Rex Roof writes: > I have some linux machines that I have configured for student access. > We are authenticating against our OpenLDAP tree and limiting which > users have access via an LDAP groupOfNames. This is all working > perfectly. > > This is the problem I am having. Any user with access to the system > can run the /usr/bin/finger command and do a name search against our > entire LDAP tree. I would like to limit the info available via > finger to just the users that have access to any particular machine. > How can this be controlled? I don't quite get this. If they can run /usr/bin/finger, can't they also run /usr/bin/ldapsearch - or if that is missing, an ldapsearch they've installed somewhere else? With "access to the system" do you mean someone who can log in, or just physical access to a system which allows anyone to run finger without logging in? The server doesn't know it is finger which is doing the search, but you can use access controls to limit searches to certain hosts, or only authenticated users, or whatever. You don't need to provide anonymous read access if all you need is authentication, so maybe you can turn off such search altogether. Also you can use the unchecked and size limits to ensure people can't just search for *, they must at least provide a match which narrows down the search well. -- Hallvard

I have some linux machines that I have configured for student access. We are authenticating against our OpenLDAP tree and limiting which users have access via an LDAP groupOfNames. This is all working perfectly. This is the problem I am having. Any user with access to the system can run the /usr/bin/finger command and do a name search against our entire LDAP tree. I would like to limit the info available via finger to just the users that have access to any particular machine. How can this be controlled?

Brett @Google wrote: > On Sat, Sep 12, 2009 at 1:08 AM, Rex Roof <rex(a)wccnet.edu > <mailto:rex@wccnet.edu>> wrote: > > > I have some linux machines that I have configured for student > access. We are authenticating against our OpenLDAP tree and > limiting which users have access via an LDAP groupOfNames. This > is > all working perfectly. > > This is the problem I am having. Any user with access to the > system can run the /usr/bin/finger command and do a name search > against our entire LDAP tree. I would like to limit the info > available via finger to just the users that have access to any > particular machine. How can this be controlled? > > > This sounds more like a firewall / iptables issue to your finger > server > than anything else ? No, doesn't sound like that to me. Essentially he wants an ACL that grants access to nss-ldap searches based on the target entries belonging to a group associated with a particular peeraddr. But at the moment, I can't think of any mechanism to do this in the current ACL engine. -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/

Rex Roof wrote: > Yes, or a configuration for PAM that limits which users it provides > information for. PAM doesn't return user information at all. This is strictly for nss- ldap. You could also add a filter to nss-ldap's config file. Unfortunately the most straightforward filter (memberOf=<the group DN>) won't work with OpenLDAP's memberof overlay. If your group was actually a dynamic group, then you could use the same filter criteria that the dynamic group uses. > -Rex

See the dynlist overlay: http://www.openldap.org/doc/admin24/overlays.html On 15/09/2009, Rex Roof <rex(a)wccnet.edu&gt; wrote: > > On Sep 15, 2009, at 10:41 AM, Howard Chu wrote: > >> Rex Roof wrote: >>> Yes, or a configuration for PAM that limits which users it provides >>> information for. >> >> PAM doesn't return user information at all. This is strictly for >> nss- >> ldap. You >> could also add a filter to nss-ldap's config file. Unfortunately the >> most >> straightforward filter (memberOf=<the group DN>) won't work with >> OpenLDAP's >> memberof overlay. If your group was actually a dynamic group, then >> you could >> use the same filter criteria that the dynamic group uses. >> >>> -Rex > > > From what I can tell, nss_ldap and pam_ldap use the same config file > in centos, /etc/ldap.conf. So they both use the same proxy user? > > What do you mean by dynamic group? I'm open to changing to some > other > setup. > > -Rex > > -- Sent from my mobile device http://www.suretecsystems.com/services/openldap/ http://www.suretectelecom.com

On Friday, 11 September 2009 16:08:17 Rex Roof wrote: > I have some linux machines that I have configured for student access. > We are authenticating against our OpenLDAP tree and limiting which > users have access via an LDAP groupOfNames. At the PAM level. > This is all working > perfectly. > > This is the problem I am having. Any user with access to the system > can run the /usr/bin/finger command and do a name search against our > entire LDAP tree. I would like to limit the info available via > finger to just the users that have access to any particular machine. What about the standard user information available via 'getent passwd' ? > How can this be controlled? If you are referring to the same information as in 'getent passwd', your first problem is whether you need the OS to be able to resolve UIDs to usernames for the users who should not have access. After that, worry about (the same information via) finger ...

On 15/09/2009 14:31, Roof,Rex wrote: > On Sep 14, 2009, at 5:21 PM, Buchan Milne wrote: > >> On Friday, 11 September 2009 16:08:17 Rex Roof wrote: >>> I have some linux machines that I have configured for student >>> access. >>> We are authenticating against our OpenLDAP tree and limiting which >>> users have access via an LDAP groupOfNames. >> >> At the PAM level. >> >>> This is all working >>> perfectly. >>> >>> This is the problem I am having. Any user with access to the >>> system >>> can run the /usr/bin/finger command and do a name search against >>> our >>> entire LDAP tree. I would like to limit the info available via >>> finger to just the users that have access to any particular >>> machine. >> >> What about the standard user information available via 'getent >> passwd' ? >> >>> How can this be controlled? >> >> If you are referring to the same information as in 'getent passwd', >> your first >> problem is whether you need the OS to be able to resolve UIDs to >> usernames for >> the users who should not have access. After that, worry about (the >> same >> information via) finger ... >> > > Yes! 'getent passwd' returns all of the 100,000 entries in my LDAP > tree, I'd rather it returned the 30 or so users that have access to > the particular machine plus whatever is in /etc/passwd. > > Is it possible to do this? Perhaps via a PAM configuration? If I understand correctly, you're enforcing access to this machine by telling PAM to allow only a given group, presumably via an option in pam_ldap.conf like "pam_groupdn cn=yourgroupe,dc=etc". But, NSS (and therefore finger), is still seeing all users in the directory, and not only the ones from that group? One solution would be to configure your libnss-ldap to use a binddn to connect to the LDAP server, and set up ACLs so that that binddn only has access to users from that group.