This is a text-only version of the following page on https://raymii.org: --- Title : Samba Shares with Active Directory Login on Ubuntu 12.04 Author : Remy van Elst Date : 27-06-2013 URL : https://raymii.org/s/tutorials/SAMBA_Share_with_Active_Directory_Login_on_Ubuntu_12.04.html Format : Markdown/HTML --- This tutorial shows you how to set up a SAMBA server which authenticates all users to an Active Directory, including group based permissions. It uses Samba, Winbind, Kerberos and nsswitch. This allows you to have a Linux machine serving files via SMB, where your authentication and autorization for the files and folders is done via Active Directory.

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We are actually doing two things, we bind a Linux machine to the Active Directory (but we disable shell access for the users), and we then configure Samba to accept these users to the shares we set up. ### Introduction The data used in this tutorial: * Active Directory Domain: example.org * Realm/workgroup: example * Active Directory Server IP: 10.0.23.1 (Also DNS and NTP) * Share 1: Marketing * Allowed AD group: marketing * Share 2: Research * Allowed AD groups: research, development * Share 3: Dropbox * Allowed AD groups: Everyone with a domain account, Domain Users. * Share 4: CEO * Allowed AD users: CEO. This setup is tested with the following software: * Ubuntu 12.04 * Samba 3.6.3 * Active Directory on Windows Server 2008 mixed with Windows Server 2012. * Active Directory on Windows Server 2003 mixed with Windows Server 2008. ### Overview A summary of the steps we are going to do: * Install Packages * Configure NTP & DNS * Configure Kerberos * Configure nsswitch * Configure Samba * Join the Domain * Configure Samba shares * Test the setup You need to have a privileged account to join the Active Directory Domain. ### Install Packages On a freshly installed Ubuntu Server 12.04 we need to install the following packages to get started: apt-get install ntp krb5-user samba smbfs smbclient winbind krb5, Kerberos will ask some questions about your domain and a privileged user. You can enter through this, we are going to put our own config files. ### Configure NTP & DNS Active Directory (Kerberos in general) is very picky about the system time, so configure NTP to sync the time against your Active Directory NTP server. Edit `/etc/ntp.conf`: server 10.0.23.1 Now also edit your `/etc/resolv.conf` (or `/etc/network/interfaces`) file and change the DNS to your Active Directory DNS servers: # /etc/resolv.conf nameserver 10.0.23.1 search example.org # /etc/network/interfaces iface eth0 inet static [...] dns-nameservers 10.0.23.1 dns-search example.org We do this because Active Directory uses DNS for a lot of things. You can also setup your standard DNS servers to use an Active Directory DNS server as first upstream. ### Configure Kerberos What is Kerberos? Kerberos is a computer network authentication protocol which works on the basis of "tickets" to allow nodes communicating over a non-secure network to prove their identity to one another in a secure manner. Its designers aimed it primarily at a clientserver model and it provides mutual authenticationboth the user and the server verify each other's identity. [A good article on how Kerberos is used in Active Directory can be found here: http://technet.microsoft.com/en-us/library/bb742516.aspx][2] We need to set up Kerberos so that we can bind our machine against Active Directory and let users access the Samba share via the AD. Edit the `/etc/krb5.conf` file, remove everything and place the following in it, changing the `EXAMPLE.ORG` domain to your own Active Directory Domain: [libdefaults] ticket_lifetime = 24h default_realm = EXAMPLE.ORG forwardable = true [realms] EXAMPLE.ORG = { kdc = 10.0.23.1 default_domain = EXAMPLE.ORG } [domain_realm] .example.org = EXAMPLE.ORG example.org = EXAMPLE.ORG [kdc] profile = /etc/krb5kdc/kdc.conf [appdefaults] pam = { debug = false ticket_lifetime = 36000 renew_lifetime = 36000 forwardable = true krb4_convert = false } [logging] kdc = FILE:/var/log/krb5kdc.log admin_server = FILE:/var/log/kadmin.log default = FILE:/var/log/krb5lib.log We are now going to test Kerberos by getting a ticket for the Active Directory Administrator User. Make sure you have the password ready: kinit Administrator Password for Administrator@EXAMPLE.ORG: Now we check if we got a valid ticket: klist Ticket cache: FILE:/tmp/krb5cc_0 Default principal: Administrator@EXAMPLE.ORG Valid starting Expires Service principal 27/06/2013 07:17 27/06/2013 17:17 krbtgt/EXAMPLE.ORG@EXAMPLE.ORG renew until 28/06/2013 07:17 If this is not correct, check your Kerberos and DNS and NTP (time) settings and try again. ### Configure nsswitch nsswitch is used to tell the system that the Active Directory users are also valid users. We are going to configure it to also accept winbind users, which is what Samba uses after it has bound to the domain. Edit the `/etc/nsswitch.conf` and change the `passwd`, `shadow` and `group` lines to look like this: passwd: compat winbind group: compat winbind shadow: compat winbind Note that this might not work for you. If you have issues with the users later on, change these lines to this: passwd: files winbind shadow: files winbind group: files winbind [The NetBSD man page explains more than the Ubuntu man page: http://www.daemon- systems.org/man/nsswitch.conf.5.html][3] ### Configure Samba (#1) Now we need to set up Samba to also support the domain. Edit `/etc/samba/smb.conf` and remove everything, then place the following in it: [global] # No .tld workgroup = EXAMPLE # Active Directory System security = ads # With .tld realm = EXAMPLE.ORG # Just a member server domain master = no local master = no preferred master = no # Disable printing error log messages when CUPS is not installed. printcap name = /etc/printcap load printers = no # Works both in samba 3.2 and 3.6. idmap backend = tdb idmap uid = 10000-99999 idmap gid = 10000-99999 # no .tld idmap config EXAMPLE:backend = rid idmap config EXAMPLE:range = 10000-9999 winbind enum users = yes winbind enum groups = yes # This way users log in with username instead of username@example.org winbind use default domain = yes # Inherit groups in groups winbind nested groups = yes winbind refresh tickets = yes winbind offline logon = true # Becomes /home/example/username template homedir = /home/%D/%U # No shell access template shell = /bin/false client use spnego = yes client ntlmv2 auth = yes encrypt passwords = yes restrict anonymous = 2 log file = /var/log/samba/samba.log log level = 2 Save the file and restart all the daemons: /etc/init.d/winbind restart /etc/init.d/nmbd restart /etc/init.d/smbd restart ### Join the domain Make sure you still have a valid Kerberos ticket. If not, do a new `kinit Administrator`. Then execute the following command: net ads join -U administrator Output is like this: Enter Administrator's password: Using short domain name -- EXAMPLE Joined 'HOSTNAME' to realm 'Example.org' DNS Update for hostname.example.org failed: ERROR_DNS_GSS_ERROR DNS update failed! The DNS error can be ignored, make sure you create an A record and a PTR record manually. Restart all the daemons again: /etc/init.d/winbind restart /etc/init.d/nmbd restart /etc/init.d/smbd restart Also update PAM: pam-auth-update Now see if you can list the domain users and groups: wbinfo -u # lists all the users in the domain wbinfo -g # lists all the groups in the domain And also check if winbind and nsswitch are correctly working: getent passwd # should return a list with all users on the local system and from the active directory getent group # should return a list with all groups and their members, both from the local system and the active directory If this does not work, go back to the nsswitch configuration section and change the `compat` to `files`. ### Configure Samba (#2): Shares This setup reflects an average business. Two departments with their own share, and one dump folder for everyone. And a folder for the CEO so that he feels special. Do note that it is a good idea to clean the Dropbox every night with a cronjob, but let your users know that that happens. We are going to create the shares. First create the folders on the system: mkdir -p /sharing/{marketing,research,ceo,dropbox} chmod -R 0770 /sharing/ chgrp -R "Domain Users" /sharing/ Add the shares to `/etc/samba/smb.conf`: [Marketing] comment = Marketing path = /sharing/marketing/ valid users = @EXAMPLE\marketing force group = marketing writable = yes read only = no force create mode = 0660 create mask = 0777 directory mask = 0777 force directory mode = 0770 access based share enum = yes hide unreadable = yes [Research] comment = Research path = /sharing/research valid users = @EXAMPLE\development, @EXAMPLE\research force group = "domain users" writable = yes read only = no force create mode = 0660 create mask = 0777 directory mask = 0777 force directory mode = 0770 access based share enum = yes hide unreadable = yes [Dropbox] comment = Daily Emptied Dropbox path = /sharing/dropbox valid users = "@EXAMPLE\Domain Users" force group = "domain users" writable = yes read only = no force create mode = 0660 create mask = 0777 directory mask = 0777 force directory mode = 0770 access based share enum = yes hide unreadable = yes [CEO] comment = CEO Only path = /sharing/ceo valid users = EXAMPLE\ceo force group = "domain users" writable = yes read only = no force create mode = 0660 create mask = 0777 directory mask = 0777 force directory mode = 0770 access based share enum = yes hide unreadable = yes As you can see, an active directory group is defined with an `@`, and a user without. Also, when there are spaces in the groupname, you escape that with quotes: `"@EXAMPLE\Domain Users"`. [You can find a lot of information on the smb.conf file in the man page: https://www.samba.org/samba/docs/man/manpages-3/smb.conf.5.html][4] [Why do we force the mode on files and folders? Because of problems with MS word, according to the Samba documentation: https://www.samba.org/samba/docs/man /Samba-HOWTO-Collection/AccessControls.html#id2615334][5] Afterwards restart samba: /etc/init.d/smbd restart ### Testing it Create a few accounts in the groups used (set expiry date to 1 day so you don't forget to remove them) and use those accounts to test the shares. Create files and folders as one user, try to edit and remove them as another user. Also try to access the shares with a non-privileged user. If you run into errors, check your log files in `/var/log/samba`. Make sure that the capitalization and spelling is correct in the `valid users` part of the samba config file, and also check the permissions on the folders themselves with `ls -la`. You can set `valid users = any` to make check if there are errors or not. The `testparm` command is also very helpful for the samba config file part. [1]: https://www.digitalocean.com/?refcode=7435ae6b8212 [2]: http://technet.microsoft.com/en-us/library/bb742516.aspx [3]: http://www.daemon-systems.org/man/nsswitch.conf.5.html [4]: https://www.samba.org/samba/docs/man/manpages-3/smb.conf.5.html [5]: https://www.samba.org/samba/docs/man/Samba-HOWTO-Collection/AccessControls.html#id2615334 --- License: All the text on this website is free as in freedom unless stated otherwise. 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