Sungju's Slow Life

Personal journal

Problems of TCP RST at the improper position.

Recently, I had to solve the problems which got too much unclosed TCP connection on the server.

During digging into this problem, one of my colleague found very good and useful information which is related to the IE.

Title : “Internet Explorer and TCP RST – a reason to dislike”.

I found that IE was using keepalives, but when I closed the window while the connection was still alive, it sent a RST rather than a FIN. IE also sent a RST in a number of other conditions such as stopping a page loading, linking to another page etc, although not in an overly obvious pattern (the pattern is there, I just didn’t spend a long time figuring it out). This seemed odd, so I perused the RFC for TCP/IP. It quite clearly indicates, repeatedly, that a RST is to be used when the connection gets out of sync (e.g. duplicate SYNS, or other anomalies).

You can find original contents from

Very unpleasant behavior but what should I do if customer couldn’t change there browser. Sad story.

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