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FTP passive mode - a sometimes cure for upload hangs

Archive - Originally posted on "The Horse's Mouth" - 2008-09-20 12:06:37 - Graham Ellis

Are you on the road (as I am today) and having trouble FTPing files up to your server (as I was today)? Symptom - the connection sets up just fine, it's great when you're looking for files, but as soon as you put an upload / download instruction in, it hangs ...

I've switched passive mode off ... that's
passive off
in my standard ftp client, and it's now working fine.

The FTP protocols are quite complex and have a number of options - the setup is designed to get a good throughput even between distant server and client. A traditional "acknowledgement before the next block is sent (TCP) protocol" - would be simpler, but would add a round trip pause at each block acknowledgement, so an extra (UDP) channel is used. And just occasionally, this causes a few issues!

Last night, we swung into Carlisle, PA - not to be confused with Carlisle, England - after dark, and here's a picture taken both to show the type of area that it is (just one photo says a lot) and to show you my tip above in action.


We're in town for Lisa'a 35 year high school reunion ... and a first group met up last night at the new All Star bar on South West Street (which should not be confused with West South Street, which the town also boasts). Link - class site (which Lisa looks after ;-) )

I have been to Carlisle before and it's a lovely and friendly town. Although it's midday in the UK as I write this, it's just 7 a.m. here and we've got a chance to see the place, soak the atmosphere, and for Lisa to relive some of her times today and tomorrow morning. I expect she'll be looking at this picture and saying "that's xxxx" or "look at yyyy" as and when she gets to this article. I myself can already put a few names to faces, but I'm not into the class politics, so I could so easily leave someone out and cause offence. I say with Ben (name changed) last night - married to one of the class and acting rather like a fish out of water (probably how he felt too) and felt very sorry for him; not the world's greatest conversationalist, nor with the ability (or perhaps desire) to set up a two way street and ask questions in return, we eventually hit on the subject of where the economy is going ... and he brightened up considerably as he promoted doom and gloom, and spoke of how he and his wife, now both retired, do important volunteer work providing food for down and out people who would otherwise starve ... in Delaware.