Authenticating users on LDAP based on Group name

Ben Humpert ben at
Thu Mar 26 13:52:19 CET 2015

2015-03-26 3:20 GMT+01:00 Jose Torres-Berrocal <jetsystemservices at>:
> I have setup the group in groupmembership_attribute as a naive intent to
> accomplish my goal.  If that is not the correct parameter I will really
> appreciate your help on where I should set my Group and the syntax.

Well, the setting clearly asks for an attribute such as sAMAccountName
or userPassword. The name of a group is a value, the value of the
attribute cn. So yes, it is not the correct parameter ;)

> On my first email I included my LDAP.conf file as generated by pfsense.
> I think is closed as needed because I was successful matching user/pass
> with AD when group membership_attribute is default, but for all Users.  Now
> I need to change it to consider the Group.

Setting up user authentication is kind of simple. You just need to
match the basedn, filter and base_filter to your directory and that's
it. After understanding how these settings are merged into a search
request it is also easy to set up group authentication. I did so after
working with XLAT, now it's easy for me but before I had no clue at
all what I was doing :)
What helped me much was the information that unlike in databases like
*SQL you always want to get only ONE result in Directories, thus the
filter needs to be as strict as required to only find one user or
group. If you would find more how should Radius know which is the
correct entry?

The original ldap file says the following about membership_filter

"Filter to find group objects a user is a member of. That is, group
objects with attributes that identify members (the inverse of

and this about membership_attribute

"The attribute in user objects which contain the names or DNs of
groups a user is a member of. Unless a conversion between group name
and group DN is needed, there's no requirement for the group objects
referenced to actually exist."

That means that if your groups have attributes which contain the names
or uids of the users that are member of that group you do not use
membership_attribute but membership_filter. If instead your users have
attributes containing the names or gids of the groups the user is
member of then you use membership_attribute instead of

What is the case in your setup? Could you post an example of a group
and as well an user like the one below?

# Guest, Groups,
dn: cn=Guest,ou=Groups,dc=example,dc=com
objectClass: posixGroup
objectClass: top
objectClass: radiusProfile
cn: Guest
gidNumber: 17068
memberUid: guest
memberUid: tobtsc
memberUid: marhab

# guest, Users,
dn: uid=guest,ou=Users,dc=example,dc=com
objectClass: posixAccount
objectClass: top
objectClass: inetOrgPerson
objectClass: radiusProfile
gidNumber: 0
uid: guest
uidNumber: 18459
dialupAccess: Yes
cn: Guest

As you can see, the attribute "memberUid" is used to store the names
of those users who are member of the group Guest, thus
membership_attribute is not in use in my setup.

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