Oct 14, 2006

Getting FTP To Work In Windows XP SP2!

Getting FTP Working in Windows XP

Before Windows SP2 (Service Pack 2) FTP (File Transfer Protocol) worked. I used it everyday with my favourite FTP program, Filezilla ( Then SP2 came along and FTP stopped working. I searched and searched internet wide for a solution and tried them all, including disabling my anti-virus software and the Windows Firewall, but eventually I gave up and used an internet based file transfer application which was not ideal and inferior to using FileZilla. But today I decided once again to get FTP working with Windows XP SP2. Victory!

I noticed that when FTP stopped working with FileZilla events appeared in the "Event Viewer" (Control Panel/Administrative Tools/Event Viewer/System/) in Windows. I did some searching for "EventID 4226". Then came accross a fix!

The problem is that before Windows XP SP2 the limit on half-open connections (SYN) was 65,535 then SP2 introduced a limit of 10. This is what has been causing my problems with FTP and FileZilla in Windows XP SP2 and why pre SP2 FTP worked and post SP2 FTP didn't work. So I applied a patch from LVLLord which replaced the "TCPIP.SYS" file that SP2 changed. The fix uses MSDOS and fixes the problem by allowing the limit on SYN connections to be set to any number of connectons. I set the limit to 100. I then restarted FileZilla and everything started working like it was 2001!

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