I know there is no answer to this, perhaps someone can offer something we haven't looked at.
The problem: One client has three servers, each with their own IP, Linux/Apache, I do not have versions but it was moved just last year so they're all fairly new. The servers are web server, data server, mail server. I have access to all three via SSH/FTP.
Intermittently, when making an FTP connection to any of these servers, it connects, authenticates, gets to LIST . . . . and hangs until timeout.
The problem first appeared moving to a new ISP. When they first moved, I was on a different satellite provider and changed over, and the problem persists.
JUST my connection, and only to this server. See below.
My Environment: Win XP Pro, NetWork Everywhere 4 port router, Wild Blue satellite internet, pro plan. All updates current, AVG functioning. With and without Windows firewall on (appears to have no effect one way or the other.)
Server environment: This is a reputable Portland ISP catering to dedicated server racks only, not shared hosting, and it's costing him a mint. I don't know that I can give any more details than that, it's not economy hosting. There are no bandwidth, email, or other limitations. His hardware is fairly new, I don't know specs, but as said it was just last year and is easily far above and beyond his needs in terms of disk space, memory, and other hardware.
What I've Tried:
First off is to see if "it's me." When it crops up, the first thing I do is have someone at some other point of entry try to FTP to these servers. My admin in a different city, etc., is able to log in and FTP without issue, so this initially points to "my" setup as the problem.
When this comes up - and it IS intermittent - I immediately connect to other customer's servers. One on the east coast, one in Arizona, one on Australia - no problems, connects right up and lists directory. In fact, my current workaround is to FTP files to my server, then SSH to his server, and get the files off my server via ftp from his. (Is that insane or what?)
FTP Client - I've tried 6 or 8 of them, including command line FTP via DOS/Windows. SFTP, non-secure FTP, all the same results. Connect, LIST . . . . hang.
Router/computer issues: shut down comp., reboot router, leaving it off for 30 seconds, start router, start comp. In one of the many attempts to debug, this appeared to "fix" it, but tonight I went through the same thing and it didn't, so it's starting to look like it's not the router or computer.
FTP account problem: we've created new FTP accounts and I've attempted to use these in the "problem times." Same result.
Admin has scrubbed the server for any indications something may be blocking me specifically by IP or anything, finds nothing.
Note that it's not just one box - when the problem arises, I can't connect to any of the boxes in his quarter-rack.
Caveat: there *IS a firewall on this server, and I do not log on to it. I don't know how this works, but have asked admin to look at it, and the host says it's passing through my connection without restriction.
When the problem goes away, I can connect to all of them.
The timing is random, it can occur at "peak times" or at 3 AM.
SSH is not a problem, as mentioned, when I get into these "problem times" I SSH in and work around the fence.
Support cries "nothing wrong." Admin cries "nothing wrong." Client cries "nothing wrong" (even he can FTP to his sites without problem.
I've even considered the paranoid, that some developer has installed something to make it impossible to work (many hands have been in this pie.) Who knows. Just because I'm paranoid doesn't mean they aren't after me. :-)
So here I am, out on Mars, with no solutions. I'm about to walk away from this customer based on the fact that I simply can't get any work done because a two second process - FTP it up and be done - is now a black hole that can eat up hours of my time.
Thanks for reading, and any ideas you might have.