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LDAP Authentication in Linux
Posted by
ScuttleMonkey
on Sun Sep 03, 2006 02:34 PM
from the roadmaps dept.
from the roadmaps dept.
hausmasta writes "HowtoForge has published a walkthrough to show you how to store your users in LDAP and authenticate some of the services against it. It will not show how to install particular packages, as it is distribution/system dependent, instead it will focus on pure configuration of all components needed to have LDAP authentication/storage of users. The howto assumes that you are migrating from a regular passwd/shadow authentication, but it is also suitable for people who do it from scratch."
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Ldap on its own is not enough (Score:3, Interesting)
Using ldap itself is really not much better than using NIS, aside from the fact that it can contain much more than just the user database.
Re: (Score:3, Informative)
Active Directory, you mean recreate DCE (Distributed computing environment) using Kerberos for authentication and an x.500 derived directory for storing services and user groups and attributes?
Microsoft did nothing original with AD except to use LDAP instead of CDS (good move CDS sucks) and try to stuff service registration and discovery into DNS (yuck, LDAP would be much better for that). That said, DCE was way too complicated for most sites to set up, so it is good that MS brought it to the masses in
I always wondered... (Score:5, Interesting)
Its relatively eay to setup and quite stable. This in combination with PAM should be the once and for all way of authentication.
If you have a directory like this you can add virtually everything to it, be it intranet pages, mailserver authentication, hell even an inhouse Jabber client for employees. This should be unified and used much more often.
The management is a blast with the ability to choose whatever LDAP-Frontend you might wanna use and worstcase you can go back to browserbased or console. Its really flexible, elegant and in a Unix style a tool for the job.
Who can enlighten me why this is still rather a niche? are Unixadmins simply too used to the passwd/shadow style auth?
Oh yeah: In case you are going to set it up stay the hell away from BerkeleyDB 4.3.
It can have some nasty surprises.
Re: (Score:2, Interesting)
Sad, but often true.
NordicEdge AB
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I also had a though meeting after the migration where the CEOs asekd me what the benfit was.
I replied: "Cheaper maintenance". Luckily I started this domain for them so I could also add "enhanced security, privacy" to the mix.
Otherwise I would have gotten into trouble too.
You are probably right. I was just wondering if there are architectural/technical issues I wasnt aware of.
Re:I always wondered... (Score:5, Informative)
OpenDirectory by Apple is also an LDAPv3 implementation be it more pure than MS's implementation. You can combine both AD and OD on Mac to get a unified Windows-compatible login capabilities in the network that also get the benefits of using OD (force preferences and security settings on users/computers) without schema changes on either side.
RedHat also relies on LDAP for network-wide authentication in their products as does IBM and recently even Novell and lots of companies use it for different purposes in one or another way.
Parent
Re:I always wondered... (Score:4, Informative)
Novell's been using it longer than pretty much anyone. Check out NDS [wikipedia.org] for more info. Microsoft was more or less copying Novell, not any of the UNIX vendors (who were mostly still using NIS and friends when active directory came out).
Parent
Re: (Score:3, Interesting)
One of our former (and rather forward-looking) sysadmins moved our servers over to a centralized Kerberos+LDAP (via PAM) authentication and authorization system. He left for greener pastures; and since then I've seen a series of (mostly pretty young) sysadmins that just have this innate dislike for any sort of centralized management. It usually starts with complaints about OpenLDAP; but pretty soon you realize it's not the app, since they view any replacements wit
Re:I always wondered... (Score:5, Insightful)
Maybe you have a brain the size of this guy [wikipedia.org]. I don't know. I have tried a few times in the past to set up LDAP and all the documentation is written by space-aliens as far as I can tell. I can't even penetrate the language used, let alone follow the steps prescribed.
This Fine Article is no different. After about the 3rd sentence I have no idea what is being described, because we're already talking about "a replication" but this has not been defined. It's all like that: undefined terms and references, and exhortations to read the ldap man pages if you want to understand what is going on. The man pages are also full of undefined terms and references, except they are presented in highly-compact text blocks with bad grammar.
LDAP is niche because it is so freaking impossible to figure out. That's why.
Parent
Other options (Score:3, Informative)
For administration, check out JXplorer. It makes it easy to add/delete/modify users.
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LDAP for everything (Score:5, Interesting)
Windows Desktops (Samba PDC and BDC -> LDAP)
Linux pam_ldap + nss -> LDAP and NFS shares
You can log into either a windows desktop or linux box and have the same file shares open. Windows has H: and Linux is
Then for email, postfix + dovecot -> ldap. You can store not only use the same username password as for linux, but you can add unlimited number of real-time mail aliases to each user. Also supports virtual domains.
Directory services for phone numbers, room locations, etc. in ldap. Mapped to email clients search/contact lists.
squid + ldap and apache + ldap, secure login to website.
Squirrelmail/horde both use ldap as well. Auth is done via imap, but horde can do much more with ldap. Both can use it for directory services.
Admin can be done either via CLI smbldap-tools, php ldap admin, gq (ldap tree browser), or ldapmodify if you're hard core. Plus with sync'ing data to other sites they have a copy of the data for their BDC/etc. If I need to add/modify a user there is only one place that needs to be modified. And I can do it from home. =)
Our wiki Linux LDAP Howto (Score:3, Informative)
I hope you find it useful.
LDAP/Postgres? (Score:3, Insightful)
So where's the HOWTO for porting OpenLDAP to Postgres for its datastore? There's some HOWTOs for porting it to MySQL, but MySQL doesn't scale as well as Postgres, and existing Postgres installs are out of luck. The few existing LDAP/Postgres HOWTOs [google.com] seem inconclusive, untested. And some of the commercial products that advertise the feature don't even respond to emails to sales departments asking about the cutover.
As long as Slashdot is staring down "LDAP Auth in Linux", how about taking it to (and over) the Postgres wall?
Re: (Score:2)
SPLAT - Scalable Periodic LDAP Attribute Transmogr (Score:3, Informative)
Authentication with Apache Directory Server? (Score:2)
The article uses OpenLDAP as the LDAP server. Has anyone got this to work using the Apache Directory Server [apache.org]?
Host-based control (Score:2, Informative)
Installing the software never was the problem (Score:2)
Nested groups (Score:3, Interesting)
LDAP is NOT an authentication service (Score:4, Insightful)
First, LDAP is NOT an authentication service. I cringe a little whenever someone mentions using "LDAP authentication" for anything other than LDAP clients. Some of these tools use LDAP as a make-shift "pass-through" style authentication service. This is like passing credentials to an SSH server to authenticate web clients (only SSH would be more secure since it enforces confidentiality and integrity).
Second, if you are going to use LDAP like this, make sure the bind is being conducted over SSL. Using SASL would be even better but that's a little harder for a long lived service account and somewhat pointless if you already have Kerberos setup. With a plain bind you're sending passwords in clear text. Do not ever do that or someone will eventually come to your cube asking funny questions.
Finally, using LDAP as an authentication service does not provide Single Sign-On (SSO). You basically have to store some kind of token in the user's HTTP session which means someone could get your session ID and impersonate you (e.g. inadvertantly send a link with a session ID in it).
In general I don't recommend using LDAP as a make-shift authentication service as it is very easy for it to be insecure. Use Kerberos through and through people. It's the correct way to do things, it scales well and it's portable across both UNIX and Microsoft.
I pride myself ... (Score:4, Interesting)
My OpenLDAP stores:
POSIX User Attributes
Samba User Attributes
Radius User Attributes
eGroupware User Attributes (Egroupware accounts.)
DNS Information for our internal DNS Server
DHCP Lease information.
I use Kerberos with ssh-agent to distribute software RPMS for Mandriva Linux to mass distibute RPMs with a single command.
I have Samba Kerberos enabled so that Samba will not repeatedly ask for usernames and passwords, and requires zero configuration.
I have had the code to Egroupware modified so that eGroupware, and Nagios can use Apache's mod_auth_kerb addon to authenticate eGroupware users with a single click instead of a whole second login process.
I'm currently workong on creating a Samba Authenticated gateway with NTLM-SPNEGO support so that kerberos will handle Squid too.
All I need now is for someone to make the modifications nesessary to eGroupware's XMLRPC so that Kontact could use Kerberos and I would have the "Exchange Killer" I always wanted.
All of my users use Samba for network browsing under KDE's Konqueror, with Kerberos and LDAP, it just works.
I consider this my shining accomplishment.
I like to have myself believe that I accomplished "Active Direrctory" under Linux now. I don't use Windows at all in this network, so keep that in mind. The eGroupware people can attest to what a past I am. bugging them to include Kerberos detection in session management. But it all works.
Reliability (Score:3, Interesting)
But, what happens when the LDAP service isn't available?
I say service to not distinguish between a physical server, a cluster of servers, a crashed openLDAP process, broken network link, yadda, yadda, yadda.
With AD if a PDC isn't there, you can still login if you've logged on before.
The article really should have mentioned nss_updatedb and pam_ccreds from PADL [padl.com] (I don't know if there are any other alternatives, nor do I know if that actually work, sounds like they do though).
Re: (Score:3, Interesting)
Indeed...
Where I work one of my 'genius' predecessors set up a Linux fileserver with LDAP 'authentication' (nice euphemism that). LDAP is only used for samba fileshares... and for login.
The LDAP server runs on the fileserver itself, so at least it doesn't have to connect to a remote LDAP server.
He did a lovely piece of work, hacking it into place on a debian woody system, butchering the PAM config to make it appear to work.
He is long gone but his legac
Re: (Score:3, Informative)
I'd change it back, or if you're not using NIS, give just "passwd: files ldap" a shot, both files and compat are redundant at best. Whichever PAM file you have there is odd, auth should fail if a "required" module doesn't succeed. Here's mine:
LDAP is a pain in the arse (Score:3, Interesting)
Total pain in the ass to setup
Total pain in the ass to maintain
Now, I am using radius for the same thing. It works a lot better, because lets face it. PostgreSQL or MySQL is a hell of a lot easier to work with then LDAP.
LDAP does have its place. If you are looking to tie more then just auth into a profile, then LDAP is the choice. If you just want auth, use something Radius.
Of course, if you are a total LDAP guru, you are gonna recommend LDAP. But for average admins, or quick setups. LDAP isn't the way to go.
This rocks (Score:4, Interesting)
Why does it rock so much? LDAP seems unique that, unlike almost every other authentication method under the sun (NIS, NIS+ radius) it can be used on a number of devices. Additionally LDAP tends to be a great back-end for other authentication protocols (i.e. radius) can use an LDAP backend.
Practically speaking, often times all someone needs to do is have read access to a device to find out if an interface is up but many system admins give up if they don't have the ability to centralize and allow the company to become altogether too dependent on them. LDAP basically gets rid of this hassle and the administration is minimal. This means that the system admin gets paged less and more people can get work done with better efficiency.
Re: (Score:3, Interesting)
You can also have all your software that is LDAP aware authenticating against the same username/password (assuming they don't already support the stuff like PAM or the like).
If you really want to, you can also setup samba to use it and you can have XP machines join the domain, get the users in the domain all that fun stuff. (Was going to do this in a small lab I help at, ended up not because I realiz
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Huh? Surely Kerberos is more complex than plain LDAP authentication?
Re:Why would one want to do this? (Score:4, Informative)
And a HELL of a lot less secure. You would be better off doing nothing than doing plain LDAP authentication.
And for large insitutions, Kerberos gives you a credential that can be used multiple places. NFS, AFS, websites (with SPEGNO goodness), may services such as SSH, IMAP, etc.
Unless this is for a 192.168 network in your basement, there is NEVER a good reason to do LDAP authenticaion. That is not what it was designed for, and certainly not something it is good at.
Finkployd
Parent
Re: (Score:3, Informative)
Put together pam_ldap and pam_krb5 and you can do a lot of nifty stuff. You probably wouldn't care about hardly any of it for a standalone computer, but for a true multiuser system in a multisystem environment... almost
Re:Why would one want to do this? (Score:5, Informative)
With some decent admin tools you can even share your users between variants of Unix and Windows environments.
There are some advantages of LDAP over NIS which are worth mentioning. LDAP can be made more secure than NIS (NIS+ is better in this respect, but oh so much more of a pain to administer) through the use of SSL or better authentication methods. LDAP will usually scale better for many thousands of users than plain NIS. NIS is limited as to what data may be stored for a user, which is ok if all you want your user database for is authentication and basic authorization, but LDAP is much more flexible if you need to store other user information and would rather have a single user store.
There are some sites that even use Unix LDAP clients to authenticate to an Active Directory service running on windows platforms. This can be done much more transparantly with LDAP than many other authentication methods.
http://www.nordicedge.se/ [nordicedge.se]
NordicEdge AB
Parent
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Re: (Score:3, Informative)
You can also keep NIS around just for those maps.
Re:Why would one want to do this? (Score:4, Informative)
A quick google and here is a link you might like to look at:
http://www.linuxjournal.com/article/6266 [linuxjournal.com]
There are many other sources of information on this out there.
Anthony Whitehead
NordicEdge AB
Parent
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Re: (Score:3, Insightful)
It's amazing how many Slashdotters think that the only computers are those used by individuals. In serious organization, you have hundreds or thousands of people using your systems, and maintaining a separate password file for each one is just unthinkable. So you have a central authentication facility, such as Active Directory, NIS, or LDAP.
Re:Why would one want to do this? (Score:4, Interesting)
you are right on... when it comes to compliance and SOX requirements, getting all of your machines authenticating against one directory (AD or otherwise) makes perfect sense. I am sure there are a few sys admins here who have been asked for login failure and share access permissions across all of their network machines. adding more 'directories' makes it even more fun to gather these reports, comb through logs, look for changes across all the flavors of *nix and then the msft event logs, even network syslog...
There are a few companies out there who have built product lines that allow unix machines to authenticate against AD, their machine accounts can have Windows Group Polices and managed under one single console, they have the ability to appear in SMS as any other machine for reporting and hardware inventory and also to send their performance metrics over to MSFT MOM...
Why in the HELL would anyone want to authenticate against AD? well, it is simple really.. MSFT DID do the LDAP/Kerberos thing right and have been doing it right for a long time. They also have the whole pass-through, single id thing going and it works just fine in AD (when its an all windows network)... and its EVERYWHERE... how many LARGE companies are using whitepages/ldap type directories for authentication and how many are using AD? its a valid question to ask and what is happening is that most ARE already on AD or are moving to AD and they ARE using Exchange and this put AD into a space of being one of the main components of an enterprise. So why not just toss the unix machines in there as well?
yes, it empowers windows AD... but the first solution below (from quest) does not take anything out of the unix guys bag of tricks... in fact it allows for the unix guy to actually do things against AD that before was a pain to setup/admin...
anyway... sunday, should be out walking the dog and playing frisbee with the kids or working on my short game... check out http://www.quest.com/landing/?ID=531 [quest.com] or http://www.centrify.com/ [centrify.com] for some good info on two companies that are doing this for the *nix world now...
Parent
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Re: (Score:3, Insightful)
Try changing your root password on 10 different servers on a regular basis.
Then issue accounts for 55 people on a combination of those servers, depending on which kind of job they do.
Also, each of those servers run different services, which some people need to have access to.
This leads to the situation where it is very common for people to have 6 different passwords, and this is the situati
Re:Why would one want to do this? (Score:4, Insightful)
You aren't thinking of putting your root login under LDAP are you?
Not meaning to be rude, but please, don't be such an idiot.
What happens when the LDAP server falls over and you are at the console and you try to login as root... and it can't authenticate root because the LDAP subsystem is down? Reboot and pray that LDAP starts up ok?
Parent
Re: (Score:3, Interesting)
Unix login doesn't have separate "username" and "domain" prompts like WinNT does. So here's what you do: Make "root" always a local user, and if you need an centralized "administrator" user, you create another user and add it to the "wheel" group or to /etc/sudoers or whatever, and that user can run "su" or "sudo -s" to get a root shell when necessary.
Funny story: A few years ago, we were testing Active Directory on some Win2K boxes. One of the security policies you can set is "disable the local adminis
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Re:Password only (Score:4, Interesting)
Parent
Re:Password only (Score:4, Insightful)
Parent
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So...what's the difference between this and having only usernames?
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(Unless, of course, you speed up the backend by storing each end-user's passphrase in clear -- but that's very bad, as a successful attack on one of the authentication servers could immediately reveal the plaintext passphrase of every user.)
So we make users type in their username first
Re: (Score:2)
I followed this guide: Implementing a Disconnected Authentication and PDC/BDC Relationships Using Samba and OpenLDAP [linsec.ca].
The only problem with it is, and this is only on my laptop (it's supposed to work), is changing passwords has to be done on the master LDAP server. Has something to do with update referrals, maybe PAM_LDAP doesn't follow them, but right now it's not a big issue for me so I haven't really looked into it.
Other than that, it works great (when it works). Replication goes through immedately, and