[HECnet] VMS FTP server?

[Johnny Billquist]

On 2015-01-08 03:22, Paul_Koning at Dell.com wrote:

On Jan 7, 2015, at 9:03 PM, Johnny Billquist <bqt at softjar.se> wrote:

Thanks. (I doubt the VMS ftp server would care about NAT, it's not something the system behind a NAT knows or should care about. It's the NAT router who have to do all the work   )

Usually, but it depends on the protocol.   Some protocols     FTP is a notorious example     carry addresses and/or port numbers inside the application protocol data.

Right. And most any NAT box I know of knows this, and actually snoop the ftp control session to catch this so it can work.
But you are absolutely correct in that it is an extra level of excitement.

Does this server support passive mode?   A lot of NAT servers need passive mode for FTP to work, or work more reliably if you use passive mode.   (I just like passive mode because it isn   t quite so conceptually broken as the older mode of FTP.)

I don't know about the VMS one. Mine do. :-)

But passive mode was in ftp already from the start, so anyone not implementing it would be rather silly. It is also required if you ever want to initiate a transfer between two boxes, if you yourself is on a third box.

And yes, passive mode is much easier for NAT to handle, since it looks much more like any normal session coming through. No need to snoop the ftp control channel in this case.

	Johnny

-- 
Johnny Billquist                                   || "I'm on a bus
                                                                  ||   on a psychedelic trip
email: bqt at softjar.se                         ||   Reading murder books
pdp is alive!                                         ||   tryin' to stay hip" - B. Idol