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Ethernet Frame Check Sequence Incorrect

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Hi All, I am trying to connect to exchange server 2013 using IMAP in C# code and the code is failing to authenticate the user. So I am debugging using wireshark to check where exactly the problem occurs. From the wireshark trace I see "Ethernet Frame Check Sequence Incorrect" for all my IMAP request whereas this error is not seen when I connect to exchange server 2010. So I am not sure what could be the problem with exchange server 2013 machine. Please help to resolve this issue.

Thank you,

asked 18 Feb '15, 02:26

SSK's gravatar image

SSK
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Exactly where do you capture in each instance?

(18 Feb '15, 06:13) Jaap ♦

I am capturing this on my exchange server machine

(19 Feb '15, 00:54) SSK

and the code is failing to authenticate the user.

Does that mean you are able to establish a TCP connection and then you get an error message while you are authenticating the user?

(23 Feb '15, 09:54) Kurt Knochner ♦

Yes you are correct. And also this happens not all the time few times authentication is failed and then it is working for few more times then fails. I couldn't find any specific pattern in which authentication fails.

(24 Feb '15, 00:57) SSK

One Answer:

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As a follow-up to you comment: the FCS errors have no meaning if you are able to establish a TCP connection. They are probably just the result of your capture setup.

To figure out why the server does not accept the user credentials, you could also look at the IMAP error code, but I guess you've done that already.

A better approach would be to active some sort of debugging on the target server (Exchange).

Regards
Kurt

answered 24 Feb '15, 01:47

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Kurt Knochner ♦
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accept rate: 15%