TCP Connection Limits

October 1, 2009 at 3:10 pm | Posted in Computers, Internet, Security, Software | Leave a comment

During some recent system maintenance, I noticed regular 4226 errors in Event Viewer, System. (right click My Computer and select Manage)

It states: “TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts.” It turns out that SP2 of Windows XP introduced a new limit in an apparent effort to improve security. (Apparently, they don’t do this in  Windows 7)

The only problem is, it also reduces some of the benefit of your Internet connection speed you’re paying for, especially for large files and a download manager or P2P program.

If you search for error 4226, you get instructions for how to terminate programs overusing connections or failing to connect.

The “malware” doing this on my computer was Firefox and my AV software, things I expect to connect. And things being delayed in their ability to connect.

As this site observes, it’s a rather meaningless gesture as even the 10 connection limit can infect thousands of systems in a minute.

Fixing the issue is not something simple like changing a form setting or even a registry entry. It requires changing a hex value the above link mentions. Unless you have a hex editor and know what you’re doing, not a good idea.

I ran into a couple of tools that will quickly do the fix for XP SP3. I used TCPIP Patcher. It’s for for SP2 & 3, it backs up the old sys file and allows you to undo the change.

The SP2 setting is 10, down from what I understand was 50. Some suggest kicking it up to 50 is fine. This tool suggests 256+ and another site suggests 5-600. Unless you have a seriously large pipeline and do a lot of downloading, you’ll probably find something more modest fine. It’s easy to adjust.

Check out SpeedGuides other tweaks for speeding your connection. Of note is the downloads page, offering you a graphical interface to work with the many obscure settings that underlie TCP/IP.

Happy Surfing!

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