The first time a user signs in with LDAP credentials, GitLab will create a new GitLab user associated with the LDAP Distinguished Name (DN) of the LDAP user.
To enable GitLab LDAP integration you need to add your LDAP server settings in `/etc/gitlab/gitlab.rb` or `/home/git/gitlab/config/gitlab.yml`.
In GitLab Enterprise Edition you can have multiple LDAP servers connected to one GitLab server.
Please note that before version 7.4, GitLab used a different syntax for configuring LDAP integration.
The old LDAP integration syntax still works in GitLab 7.4.
If your `gitlab.rb` or `gitlab.yml` file contains LDAP settings in both the old syntax and the new syntax, only the __old__ syntax will be used by GitLab.
If you are getting 'Connection Refused' errors when trying to connect to the LDAP server please double-check the LDAP `port` and `method` settings used by GitLab.
Common combinations are `method: 'plain'` and `port: 389`, OR `method: 'ssl'` and `port: 636`.
## Enabling LDAP sign-in for existing GitLab users
When a user signs in to GitLab with LDAP for the first time, and their LDAP email address is the primary email address of an existing GitLab user, then the LDAP DN will be associated with the existing user.
If the LDAP email attribute is not found in GitLab's database, a new user is created.
In other words, if an existing GitLab user wants to enable LDAP sign-in for themselves, they should check that their GitLab email address matches their LDAP email address, and then sign into GitLab via their LDAP credentials.
If multiple LDAP email attributes are present, e.g. `mail: foo@bar.com` and `email: foo@example.com`, then the first attribute found wins -- in this case `foo@bar.com`.