Howdy Simon, Also, if the client initiates the close of the connection the port can be reused right away.
Regards, Roger -----Original Message----- From: [email protected] <[email protected]> On Behalf Of Roger Cover via lwip-users Sent: Tuesday, November 4, 2025 8:40 AM To: Simon Goldschmidt <[email protected]>; Mailing list for lwIP users <[email protected]> Cc: Roger Cover <[email protected]> Subject: Re: [lwip-users] Bug in TCP connect Howdy Simon, I am using the Chrome browser. Regards, Roger -----Original Message----- From: Simon Goldschmidt <[email protected]> Sent: Tuesday, November 4, 2025 8:38 AM To: Mailing list for lwIP users <[email protected]> Cc: Roger Cover <[email protected]> Subject: Re: [lwip-users] Bug in TCP connect [You don't often get email from [email protected]. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] Hi Roger, as far as I know, this is just expected TCP behaviour (lwIP keeps the connection around in TIME_WAIT state). Which client are you using that reuses its port too fast? Regards, Simon On 11/4/2025 4:28 PM, Roger Cover via lwip-users wrote: > Greetings, > > There is a bug in the TCP connect logic that is exposed by the following: > > 1. The lwIP device implements a web server. > > 2. An ephemeral port on a client is used to download a file from the > lwIP device. Closing this connection is initiated by the lwIP device. > > 3. Within 24 seconds, client uses the same ephemeral port in an attempt > to open another connection. This attempt fails (if the attempt is made > after more than 24 seconds it succeeds). > > The failure is demonstrated by the SYN packet from the client being > answered by a packet without SYN (only ACK). The client retries and > eventually times out. > > Here is a screen shot of WireShark showing the failure: > > I have many hours of captured data showing the failure at various times. > For reasons not known to me, the failure is more likely to occur using > the Chrome browser on Windows 11. > > Regards, > > Roger W. Cover > > 520-614-9027 > > Spectral Instruments, Inc. > > 420 N. Bonita Ave. > > Tucson, AZ 85745 > > > _______________________________________________ > lwip-users mailing list > [email protected] > https://lists.nongnu.org/mailman/listinfo/lwip-users _______________________________________________ lwip-users mailing list [email protected] https://lists.nongnu.org/mailman/listinfo/lwip-users _______________________________________________ lwip-users mailing list [email protected] https://lists.nongnu.org/mailman/listinfo/lwip-users
