SASL: encoded packet size too big

[Eugene]

The error message origins from cyrus-sasl sources.
https://github.com/cyrusimap/cyrus-sasl/blob/352b3e66c3712fddc622ee850c3537457ffffc20/common/plugin_common.c#L667

The strange thing is that dovecot is the only sufferer.

Filter `tcp.payload contains "\x30\x81\xac\x02"` shows that part of the AP-REP is interpreted as packet length.
I will ask cyrus-sasl project for further help.

Sorry for the hassles.

On 8/15/19 4:14 PM, Eugene via dovecot wrote:
> I see nothing suspicious in FreeIPA slapd logs because connection drops before SASL negotiation completion. 
> Network analysis shows client sending RST after receiving `bindResponse(7) saslBindInProgress`.
> 
> On 8/15/19 3:07 PM, Aki Tuomi via dovecot wrote:
>> I suspect the problem is that dovecot tries to report LDAP error over GSSAPI. So the best fix is to make sure your LDAP server does not return error. =)
>>
>> Aki
>>
>> On 15.8.2019 14.56, Eugene Bright wrote:
>>> That's right.
>>> GSS-API is not used anywhere else.
>>> Do you like to inspect my full configuration?
>>> I can dump connection session and send pcap file here.
>>>
>>> On August 15, 2019 7:27:20 AM GMT+03:00, Aki Tuomi <aki.tuomi at open-xchange.com> wrote:
>>>
>>>         On 15/08/2019 00:34 Eugene via dovecot <dovecot at dovecot.org> wrote: The next combination of parameters makes 100% LDAP connections unsuccessful (the log snippet form the previous mail). sasl_bind = yes sasl_mech = gssapi tls = yes Looks like this combination is utterly incorrect and should be prohibited (tls must not be used when mech is gssapi). https://lists.fedorahosted.org/archives/list/sssd-users@lists.fedorahosted.org/message/G7S2TOFDCM62ZUHIBWYVZIEVYXO3KYAI/ With `tls = no` errors `encoded packet size too big` becomes sporadic, but still heart auth orepations performance. May be there are two different problems. 
>>>
>>>
>>>     Does the "encoded packet size too big" coincide with LDAP server connection failure?
>>>
>>>     Aki
>>>
>>>         Has someone encountered this problem before? How can I help to facilitate the issue debugging? [I] net-mail/dovecot Installed versions: 2.3.7.1(01:58:12 08/14/19)(bzip2 caps ipv6 kerberos ldap libressl lua lz4 lzma pam postgres sieve sqlite tcpd zlib -argon2 -doc -lucene -managesieve -mysql -selinux -solr -static-libs -suid -textcat -vpopmail) On 8/15/19 12:01 AM, Eugene wrote:
>>>
>>>             Hello! Dovecot uses it's own SASL implementation, doesn't it? Aug 14 23:45:23 example.com auth[10428]: GSSAPI client step 1 Aug 14 23:45:23 example.com auth[10428]: encoded packet size too big (813804546 > 65536) Aug 14 23:45:23 example.com dovecot[10085]: auth-worker(10428): Error: LDAP: Can't connect to server: ldap://ipa2.example.com Aug 14 23:45:23 example.com dovecot[10085]: auth: Error: auth worker: Aborted USER request for eugene: Lookup timed out Aug 14 23:45:23 example.com dovecot[10085]: imap: Error: auth-master: login: request [3847225345]: Login auth request failed: Internal auth failure (auth connected 60000 msecs ago, request took 60000 msecs, client-pid=10362 client-id=1) Looks like cyrus-sasl encountered same problem earlier. https://lists.andrew.cmu.edu/pipermail/cyrus-sasl/2017-March/003001.html I never have such an issue with ldapsearch. So, I assume there is a similar problem in Dovecot SASL implementation. 
>>>
>>>         -- Eugene Bright IT engineer Tel: + 79257289622 
>>>
>>> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>>> Eugene Bright
>>> IT-engineer
>>> Tel.: +7 925 728 96 22
>>
> 

-- 
Eugene Bright
IT engineer
Tel: + 79257289622

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