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IE vs firefox, 6 tcp fin ack retransmissions and then rst?


Hello, I have two conversations that are made with two browsers IE 11 and Firefox. The IE 11 conversation ends in a weird way, trying to send FIN ACK, but never receives a response, and then eventually resets.

This does not happen when I am using Firefox browser to the same webserver.

asked 26 Nov '15, 02:26

OlofL's gravatar image

accept rate: 0%

edited 26 Nov '15, 02:28

One Answer:


In the firefox case the server closes the session 5 seconds after the HTTP reply was sent. Firefox immediately issues a close and the FIN gets sent out and ACKed immediately.

In the IE case it takes 81 seconds for the client to send its FIN In the meantime the server has already closed the socket so you don't get an ACK to your FIN .

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answered 26 Nov '15, 08:36

mrEEde's gravatar image

accept rate: 20%

Yeah is this normal behaviour? We are getting loads of invalid hits in our firewall.

(26 Nov '15, 23:08) OlofL

sure it is not, but you have to claim it with Microsoft.

(27 Nov '15, 01:27) sindy