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Naftuli Kay
Asked: 2015-12-05 14:43:02 +0800 CST

Unable to login via PAM and ldap: failed to get password

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I'm trying to have OpenVPN authenticate users via PAM over LDAP to an Active Directory server.

Here are the relevant parts of my configuration files:

/etc/openvpn/server.conf: 

# ...
plugin /usr/lib64/openvpn/plugins/openvpn-plugin-auth-pam.so ldap-login

/etc/nslcd.conf:

uri ldap://prod-adc1.mydomain.local
base DC=MyDomain,DC=Local
uid nslcd
gid ldap

/etc/pam.d/ldap-login:

auth      sufficient  pam_ldap.so minimum_uid=1000 use_first_pass
auth      required    pam_deny.so
password  sufficient  pam_ldap.so minimum_uid=1000 use_first_pass
password  required    pam_deny.so

When I try authenticating, I see the following in the logs:

/var/log/secure:

Dec  4 22:22:42 localhost openvpn[25505]: pam_ldap(ldap-login:auth): failed to get password: Authentication failure

/var/log/messages:

Dec  4 22:38:28 localhost openvpn[25504]: 1.2.3.4:37503 TLS: Initial packet from [AF_INET]1.2.3.4:37503, sid=c2d806cc 5c7c7ace
Dec  4 22:38:28 localhost openvpn[25504]: 1.2.3.4:37503 PLUGIN_CALL: POST /usr/lib64/openvpn/plugins/openvpn-plugin-auth-pam.so/PLUGIN_AUTH_USER_PASS_VERIFY status=1
Dec  4 22:38:28 localhost openvpn[25504]: 1.2.3.4:37503 PLUGIN_CALL: plugin function PLUGIN_AUTH_USER_PASS_VERIFY failed with status 1: /usr/lib64/openvpn/plugins/openvpn-plugin-auth-pam.so
Dec  4 22:38:28 localhost openvpn[25504]: 1.2.3.4:37503 TLS Auth Error: Auth Username/Password verification failed for peer
Dec  4 22:38:28 localhost openvpn[25504]: 1.2.3.4:37503 Control Channel: TLSv1.2, cipher TLSv1/SSLv3 DHE-RSA-AES256-GCM-SHA384
Dec  4 22:38:28 localhost openvpn[25504]: 1.2.3.4:37503 Peer Connection Initiated with [AF_INET]1.2.3.4:37503
Dec  4 22:38:31 localhost openvpn[25504]: 1.2.3.4:37503 PUSH: Received control message: 'PUSH_REQUEST'
Dec  4 22:38:31 localhost openvpn[25504]: 1.2.3.4:37503 Delayed exit in 5 seconds
Dec  4 22:38:31 localhost openvpn[25504]: 1.2.3.4:37503 SENT CONTROL [UNDEF]: 'AUTH_FAILED' (status=1)
Dec  4 22:38:36 localhost openvpn[25504]: 1.2.3.4:37503 SIGTERM[soft,delayed-exit] received, client-instance exiting

Have I configured PAM wrong? Is there something I'm missing in my login configuration?

EDIT: I'm able to login if I do the following:

ldapsearch -h prod-adc1.mydomain.local -b "DC=MyDomain,DC=Local" -x -D "[email protected]" -W

How do I map this over to the PAM LDAP module to get OpenVPN logins working as expected?

active-directory

2 Answers

  1. It looks like you need to configure /etc/nslcd.conf with your binddn and bindpw.

    See http://arthurdejong.org/nss-pam-ldapd/nslcd.conf.5

    Hope this helps!

    -Byron

    • 1

  2. Example of working setup (authorize users only against LDAP server, in the example I was using OpenLDAP, but AD is supported also in this module - openvpn-auth-ldap.so):

    openvpn-sever.conf:

    # Authorization against LDAP
plugin /usr/lib64/openvpn-auth-ldap.so /some/path/auth-ldap.conf

    auth-ldap.conf:

    <LDAP>
  # LDAP server URL
  URL ldap://server.intranet.eko-inwest.com.pl:389

  # Bind DN (If your LDAP server doesn’t support anonymous binds)
  # BindDN uid=administrator,ou=users,dc=x,dc=y
  # BindDN uid=admin,ou=Users,dc=x,dc=y
  # BindDN [email protected]

  # Network timeout (in seconds)
  Timeout 15

  # Enable Start TLS
  TLSEnable       no

  # TLS CA Certificate File
  # TLSCACertFile   /etc/ssl/ca.x.y.crt
</LDAP>

<Authorization>
  # Base DN
  BaseDN "ou=users,dc=x,dc=y"

  # User Search Filter
  #SearchFilter "(uid=%u)"
  #SearchFilter "(&(uid=%u)(objectclass=posixAccount))"
  # For Samba's schema
  SearchFilter "(&(uid=%u)(!(sambaAcctFlags=[DUL        ])))"

  # Require Group Membership
  RequireGroup true

  # Add non-group members to a PF table (disabled)
  # PFTable vpn-users
        <Group>
                # Match full user DN if true, uid only if false
                RFC2307bis      false
                BaseDN          "ou=groups,dc=x,dc=y"

                SearchFilter    "(cn=vpn-users)"
                MemberAttribute memberUid
        </Group>
</Authorization>
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