11-02-2023 05:07 AM - edited 11-22-2023 05:17 AM
Dear all,
while debugging SMTP-Authentication-Problems I notice the following strange behaviour:
connecting with "openssl s_client -connect server.name:587 -starttls smtp"
Trying username "Anton" (Base64 = QW50b24=)
---------------
AUTH LOGIN
334 VXNlcm5hbWU6
QW50b24=
DONE
---------------
-> ESA closes connection unexpectedly
Trying Username "A" (QQ==)
--------------------------
auth login
334 VXNlcm5hbWU6
QQ==
DONE
--------------------------
Same error (unexpected close) as above
Trying username "D" (RA==)
--------------------------
auth login
334 VXNlcm5hbWU6
RA==
334 UGFzc3dvcmQ6
RA==
535 #5.7.0 Authentication failed
--------------------------
-> That's the expected behaviour, as the user does not exist
Further tests show, that usernames beginning with (@,A,B,C) giving an encoded Base64-String starting with "Q" lead to the same erroneous behaviour.
The same happens, when trying to authenticate with a password starting in cleartext with (@,A,B,C)
Any idea?
Thanks,
Harald
11-21-2023 09:54 PM
Hey Hallowelt,
As this seems to be a specific problem with you environment, I will suggest you to open a TAC case with Cisco and the team will help you resolve it.
Adding the methods to open a case(You can use any one of them):
1. Go to the TAC website > My support > Open/View Cases > Open New Case ;
2. Send an email to tac@cisco.com and make sure you include your CCO login;
3. Call them;
Regards
Stuti Kandpal
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