# LDAP connection: Fatal: Couldn't connect to auth socket

**URL:** <https://discourse.mailinabox.email/t/ldap-connection-fatal-couldnt-connect-to-auth-socket/16118>\
**Category:** Help with Setup/Upgrade\
**Created:** [November 13, 2025, 9:33am UTC](https://discourse.mailinabox.email/t/ldap-connection-fatal-couldnt-connect-to-auth-socket/16118 "2025-11-13T09:33:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![stta](https://discourse.mailinabox.email/letter_avatar_proxy/v4/letter/s/edb3f5/32.png) [@stta](https://discourse.mailinabox.email/u/stta)\
**Post date:** [November 13, 2025, 9:33am UTC](https://discourse.mailinabox.email/t/ldap-connection-fatal-couldnt-connect-to-auth-socket/16118/1 "2025-11-13T09:33:03Z")

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Hello,  
first, I want to say thank you that I can join to this forum.

I’m trying to establish an LDAPS connection to my Active Directory and use AD authentication for Roundcube. The reason is that I want to replace MS Exchange.

Has anyone successfully got this combination working?

Certificates have been created and installed.

`openssl s_client -connect server.local:636 -showcerts -brief </dev/null`

→ “Verification: OK”

The test also works with:

```auto
ldapsearch -x -H ldaps://server.local \

-D "cn=ldapread,cn=Users,dc=domain,dc=local" -W \
-b "dc=domain,dc=local" \
"(objectClass=user)" sAMAccountName

```

However, I can’t get Dovecote to work with Roundcube so that the AD credentials work.

I get the following error message with every test:

`sudo doveadm auth test -a /var/run/dovecot/auth-client 'mail@domain.local' 'SECRET'`  
 → Fatal: Couldn’t connect to auth socket

To my knowledge, `dovecot-ldap.conf.ext`, `/etc/dovecot/conf.d/10-auth.conf`, and `/etc/dovecot/conf.d/10-master.conf` are configured correctly.

Any ideas would be appreciated.

Regards,  
Steffen

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<div class="post-metadata">

**Author:** ![system](https://discourse.mailinabox.email/uploads/default/original/2X/4/4d0933d13c456b7e57f296aa6cc344525b6f0c70.png) [@system](https://discourse.mailinabox.email/u/system)\
**Post date:** [November 20, 2025, 9:33am UTC](https://discourse.mailinabox.email/t/ldap-connection-fatal-couldnt-connect-to-auth-socket/16118/2 "2025-11-20T09:33:24Z")

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