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Reply to topic   Topic: Apache 2.4: LDAP authentication very slow

Joined: 03 Feb 2020
Posts: 1
Location: USA, Tallahassee, FL

PostPosted: Mon 03 Feb '20 15:13    Post subject: Apache 2.4: LDAP authentication very slow Reply with quote

Apache 2.4.6
RHEL 7.7

This is a pretty new (about a week old) problem. My department Intranet uses authentication against the university's Active Directory environment, and authentication for end-users takes over 30 seconds. Subsequent page loads are nearly-instant, and after 15-30 minutes, the problem is back.

<Directory /var/www/html/intranet>
  AuthType Basic
  AuthName "Restricted files"
  AuthBasicProvider ldap
  AuthLDAPBindDN CN=dept-binder,OU=Generic-Logon,OU=Generic,DC=example,DC=edu
  AuthLDAPBindPassword lamepassword
  AuthLDAPURL ldaps://ldap-ad.example.edu:636/dc=example,dc=edu?sAMAccountName?sub

    require ldap-group CN=ug-dept-intranet,OU=Deoartment,OU=Dept-Groups,DC=example,DC=edu

Here are some relevant lines from error_log, showing an authentication take 37 seconds:

AH02034: Initial (No.1) HTTPS request received for child 36 (server dept.example.edu:443)
AH01626: authorization result of Require ldap-group CN=ug-psy-employees,OU=Dynamic,OU=Psychology,OU=FSU-Dept-Groups,DC=fsu,DC=edu: denied (no authenticated user yet)
AH01626: authorization result of Require ldap-group CN=ug-dept-intranet,OU=Dept,OU=Dept-Groups,DC=example,DC=edu: denied (no authenticated user yet)
AH01691: auth_ldap authenticate: using URL ldaps://ldap-ad.example.edu:636/dc=example,dc=edu?sAMAccountName?sub
AH02001: Connection closed to child 11 with standard shutdown (server dept.example.edu:443)

# 37 seconds pass

AH01697: auth_ldap authenticate: accepting jsmith
AH01713: auth_ldap authorize: require group: testing for group membership in "CN=ug-dept-intranet,OU=Department,OU=Dept-Groups,DC=example,DC=edu"
AH01714: auth_ldap authorize: require group: testing for member: CN=jsmith,OU=PEOPLE,DC=example,DC=edu (CN=ug-dept-intranet,OU=Department,OU=Dept-Groups,DC=example,DC=edu)
AH01715: auth_ldap authorize: require group: authorization successful (attribute member) [Comparison true (adding to cache)][6 - Compare True]
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Joined: 27 Jun 2016
Posts: 123
Location: Schömberg, Baden-Württemberg, Germany

PostPosted: Sat 08 Feb '20 8:00    Post subject: Reply with quote

sound like a timeout of ~30 seconds which is cached for 15-30 minutes. Would be interesting what is going on on the wire within these 30 seconds (tcpdump/Wireshark).

Within my text-LDAP-config I have additional three lines where the last one was commented as "to be used with apache2.4", but I can't remember why I have added this comment:
AuthLDAPRemoteUserIsDN On
AuthLDAPBindAuthoritative On
LDAPReferrals Off

Maybe you can check if these config-lines help or what happens between your webserver and the LDAP-server (looks like an Windows-AD-server)?

Best regards
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Joined: 07 Mar 2021
Posts: 1
Location: Warsaw, Poland

PostPosted: Sun 07 Mar '21 23:27    Post subject: Reply with quote

I've had exactly the same problem on Fedora 33 with Apache 2.4 and I've solved it by adding

LDAPConnectionTimeout 1

to the Apache global configuration:

I'm using LDAPS with TLS and I suspect that delay was caused by Apache trying to verify Active Directory/DC non-qualified (self enrolled) certificate.
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