> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/33669) in GitLab 12.6,
if a user has a pre-existing username and password, they can still use that to log
in by default. However, this can be disabled.
GitLab supports authentication using smartcards.
## Existing password authentication
> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/33669) in GitLab 12.6.
By default, existing users can continue to log in with a username and password when smartcard
authentication is enabled.
To force existing users to use only smartcard authentication,
[disable username and password authentication](../../user/admin_area/settings/sign_in_restrictions.md#password-authentication-enabled).
## Authentication methods
GitLab supports two authentication methods:
...
...
@@ -88,10 +94,7 @@ Certificate:
### Authentication against an LDAP server
> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/7693) in
[GitLab Premium](https://about.gitlab.com/pricing/) 11.8 as an experimental
feature. Smartcard authentication against an LDAP server may change or be
removed completely in future releases.
> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/7693) in [GitLab Premium](https://about.gitlab.com/pricing/) 11.8 as an experimental feature. Smartcard authentication against an LDAP server may change or be removed completely in future releases.
GitLab implements a standard way of certificate matching following
[RFC4523](https://tools.ietf.org/html/rfc4523). It uses the