Problems uploading to Serv-U in FTPS SSL/TLS mode

[mfichtner]

Hi,

I'm currently testing Yummy FTP, and so far I'm quite impressed.

I did, however, come across what looks like some timing bug: I'm trying to upload two files to a Serv-U server, connected in FTPS SSL/TLS mode. I'm doing this by dragging those two files either from Mail.app or from the Finder into Yummy's window. In both cases, Yummy uploads the first file without any problems and then enters into an endless loop of waiting for a file list, trying to re-connect to the server, trying to upload the second file, trying to re-connect, trying to upload and so on. At this point, CPU load remains at an almost steady 100 percent.

I don't see this problem when uploading those same two files one after the other. I also don't see any problem when uploading the two files together to a different (Unix-based) SFTP-Server.

So, it looks like there's a problem either with uploading more than one file at a time in FTPS SSL/TLS mode, or with uploading more than one file at a time to a Serv-U server.

Is this a known issue? Is there a chance it'll get fixed in the near future?

I'd like to purchase the software within the next 15 hours or so -- but am a bit relucant to do so when something I'd use it for quite regularly doesn't work.

Thanks,
Sam

[JD]

Hi there

Certainly, this isn't a previously reported problem, and FTPS SSL/TLS has been transferring thousands of files to a variety of servers without any problems. I must admit I didn't try Serv-U FTP, though, so I'll come back with results once I've done that. In the meantime, please select Save FTP Transcript from the File menu when this problem occurs and send me the resulting file - support at yummysoftware dot com

As for the special offer period, I'm sure that I'll be able to sort out this problem you're having but I can't guarantee that it will be before the offer period runs out. If that's the case, and you're still interested once the problem is resolved, I'll give you a discount to get the offer price anyway

[mfichtner]

Oh, I certainly didn't expect you to fix this problem before the offer period runs out. Your response convinced me that it will be fixed. So I just ordered my copy.

I e-mailed you the FTP transcript, and I also did some more testing myself. Two things I noticed:

(1) I can work around the problem by configuring Yummy FTP so that it only uses a single connection -- even though the Serv-U server is configured to accept an unlimited number of connections for the login I'm using.

(2) Yummy seems to be sending invalid PORT commands using the machine's private IP address:

Code: [Select]

PORT 10,0,1,4,206,183
530 Only client IP address allowed for PORT command.
Hope this helps.

[JD]

Hey that's cool of you. Thanks!

Thanks for the transcript. I noticed the PORT problem also, but it's not an invalid command or usage of it, just simply that you're behind a router/firewall and the IP address is therefore a private one. Try using Yummy's new 'Active IP address' option in the Server Option tab of the Preferences, entering your real IP address.

The PORT (active FTP) method is being tried automatically by Yummy because Serv-U is rejecting some connection attempts, so Yummy is trying to reverse the Passive FTP (standard) method of connection to see if it is more successful.

I'm still investigating this, so I'll post my conclusion later, but for now, if the 'Active IP address' option doesn't fix the problem, try disabling the 'Auto-detect Passive/Active mode FTP' checkbox in the Server Options tab of the Preferences and see if it makes any difference.

-Jason

[JD]

To follow up on this, after extensive testing, I have to conclude that there is actually some kind of bug in the Serv-U implementation of FTPS:

I've tested Yummy with Serv-U and can repeat the problem consistently, but can find nothing wrong with what Yummy is doing.

I've tested Yummy with several other PC FTP servers that support SSL (for example, GloablScape FTP Server and WS_FTP server) and everything worked perfectly, even after thousands of file transfers.

It seems to be the multiple simlutaneous transfers that is causing Serv-U to get confused. For example, if you disable the 'Split transfers' option in the Transfers tab of the Preferences, everything is just fine.

I know all this sounds like a cop out... but the evidence is undeniable

[JD]

Solved!

With the extraordinarily kind help of those wonderful people at RhinoSoft (http://www.rhinosoft.com) - Mark P. Peterson (Founder & President) and Louis C. Branch (Technical Support) - working together to narrow down the problem over several days of testing, we finally discovered the bug... yes, it was my fault all along!

Thank you for everything, guys!!

One interesting discovery from of all this is that the problem in Yummy was actually happening with all the PC FTP servers I tried, but not one of them flagged it up as an error - and boy it certainly was a nasty error. It just goes to prove that Serv-U is a totally 100% pure quality product. Not only was it the fastest server of all those I tested with by a long shot, this episode shows that I can trust it, and for a secure server solution that is essential. I tip my hat to the developers of such fine software!

So, I'll be releasing a 1.5.3 update as soon as the beta testers have given it the thumbs up.

Thanks for your patience!

[mfichtner]

Thanks for the follow-up(s), Jason -- and for solving the problem!