I'm hosting a bunch of jpg/gif files, to inject into posts made on other boards, on my home server, using vsftpd.

In most cases, this appears to be working fine. But, for some particular users, when they open a post, it doesn't display the image.

Looking at my transfer logs, I can see the connection. However, most of the transfers are failing after exactly 35040 bytes, which is the default TCP Window Size. They all are using IE, but I'm not sure which version(s).

I've tried it myself, from all the remote systems I have access to, and it always works. I've varied the IE Settings for FTP to both Active and Passive, but I can't get it to fail.

Here's one of the relevant lines from the vsftpd.log:

Tue Apr 29 09:43:22 2008 1 xx.xxx.xxx.xx 35040 /testthis/Tuesday.gif b _ o a IEUser@ ftp 0 * i

Next, I tried tcpdump, on the control port, which shows this error:

426 Failure writing network stream

Which WireShark interprets as:

Response code: Connection closed; transfer aborted (426)
Response arg: Failure writing network stream.

Adding the data ports to tcpdump doesn't really add any further clues, apart from the last transmission from the client is an [RST, ACK], which prompts the 426 error.

Any thoughts on what's going on here.

Cheers,
Eddie