Magic Triangle Setup with Windows File Server backed Portable Home Directories.

Recently I was hired to give my opinion about merging an existing Macintosh Open Directory(OD) network into a Windows Active Directory(AD) network. This was being done because Company A merged with Company B, and Company B being more powerful and larger wanted to stay with their AD infrastructure. My opinion was to move to a “Magic Triangle” setup where an OD server is bound to an AD Domain Controller(DC). The users and groups are managed by Active Directory, however the Mac clients are bound to both AD and OD for the purpose of being able to hand out MCX records to users, groups, and computers. I wrote this how to because no matter how much documentation I read I have not been able to find some of the key pieces of information I needed to accomplish this goal. On a side note, I would like to give a big hello to Alper Bac, current Systems Administrator of Cohos Evamy for his invaluable help in solving some of the AD configuration issues we were having.

On the Mac Server 10.6

Step 1: Check the Active Directory configuration.
Make sure your Active Directory server and its DNS service is properly configured and running.

Step 2: Turn on Open Directory service.
Use Server Admin to turn the Open Directory service on. After the service is turned on you can configure Open Directory service settings.

Step 3: Ensure the computer is a standalone directory service.

Step 4: Connect to Active Directory.

• Go to Server Admin, Open Directory.
• Click Settings button at top, then the General tab. The window should report that its role is “Standalone Directory.” If this is correct you can now click change, otherwise go to Step 3.
• In the pop-up dialogue choose “Connect to another Directory”
• Then Continue, and click “Open Directory Utility”
• The Directory Utility application will appear. If it is locked please unlock it.
• Ensure that active directory is uncheck
• Double click “Active Directory”
• Type in your domain and expand the arrow beside “Show Advanced Options”
• Ensure that “Create mobile account at login” and “Force Local home directory on startup disk” is uncheck. Then click OK
• Quit Directory Utility
• Back in the Open Directory Wizard box click Done
• Open System Preferences and go to Accounts
• Click on Login Options and Click “Join”
• Type the name of Active Directory Domain Controller (DC) in where it says “Server:” as well as the AD Admin user/password credentials in the appropriate boxes. Also give the computer an record name. This name will be the record that is created in Active Directory.
• Once joined the Mac will ask about Kerberos. Just ignore this for now.

Step 5: Set up an Open Directory master.

• Go to Server Admin, Open Directory
• Click Settings button at top, then the General tab. The window should report that its role is “Connected to another directory” If this is correct you can now click change, otherwise go to Step 4.
• Choose the first option “Remain connected and set up an Open Directory Master”
• If it complains about Kerberos just ignore this again.
• Setup the diradmin account. Give it a secure password as this is our Directory Administrator account.
• Now type in a relevant LDAP Search Base. If you don’t know what should go here just click continue. However if you don’t know what goes here yet you’re trying to integrate a Mac into AD I must say that you may be in over your head.
• Confirm your settings and click continue.
• Now in Server Admin we want to set a policy under Open Directory. So click on Policies tab and then Bindings subtab and enable the “Require authenticated binding….” check box.

Step 6: Disable Kerberos on Open Directory master.
Disable Kerberos on your Open Directory Master server to avoid conflicts with your Active Directory Kerberos realm. In a terminal type: (use the diradmin credentials)
sudo sso_util remove -k -a username -p password -r NAME. OF.KERBEROSREALM

Step 7: Kerberize services.
Kerberize your Open Directory server services with the Kerberos realm of your Active Directory server, in a terminal type:
sudo dsconfigad -enablesso

On the Windows Server 2003

What we need to do is assign a home folder to an existing user account. So let’s grab the user account “Test” and map a home folder to it.

• Go to Start, Administrative Tool, Active Directory Users and Computers
• Right click domain name and search for users
• Open Properties and then profile tab
• Click the “home folder” radio button and select an unused drive letter. For our example it will be “Z:” and then enter beside it the Windows File server fqdn in this format. \\fqdn\share\username
• Once you accept Windows will go and create this folder and assign all the appropriate ACLs

On the Mac Client 10.5

What we need to do on the Mac client is bind it to both AD and OD.

Active Directory

• Login as a the local admin user
• Open Applications/Utilities/Directory Utility.app
• Click on “Services” and then double click “Active Directory”
• Expand the Show Advanced Options arrow and disable “Force local home directory on startup disk”
• Now click on “Directory Servers” and click on “+”
• From the drop down select “Active Directory” and type the name of the DC
• Enter the computer ID and AD username/password and click join.
• If this fails then try clicking on Services and double click on Active Directory
• Type in the domain and client ID here and click “Bind”

Open Directory

• Open Applications/Utilities/Directory Utility.app
• Click “+” and select “Open Directory” from the drop down menu
• Type in the name of the ODM
• The computer should ask you for the OD diradmin password and client ID. Type in the same ID as you did for the Windows box (for consistency’s sake)

Now you should have two directory servers listed in the Directory Utility both with green lights.

You should now have a working Magic Triangle. The user and group accounts come from Active Directory and their home folders come from a Windows back File Server. We can now use WGM to introduce things like Portable Home Directories and MCX records. Yay!

Portable Home Directories

• Open WGM (WorkGroup Manager) and authenticate as diradmin
• Create a new group called “Mobility” we’re going to use this group to designate PHD users.
• Under the members tab click on the Plus sign, a side bar should appear.
• At the top of the side bar will be a text string like “Directory: /LDAPv3/127.0.0.1” click on this and change it to “/Active Directory/All Domains”
• Wait up to a couple minutes and you will start to see users from Active Directory appears. You can drag these users into the members pane of WGM. AFAIK you can also embed AD groups although I’ve never tried this.
• Now we have an OD group with an AD user member as well as a computer record from the mac client.
• Let’s click on Preferences for the mobility group and then click on “Mobility” under Overview tab.
• Under account creation tab click on “Always” and check “Create mobile account when user logs into network account” a
• Then click on rules tab and select always for all three subtabs yet leave their default values. Except for checking on “Show status in menu bar” under “options” sub tab
• Now try logging in with your AD account again and watch as the mac creates you a PHD and enables the HomeSync menu.

If you have problems with this process then feel free to leave a comment with some contact info and I’ll try to get back to you and help. I’ll have another post coming up for you Windows Sysadmins on how to easily managed your mac clients with Group Policy.

Snow Leopard Server and Linux client using LDAP and libpam-krb5

This is an extension article to my previous article Open Directory, Kerberos, Single Sign On (SSO) and CentOS with SSH and Kerberized NFS Home Directories. I had some requests from different Linux users out there how to incorporate authentication for Linux flavours other than CentOS. For this example we’re going to use Debian Lenny with some Ubuntu 10.04 refs thrown in.

Preperation – LDAP

First download all the packages that we’ll need.
Debian
apt-get install nss_updatedb ldap-utils libpam-ldap libnss-ldap nscd
Ubuntu
apt-get install nss_updatedb ldap-utils libpam-ldap libnss-ldap nscd nslcd
During the installation debconf should ask you some questions, here are my answers

LDAP server Uniform Resource Identifier: ldap:/// (Note the "ldap://", NOT "ldapi://"!)
Distinguished name of the search base: dc=foo,dc=bar
LDAP version to use: 3
Does the LDAP database require login? No
Special LDAP privileges for root? No
Make the configuration file readable/writeable by its owner only? No
Make local root Database admin. No
Does the LDAP database require login? No
Local crypt to use when changing passwords. crypt


If you’re not on Debian you can edit these options in the file /etc/ldap/ldap.conf and /etc/libnss-ldap.conf

Next, edit /etc/nsswitch.conf and change

passwd: compat
groups: compat

passwd: files ldap
groups: files ldap


Now restart the nscd service ( and nslcd if you’re using Ubuntu 10.04 )

Verify you can see the users via LDAP with the id or getent commands

jordan@elm:/$ id jordan
uid=1000(jordan) gid=100(users) groups=1001(ldap-admin),1022(fgstaff),1023(ssh-access),100(users)


jordan@elm:/$ getent passwd | grep jordan
jordan:x:1000:100:Jordan Eunson:/net/home/jordan:/bin/bash
jordan@elm:/$


Preperation – libpam-krb5

Download and install the packages
apt-get install krb5-config libpam-krb5

Then edit your /etc/krb5.conf file. Now here what you *could* do is copy the one from you Mac. If you have a Mac client already bound to your Open Directory installation then open the file /Library/Preferences/edu.mit.Kerberos and copy and paste the content to /etc/krb5.conf

Here is an example of mine for the realm FOO.BAR

[libdefaults]
default_realm = FOO.BAR
[realms]
FOO.BAR = {
admin_server = od-master.foo.bar
kdc = od-master.foo.bar
}
[domain_realm]
.foo.bar = FOO.BAR
foo.bar = FOO.BAR
[logging]
admin_server = FILE:/var/log/krb5kdc/kadmin.log
kdc = FILE:/var/log/krb5kdc/kdc.log


To test to see if this is working type the command kinit and see if we can get a ticket from the Kerberos Key Distribution Center


bart:~ jordan$ kinit jeunson
Please enter the password for jeunson@FOO.BAR:
bart:~ jordan$ klist
Kerberos 5 ticket cache: 'API:Initial default ccache'
Default principal: jeunson@FOO.BAR

bart:~ jordan$


Kerberos Authentication

Now that we have our Kerberos client working we can integrate the local system to LDAP for user lookup and Kerberos for passwords with PAM libraries.

/etc/pam.d/common-account

account sufficient pam_unix.so
account required pam_krb5.so


/etc/pam.d/common-auth

auth sufficient pam_unix.so nullok_secure
auth sufficient pam_krb5.so use_first_pass
auth required pam_deny.so


/etc/pam.d/common-session

session required pam_unix.so
#session required pam_mkhomedir.so skel=/etc/skel/ umask=0022
session optional pam_krb5.so minimum_uid=1000


Now try to login to your Linux client either on the console to see if it works. To finish up with Kerberizing the client please read this article

Open Directory, Kerberos, Single Sign On (SSO) and CentOS with SSH and Kerberized NFS Home Directories

This article is a pseudo continuation of the article: Using Network Accounts on a Linux Client with Open Directory Leopard Server. In this article I’m going to be going over at a high level the single sign-on environment in Mac OS X Server and at a low level on integrating Kerberized SSH and NFS and CentOS.

Please note the benefits of Kerberized NFS is that if a local computer is compromised the attacker will not be able to read NFS shares because they will not have a valid Kerberos ticket. Oh… and the whole NFS stream will be encrypted. (pow!)

Open Directory and Kerberos

Taken from Apple’s site: Picture walking into the local county fair, and you are given two choices. You can either use your credit card at the entry of every ride or you can use it once at a booth, which grants you a ticket that you can use for the remainder of the day. It’s a pretty simple choice if you’re concerned about the security of your credit card information and want to have a hassle-free day at the park.

This is exactly what Kerberos accomplishes in its implementation of Single Sign On in network environments. At the beginning of the workday, a user enters his/her password into the system once; this action decrypts a ticket from a server running as a Kerberos Key Distribution Center (KDC). The ticket holds a set of encrypted keys, which are used throughout the day to authenticate user access without exchanging sensitive password information. It expires after a given amount of time (typically one day), so even if a would-be intruder sniffs it out and decrypts the information, the user-access information remains safe in the long term.

With your Kerberos ticket you can be granted password-less access to services across a multitude of platforms. You could be on your Mac client with a valid Kerberos ticket and authenticate to a Linux VNC server, or a Mac AFP/NFS server, or a simple SSH session. The possibilities are mind blowing!

As a side note: in this article the OD master will be referred to as foo and the linux client named lame with the domain of example.bar

Open Directory and Kerberos Setup

This article assumes your are somewhat of a valid Systems Admin and were able of getting your OD environment up and running without issue. If not please read: http://www.makemacwork.com/master-open-directory-1.htm

At a real high level here are the steps:

1. set the hostname of your OD master
2. in Server Admin turn DNS on and setup
3. use `dig` to verify your forward and reverse DNS records to your OD master
4. set Open Directory in Server Admin to `Open Directory Master`
5. start binding clients

Extra tip and trick. In Server Admin -> Open Directory, there is an option I believe under Policy->binding that says something to effect of: Require authenticated binding between Directory and Clients. Enable this, then bind your Mac clients. What it will do when binding is ask for a username and password and computer record, enter your diradmin credentials and the FQDN of the host you are binding. For example, if your domain is example.bar and your client’s hostname is foo then enter: foo.example.bar

Kerberized SSH

For the Mac use /Applications/Utilities/Directory Utility to bind your Mac to the OD master.

On the Linux / CentOS side we’re going to setup Kerberos. First install kerberos with yum
sudo yum install krb5-auth-dialog krb5-devel krb5-libs pam_krb5-2.2.14-10 krb5-workstation


Now from the Gnome GUI go to System->Administration->Authentication

• Check, Enable LDAP Support
• Enter your LDAP search base and server address. Mine for this example would look like:



• If you don’t know your LDAP search base you can get it from the Overview Pane in Server Admin / Open Directory
• Click OK on this dialog box and then select the Authentication tab
• Check Enable Kerberos Support and click Configure Kerberos
• The realm should be the same as your LDAP search base in a different format, mine looks like this:



After binding your Mac and Linux clients let’s check to make sure it works. On either client type on the terminal kinit type in your password and then check to make sure you got your Kerberos ticket with klist. You should get the following response.

bart:~ jordan$ kinit jeunson
Please enter the password for jeunson@EXAMPLE.BAR:
bart:~ jordan$
bart:~ jordan$
bart:~ jordan$
bart:~ jordan$ klist
Kerberos 5 ticket cache: 'API:Initial default ccache'
Default principal: jeunson@EXAMPLE.BAR

Valid Starting Expires Service Principal
05/16/10 13:30:30 05/16/10 23:29:36 krbtgt/EXAMPLE.BAR@EXAMPLE.BAR
renew until 05/23/10 13:30:30


The command kinit is what is used to authenticate ourselves to the Kerberos Key Distribution Center (KDC) and grant us access to all Kerberized services. It is essential to have this ticket before proceeding.

Now that we know that Kerberos is working correctly we’re now going to setup Kerberized SSH. For your Mac and Linux clients we’re going to edit /etc/ssh_config or /etc/ssh/ssh_config depending on your Linux distro, you will want the following options set.

GSSAPIAuthentication yes
GSSAPIDelegateCredentials yes
GSSAPIKeyExchange yes
GSSAPITrustDNS yes


For the SSH server on the Mac side set the following options: /etc/sshd_config

GSSAPIAuthentication yes
GSSAPICleanupCredentials yes
GSSAPIStrictAcceptorCheck no
GSSAPIKeyExchange yes

KerberosAuthentication yes
KerberosOrLocalPasswd no
KerberosTicketCleanup yes


For the SSH servers on the Linux side set the following options: /etc/ssh/sshd_config

GSSAPIAuthentication yes
GSSAPICleanupCredentials no

KerberosAuthentication no
KerberosOrLocalPasswd no
KerberosTicketCleanup yes


Restart all SSHd services and make sure you have a fresh ticket from Kerberos.

Testing

First make sure you have a fresh new ticket using kinit and klist. Then try to ssh from your mac client to the Linux server or Mac server. It should let you in automagically. If not run ssh in ultra verbose mode to try and debug the problem. It’s usually comes down to some sort of DNS problem so make sure the Linux server you’re connecting to has DNS records for it and they resolve properly both forwards and reverse.

Kerberized NFS

First, you need to setup an NFS server on your Mac server. I’m not explaining how to do that. But I will say that you NFS mounts should be set to “Any” authentication setting for testing purposes. To learn more read the Apple server manual.

DANGER!
First ensure that the client machine has a DNS record and is resolvable both forwards and reverse and ensure that the /etc/hosts file isn’t treading on the DNS records. Also before we proceed I must make it clear that you are very careful with this section. You will be connecting to the Kerberos Key Distribution Centre that is served inside of your Open Directory server. If you accidentally break something there is a risk that you will break your installation of OD and you will have to rebuild the whole Directory.

SSH in the linux host and check out a kerberos for the directory administrator.

[root@lame]# kdestroy
[root@lame]# kinit diradmin
Password for diradmin@EXAMPLE.BAR:
[root@lame]# klist
Ticket cache: FILE:/tmp/krb5cc_3001_7WM4As
Default principal: diradmin@EXAMPLE.BAR

Valid starting Expires Service principal
05/16/10 23:28:42 05/17/10 09:28:42 krbtgt/EXAMPLE.BAR@EXAMPLE.BAR
renew until 05/17/10 23:27:45

[root@lame]#


With this ticket you can now login to the KDC server. The following command references the file /etc/krb5.conf to locate the KDC server, it is then passed the -p switch with the name of principle to use when connecting.

/usr/kerberos/sbin/kadmin -p diradmin@EXAMPLE.BAR

From here on in, you must be very very careful. This is the Kerberos Key Distribution Centre. We’re going to be adding three principles to the KDC; host, root and nfs. The last one, nfs, requires a special option to make it works. Please make sure to type the FQDN of the linux client.

addprinc -randkey host/lame.example.bar@EXAMPLE.BAR
addprinc -randkey root/lame.example.bar@EXAMPLE.BAR
addprinc -randkey -e des-cbc-crc:normal nfs/lame.example.bar@EXAMPLE.BAR
Now lets copy those principals out of the KDC to the local file system
ktadd -k /etc/krb5.keytab host/lame.example.bar@EXAMPLE.BAR
ktadd -k /etc/krb5.keytab root/lame.example.bar@EXAMPLE.BAR
ktadd -k /etc/krb5.keytab -e des-cbc-crc:normal nfs/lame.example.bar@EXAMPLE.BAR
quit


Make sure this worked by reading the /etc/krb5.keytab file:


[root@lame]# sudo klist -k /etc/krb5.keytab
Password:
Keytab name: FILE:/etc/krb5.keytab
KVNO Principal
---- --------------------------------------------------------------------------
4 host/lame.example.com@EXAMPLE.BAR
4 host/lame.example.com@EXAMPLE.BAR
4 host/lame.example.com@EXAMPLE.BAR
4 root/lame.example.com@EXAMPLE.BAR
4 root/lame.example.com@EXAMPLE.BAR
4 root/lame.example.com@EXAMPLE.BAR
4 nfs/lame.example.com@EXAMPLE.BAR
[root@lame]#


Now there are two daemons that need to be running to make kerberized nfs work. They are rpcgssd and rpcsvcgssd. To get this up we must edit the /etc/sysconfig/nfs file and uncomment the following lines:

MOUNTD_NFS_V3="yes"
SECURE_NFS="yes"

Then start up /etc/init.d/{rpcgssd,rpcsvcgssd} restart
Make sure to add them to the default run level

[root@lame]# /sbin/chkconfig rpcgssd on
[root@lame]# /sbin/chkconfig rpcsvcgssd on


Testing

Let’s try mounting a Kerberized NFS mount. First let’s make the folder /mnt/nfs Now issue a mount command.


sudo mount -t nfs -o sec=krb5p foo.example.bar:/Volumes/Data/Users /mnt/nfs
This "should" mount the NFS share on /mnt/nfs. Use the mount command again to see the krb5p option in action!
Some lines omitted
foo.example.bar:/Volumes/Data/Users on /Volumes/Data/Users type nfs (rw,nosuid,nodev,hard,intr,sec=krb5p,addr=10.10.10.10)


Tada! It Works!



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Using Network Accounts on a Linux Client with Open Directory Leopard Server

I have two linux machines at home and I want to be able to use my network home directory and network account from my Leopard Open Directory server. One is running Ubuntu 9.10 and the other OpenSuSE 11.2. Here’s what I had to do:

In this post I assume you already have an Open Directory environment and network based user accounts as well as AFP homes setup. In other words, a working Open Directory setup with bound AND working Mac clients.

Exporting User Home Directories with NFS

First we want to make sure that the home directories are being exported via NFS. Open Server Admin and connect to your OD master. At the top of Server Admin click on File Sharing and then your AFP home folder volume. Click on File Sharing up at the top and select your AFP home volume. The click on the “Share Point” button in the bottom pane and then “Protocol Options” (Note: if “Enable Automount” is not checked you either have the wrong volume selected or your configuration is incorrect)

In the Protocol Options drop down select the NFS tab and select a means by which to export the NFS share. I would recommend using subnet and if you know what you’re doing select a minimum security of “Kerberos v5 with data integrity and privacy” however you should only select this if you REALLY know what you’re doing. I will make a walk through for this at a later date. If you don’t know Kerberos like the back of your hand then I would select “Any” for now. Check Allow Subdirectory Mounting. Click OK and you’re done.

Ubuntu 9.10 Authentication

On the Ubuntu Linux client first install the necessary packages:

sudo apt-get install libpam-ldap libnss-ldap nss-updatedb libnss-db nfs-common nscd

In the following wizard just accept the default answers, they should be correct. Then edit /etc/ldap.conf and make it sure it contains the following lines. Note this is not a verbatim output of /etc/ldap.conf


host 192.168.1.1 # this should be the IP of your OD server or better yet service based CNAME record
base dc=example,dc=com # this is of course the ldap search base configured in the OD server
bind_policy soft


Now edit /etc/ldap/ldap.conf

BASE dc=example,dc=com
URI ldap://example.com

protocols: db files
services: db files
ethers: db files
rpc: db files


openSuSE 11.2 Authentication

On the command line start yast

Navigate to Network Services and then LDAP client type in your LDAP server IP and search domain, unclick TLS and bam you’re done. God I love Novell

Ubuntu 9.10 & openSuSE 11.2 Automount

Create the directory /Network/Servers then all that is needed is to create the following line in /etc/auto.master

/Network/Servers /etc/auto.net

Restart autofs

sudo /etc/init.d/autofs restart

After this you should be able to log in and access your home folder.

How-To Migrate DNS Server from 10.5 to 10.6

Test extensively

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Fixing Broken dyld Cache

If you get an error similar to

10/28/09 10:52:04 AM com.apple.fontd[423] dyld: shared cached file was build against a different libSystem.dylib, ignoring cache


Then you need to execute the following command

sudo update_dyld_shared_cache


Automating Snow Leopard Installation

I administer a small network of about 30 mac clients and was not looking forward to upgrading them all to Snow Leopard. Booting each one off of a DVD, running through the wizard that takes forever and then the first boot song and dance that I am sure will be playing in the waiting room for Hell. Then the idea hit me to use Netboot and Apple’s System Image Utility to automate the whole process!

System Image Utility

Apple’s System Image Utility (SIU) comes with the default install of Mac OS X Server. Its purpose is to create images that can be used in the NetBoot server. There are three types of images you can create, NetBoot; allows macs to boot over the network from a server-based disk image. NetInstall; installs Mac OS X over the network from a hosted disk image. NetRestore; restores a volume over the network from an Apple Software Restore disk image.

We’re going to focus on NetInstall, but more specifically the customization of these images. First insert your DVD of Snow Leopard. Then, open the SIU app and click NetInstall and then click Customize. The SUI window will then turn into an Automator workflow and the Automator Library window should appears beside it. You’ll notice in the Library window there are a bunch of “actions” here. What I want to do is have a workflow that will format the hard drive, change the default packages to install and then setup a user after the install.

Drag in the Customize Package Selection action and place it in between the two pre-existing actions in your work flow, this being Define Image Source and Create Image. Then expand the arrow beside Mac OS X and select the packages you want to install via the “Default” checkbox. Then drag in the Enable Automated Installation action into our workflow and place it between the package selection action and then create image action. You can choose here whether to let the user select the disk to install to or if it should auto install to the disk named: (whatever). Finally add the Add User Account action just before the create image action and enter your user’s account credentials. If you need to you can also add the “Add Package/Post Install Scripts” to install any custom software or post-install scripts that you need. For myself I used this feature to install Radmind tools. Before click “Run” make sure your workflow looks something like…

Netboot

Once the SUI has completed creating our image then launch Server Admin and enable Netboot and DHCP services. Configure DHCP to hand out address for your network. If you don’t know how to configure DHCP please read up at Apple’s website. Start DHCP and then click NetBoot. From here select Settings and then General. Check off the network adapter(s) that you want to use for serving out NetBoot. The select the Images tab and choose the image we just created as the default, also click the check box labelled Enable. Verify the protocol is set to NFS and click save then start. Note: don’t worry if you don’t have NFS enabled or configure, NetBoot will take care of all of that for you.

Now go to your client that you want to install Mac OS X on, turn it while holding down the “N” key. From here you can sit back and relax. Automator Power!