use_ssl set to False, cannot connect to ldap server with plaintext

[fansongfs]

Bug description

with configuration of :

c.JupyterHub.authenticator_class = 'ldapauthenticator.LDAPAuthenticator'
c.LDAPAuthenticator.lookup_dn = False
c.LDAPAuthenticator.use_ssl = False
c.LDAPAuthenticator.server_address = 'localhost'

I expect jupyterhub will authenticate user with ldap server through plaintext communication. but it will get
ldap3.core.exceptions.LDAPStartTLSError: startTLS failed - protocolError.

How to reproduce

1. set up sldap and jupyterhub in the same server
2. configure jupyterhub use LDAPAuthenticator with use_ssl = False

Expected behaviour

Authentication works

Actual behaviour

get exception ldap3.core.exceptions.LDAPStartTLSError: startTLS failed - protocolError.

Your personal set up

I check source code, it seems following line of code(line 307~309) causing issue:
auto_bind = (
ldap3.AUTO_BIND_NO_TLS if self.use_ssl else ldap3.AUTO_BIND_TLS_BEFORE_BIND
)
when I use ldap3.AUTO_BIND_NO_TLS if use_ssl is false, the binding works.

Does LDAPAuthenticator support plaintext communication?

• OS:
• Ubuntu 22.04
• Version(s):
  jupyterhub 4.0.2

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[wsuzume]

I encountered the same problem and was able to resolve it using the same method.
Thank you very much @fansongfs !

I'm using docker and the details are as follows.

Host: RHEL8
Docker: 26.1.3
Image: jupyterhub/jupyterhub:4.1.5
Python: 3.10.12

c.JupyterHub.authenticator_class = 'ldapauthenticator.LDAPAuthenticator'
c.LDAPAuthenticator.server_address = 'our-ldap-server.com'
c.LDAPAuthenticator.server_port = 389
c.LDAPAuthenticator.bind_dn_template = ['uid={username},ou=people,o=our-company,c=jp']
c.LDAPAuthenticator.lookup_dn = False
c.LDAPAuthenticator.use_ssl = False

The patch I applied is as follows.

307         auto_bind = (
308             ldap3.AUTO_BIND_NO_TLS if self.use_ssl is False else ldap3.AUTO_BIND_TLS_BEFORE_BIND
309         )

[wsuzume]

When I tried to create a pull request with this patch, it resulted in errors during tests from Python 3.7 to 3.11.

Applying the changes proposed in pull request #216 and specifying use_tls=False might be a more fundamental solution.

[wsuzume]

Applying #216, that is, cloning and installing from https://github.com/loic-vial/ldapauthenticator and specifying use_tls=False instead of use_ssl=False resolved this issue.

Therefore, I believe this issue will be resolved in the next scheduled release.