On 2015-01-08 17:57, Mark Pizzolato - Info Comm wrote: On Thursday, January 08, 2015 at 8:38 AM, Johnny Billquist wrote: On 2015-01-08 17:02, Paul_Koning at Dell.com wrote: On Jan 7, 2015, at 10:43 PM, Johnny Billquist <bqt at softjar.se> wrote: So the question is - what do VMS do when talking to another VMS system, and how does VMS decide when to use the extra abilities? If there isn t a spec, the alternative would be to capture an FTP session with a tool like Wireshark, and reverse engineer things. That tends to be a pain but it can be done if all else fails. Yeah. At this point I suspect that would be the easiest. Sending a really small file over should tell me enough, I think. Anyone who have both a VMS client and server, and some machine inbetween that can run tcpdump or similar, and who could get me a dump of a simple file? Please keep in mind that any passwords you enter in the session will also be in such a log... I did the Wireshark trace and doing a GET there is an initial exchange of STRU O VMS and if the comes back with a "200 OK" the client knows that the server is VMS and probably viceversa. Then the data delivered in the RETR (separate TCP session as normal) is prefixed with a binary blob of data. The format of that blob is important. I recalled that MadGoat FTP also implemented this functionality (and interoperated with it - Matt Madison (of MadGoat) ended up working for the MultiNet folks for a while). In any case, over the years MGFTP became completely open source and is still maintained by Hunter Goatley (the Goat part of MadGoat). The source is available, but digging through the bliss code seemed a little harder than asking Hunter Goatley directly which I've done. I'll let you know what he says. Aha! That is really good information. Now I just wonder if it always tries this trick, or only if the other side identifies itself as a VMS system. Could you do the same test against a Unix system and see if it tries the STRU command there too? The binary blob is what I need to figure out next... Meanwhile, the HGFTP stuff is available at: http://vms.process.com/ftp/vms-freeware/fileserv/hgftp.zip Thanks. Might be worth looking into. As of now, Text transfers to and from RSX works fine, and I've extended the directory output a little. I'm wondering if I should bother trying to fool things like web browsers next, as they also tries to be clever and tries to understand a Unix-style directory output. Johnny