run on > >> port 21. > >> > >> http://www.ietf.org/internet-drafts/draft-rosenau-ftp-single-p > >> ort-04.txt > >> > >> Essentially, a second connection is opened to port 21, > with a simple > >> logon process to tie it to the initial 21 connection, then > the real > >> data sent after a 200 DATA response. > >> > >> - The control connection ("--1-->") is established. > >> S--1-->C 220 FTP server ready<CRLF> > >> C--1-->S USER u001<CRLF> > >> S--1-->C 331 Enter password<CRLF> > >> C--1-->S PASS xyz<CRLF> > >> S--1-->C 230 You are logged in<CRLF> > >> C--1-->S SPSV<CRLF> > >> S--1-->C 227 Entering single-port mode (xYab1234)<CRLF> > >> - The data connection ("---2->") is established > >> S---2->C 220 FTP server ready<CRLF> > >> C---2->S SPDT xYab1234<CRLF> > >> S---2->C 200 DATA<CRLF> > >> C--1-->S RETR contents.txt<CRLF> > >> S--1-->C 150 Transmitting data<CRLF> > >> S---2->C (Contents of contents.txt) > >> - The server closes the data connection ("---2->") > >> S--1-->C 226 Data transferred<CRLF> > >> ... > >> > >> Angus > >> > >> > >> > > This mail has been scanned by Palmer Cook Computer Services > Limited. > > www.palmercook.co.uk > > This mail has been scanned by Palmer Cook Computer Services Limited. www.palmercook.co.uk -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be