WIZnet Developer Forum

W5100s TCP Server SYN response

The W5100s’s response to a SYN message has both the ACK and RST flags set.

What is causing the reset flag to be set in the ACK?
Thanks.
Giri

Because it can not accept the SYN request. Most probably you reuse port number from previous communication, and W5100s thinks that it is continuation of the closed connection. You must use another source port number at the sender side.

Thanks for the response.

I am only starting to play with the w5100s, so it is its basic testing.

And here it is the first connect request after power cycle of the wiznet module.

Show the related packets / share Wireshark log.

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Eugenyhttps://nam05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fforum.wiznet.io%2Fu%2Feugeny&data=02|01|giri.ramaswamy%40conduent.com|9b24773a635d402cf31808d6fa3306a1|1aed4588b8ce43a8a775989538fd30d8|0|0|636971494391207387&sdata=9oGWTzJm2IJ2pOVSG822duMgYaCbZ7s8TuS4sTloEL8%3D&reserved=0 Great Contributor
June 26

Show the related packets / share Wireshark log.

image001.jpg

(Attachment Wiz810sio_SynReset.pcapng is missing)

MAC 00:50:B6:26:23:45 is the WizNet Module (@ IP 192.168.0.48)

image001.jpg

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Eugenyhttps://nam05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fforum.wiznet.io%2Fu%2Feugeny&data=02|01|giri.ramaswamy%40conduent.com|9b24773a635d402cf31808d6fa3306a1|1aed4588b8ce43a8a775989538fd30d8|0|0|636971494391207387&sdata=9oGWTzJm2IJ2pOVSG822duMgYaCbZ7s8TuS4sTloEL8%3D&reserved=0 Great Contributor
June 26

Show the related packets / share Wireshark log.

image001.jpg

Wiz810sio_SynReset.zip (1 KB)

Does the W5100s listen on the port 5000 with at least one socket?

I only have 1 socket.
The SR(0) is at 0x14 -> Sock_LIsten.

Eugeny:
I am not sure what I did - yet, But I have socket connection.
I think the only thing I did was added a delay between SR(0) reads.
Will debug some more, but wanted to let you know the updated status.
Very much appreciate your Cpu cycles.
Giri