Hi there, I'm trying to debug a TCP problem and I've rather run out of ideas, I was wondering if anyone might be able to help me... The problem I'm seeing relates to re-use of port/IP address combinations. I'm connecting from port 12345 to Linux/lighttpd on port 80. I do an HTTP/1.0 request, the server sends me some data, then a FIN/ACK. I ACK that, then send my own FIN/ACK. The connection goes away for me, and goes to TIME_WAIT on the server. If I try to reuse the the IP/port combination, normally everything works fine, as lighttpd appears to use SO_REUSEADDR. Sometimes, however, things do not go so well - I send a SYN to initiate a new connection, and Linux/lighttpd responds by re-sending the final ACK - I think I'm doing something wrong with either the teardown of the old socket, or the SYN of the new connection which is causing Linux/lighttpd to think the SYN is somehow part of the old connection, so it retransmits the ACK as a reminder that the old conversation is over. I respond with a RST, back off for three seconds, then try again and connect OK. I'm mystified by the retransmitted ACK though - can anyone explain what I'm doing wrong? A capture is attached, taken on the Linux/lighttpd server. Thanks, Peter
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mystery_ack.pcap
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