Date: Tue, 30 Oct 2001 18:14:01 -0600 (CST) From: Ryan Thompson <ryan@sasknow.com> To: Mail Administration <mail@twwells.com> Cc: questions@FreeBSD.ORG Subject: Re: ftp hanging at transfer end Message-ID: <Pine.BSF.4.21.0110301805370.43207-100000@ren.sasknow.com> In-Reply-To: <E15yi2X-000EB3-00@server.twwells.com>
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Mail Administration wrote to questions@FreeBSD.ORG: > I've got a 4.3 server that is being used for outgoing FTP transfers. > FTP sessions fairly frequently hang after transferring a file. > > The client is a Windows FTP client. Which Windows does not seem to > make any difference. However, some FTP clients fail and others do not. > The problem does not occur when the client is Unix. The originating > network does not seem to make any difference. A packet sniff on the > Unix side says that a FIN packet is sent at the end of the transfer > but the Unix side does not see a FIN from the client. > > This is an intermittent problem; it generally manifests when > transferring multiple files, the transfer stops after a few files. Is it possible that the transfer stops after LARGE files? FTP maintains two separate connections for each client.. a control and a data connection. A separate data connection is opened for each item transferred. The trouble is, in many cases, the control connection stays idle for the entire duration of the data transfer. So, if the data transfer takes a really long time, the connection could time out of a lot of things (connection stacks, stateful firewalls, proxies, etc). This would explain why it seems intermittent. Maybe this isn't what's happening in your case, but maybe it's worth a look. You've run tcpdump.. what happens with the control connection during a long transfer (where 1 transfer = 1 file)? Is anything being sent while the transfer is occurring? What happens after? Anything? Hope this helps, - Ryan > Any ideas what might be causing the problem? > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message > -- Ryan Thompson <ryan@sasknow.com> Network Administrator, Accounts SaskNow Technologies - http://www.sasknow.com #106-380 3120 8th St E - Saskatoon, SK - S7H 0W2 Tel: 306-664-3600 Fax: 306-664-1161 Saskatoon Toll-Free: 877-727-5669 (877-SASKNOW) North America To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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