Can't contact LDAP server

darootler

Well, i just reviewed the logs again and every time the ldap server resets the connection and an authentication is made i am getting this error. False username/password isn’t the case because the credentials are stored and not entered manually. I am sure that has something to do with the changes mentioned above, could you be so kind and contact Jan Engelhardt for a quick review of my findings?

Otherwise i have to downgrade kopano, and that’s hard like hell with all the dependencies.

Regards
Richard

darootler

Even more debug information:

Kopano logs:

Aug  4 17:37:29 serverv2 kopano-server[1330]: Authentication by plugin failed for user "USERNAME": LDAP auth for user "USERNAME": Can't contact LDAP server
Aug  4 17:37:31 serverv2 kopano-server[1330]: Authentication by plugin failed for user "USERNAME": LDAP auth for user "USERNAME": Can't contact LDAP server

tcpdump from kopano lookup:

17:37:29.128581 IP kopano-server.49129 > ldap-server.domain: 61640+ AAAA? kopano-server. (42)
17:37:29.128806 IP ldap-server.shell > kopano-server.46178: Flags [.], ack 2058, win 9434, options [nop,nop,TS val 3865952505 ecr 2989291037], length 0
17:37:29.129298 IP ldap-server.domain > kopano-server.49129: 61640* 0/1/1 (177)
17:37:29.129652 IP kopano-server.57704 > ldap-server.domain: 47351+ AAAA? kopano-server. (26)
17:37:29.130077 IP ldap-server.domain > kopano-server.57704: 47351 0/0/1 (37)
17:37:29.130528 IP kopano-server.56223 > ldap-server.domain: 54523+ AAAA? kopano-server. (42)
17:37:29.130994 IP ldap-server.domain > kopano-server.56223: 54523* 0/1/1 (177)
17:37:29.131039 IP kopano-server.39715 > ldap-server.domain: 34035+ AAAA? kopano-server.my.domain. (58)
17:37:29.131504 IP ldap-server.domain > kopano-server.39715: 34035 NXDomain* 0/0/0 (58)

tcpdump from shell nslookup:

17:41:46.072987 IP kopano-server.57054 > ldap-server.domain: 53018+ A? kopano-server. (42)
17:41:46.073725 IP ldap-server.domain > kopano-server.57054: 53018* 1/1/1 A 192.168.2.3 (217)
17:41:46.073877 IP kopano-server.55171 > ldap-server.domain: 25675+ AAAA? kopano-server. (42)
17:41:46.074676 IP ldap-server.domain > kopano-server.55171: 25675* 0/1/1 (177)

My DNS server cannot answer the AAAA request because i am not using IPv6. On the kopano server i have disabled IPv6 on grub level. So why is kopano trying to resolve the name of the LDAP server via IPv6 lookups?

Maybe that’s the cause of this issue.

Regards
Richard

jengelh

So why is kopano trying to resolve the name of the LDAP server via IPv6 lookups?

First, that’s glibc, second, because the content of data transmissions and castrating a system’s ability to offer AF_INET6 sockets are two separate things. It helps to know what ipv6.disable does, and more importantly, doesn’t do.

darootler

@jengelh said in Can't contact LDAP server:

So why is kopano trying to resolve the name of the LDAP server via IPv6 lookups?

First, that’s glibc, second, because the content of data transmissions and castrating a system’s ability to offer AF_INET6 sockets are two separate things. It helps to know what ipv6.disable does, and more importantly, doesn’t do.

Thank you for clarification, i think i fixed all my DNS issues playing around with systemd-resolve but i am still facing issues with kopano-server authentication issues after upgrading to 10.0.6.356:

ldap_connect            Number of connections made to LDAP server                                       27
ldap_reconnect          Number of re-connections made to LDAP server                                    0
ldap_connect_fail       Number of failed connections made to LDAP server                                0
ldap_connect_time       Total duration (µs) of connections made to LDAP server                          953515
ldap_max_connect        Longest connection time (µs) made to LDAP server                                54989
ldap_auth               Number of LDAP authentications                                                  129
ldap_auth_fail          Number of failed authentications                                                10
ldap_auth_time          Total authentication time (µs)                                                  3188436
ldap_max_auth           Longest duration (µs) of authentication made to LDAP server                     58361
ldap_avg_auth           Average duration (µs) of authentication made to LDAP server                     24737
ldap_search             Number of searches made to LDAP server                                          457
ldap_search_fail        Number of failed searches made to LDAP server                                   0
ldap_search_time        Total duration (µs) of LDAP searches                                            426920
ldap_max_search         Longest duration (µs) of LDAP search                                            2977
userplugin              User backend plugin                                                             ldap

Any hints?

Regards
Richard

jengelh

A pull request is under review.

darootler

After investing about 2 days i just downgraded to version 10.0.6.13.

Regards
Richard

darootler

Any updates here?

Regards
Richard

jengelh

included in >= 10.0.6.428.

alexthetiger68

I am on Kopano Core Version core-10.0.6.406.e263d46-Debian_10-amd64 and experience the same ldap issue since the upgrade with the ldap service running on Univention UCS.

    osrelease               Pretty operating system name                                                    Debian GNU/Linux 10 (buster)
    program_name            Program name                                                                    kopano-server
    program_version         Program version                                                                 10.0.6
    server_guid                                                                                             7636E72C7285493384B2CCC3487C6508

Interesting enough, under https://download.kopano.io/community/core%3A/ I find only the 10.0.6.406 Version since 13.08.2020. I thought these artefacts were built daily? Anyway, when do you expect version 428+ with the ldap fix to be available?

Should you require more information to debug the issue, I’m happy to assist.

alexthetiger68

@jengelh said in Can't contact LDAP server:

included in >= 10.0.6.428.

Does anyone know when this, or a later, version will be available on https://download.kopano.io/community/core%3A/ ? There has been no update on the nightly builds since 13.08.2020. Or can anyone point me to the correct repo to compile it myself?

fbartels

@alexthetiger68 said in Can't contact LDAP server:

Or can anyone point me to the correct repo to compile it myself?

The sources for the Groupware Core part are located at https://stash.kopano.io/projects/KC/repos/kopanocore/browse

The last I checked the missing nightly releases were looked into, but currently the focus is on finalizing the upcoming release for customers, so the nightly downloads are not the highest priority.

alexthetiger68

Good news, everyone.

I just upgraded to core-10.0.6.496 and so far, the ldap connection errors seems to be gone.

alexthetiger68

Well, the error messages have changed slightly, but at least the clients (Outlook via Activesync w/o KOE, Mail on iOS) do not seem to complain anymore.

Previously the clients would show a popup stating that the username/password was wrong, which I just had to <cancel> multiple times till it went away and synching of Kopano server to the clients resumed.

The new error message:
2020-10-08T06:39:27.011248: [error ] Previous message logged 76 times
2020-10-08T06:39:27.011824: [error ] K-1585: LDAP auth error: Can’t contact LDAP server. Will rebind & retry.
2020-10-08T06:39:27.065428: [error ] K-1582: LDAP search error: Can’t contact LDAP server. Will reconnect and retry.