Friday, October 9, 2015

Adding linux host into Microsoft ActiveDirectory domain

This is a step by step instruction how to add GNU Linux host into Microsoft ActiveDirectory network.
The GNU Linux distribution used in the example is Ubuntu 14.10.

(The instructions on other distributions or version of Ubuntu system should be more or less the same)

Integration steps 

1. Set the hostname of the linux box and be sure it is *unique* in ActiveDirecory domain, i.e. there no any computer in the network with the same name
$ sudo gedit /etc/hostname
An example of hostname is DOMAIN-XX, where is XX can be some number # Set the fully qualified domain name of your host i.e. FQDN
$ sudo gedit /etc/hosts
Add following line on the top of the hosts file       DOMAIN-XX.domain.local DOMAIN-XX
# Restart the hostname service
$ sudo service hostname restart
# Check if the hostname and FQDN are set correctly
$ hostname
this should output
# And FQDN
hostname -f
this should output
# Download powerbroker tool from here # Set a permission to execute it with
$ sudo chmod a+x
# Install downloaded tools
$ sudo ./.sh
# Join to ActiveDirectory with following command
$ sudo domainjoin-cli join domain.local user-name@domain.local
*NOTE* that here the user-name here is a registered user in ActiveDirectory which has privileges to add a host to ActiveDirectory domain Normally all employee users in network have such privileges, if not consult to ActiveDirectory Administrator to get it. *+Possible errors+* * If you are getting an error like this
Error: DNS_ERROR_BAD_PACKET [code 0x0000251e]
A bad packet was received from a DNS server. Potentially the requested address
does not exist.
Note that starting from Ubuntu 14.04 NetworkManager has a local resolver which needs to be disabled
$ sudo gedit /etc/NetworkManager/NetworkManager.conf
like this
Configure dns server with resolvconf
$ sudo gedit /etc/resolvconf/resolv.conf.d/base
And add following content into it
domain domain.local
search domain.local
Update resolvconf with
$ sudo resolvconf -u
And restart network manager service
$ sudo service network-manager restart
After this you'll be able to
$ ping domain.local
* If you are getting an error like this
Error: ERROR_ACCESS_DENIED [code 0x00000005]
Access is denied 
This error can be because of two reasons Be sure that the hostname you are trying to add to ActiveDirecotory does not exist already Be sure that the user you are using for joining has sufficient privileges for adding a host in domain (consult to ActiveDirectory administrator) * Finally after joining successfully following will be printed

Update ActiveDirectory with new host info 

 After joining to ActiveDirecotry run following commands to update ActiveDirectory with the information about the new host i.e. DNS entry, NTP etc.
$ sudo /opt/pbis/bin/config UserDomainPrefix domain
$ sudo /opt/pbis/bin/config AssumeDefaultDomain true
$ sudo /opt/pbis/bin/config LoginShellTemplate /bin/bash
$ sudo /opt/pbis/bin/ad-cache --delete-all
$ sudo /opt/pbis/bin/update-dns
restart computer
$ sudo restart

Adding specific user into sudoers list 

ActiveDirectory domain users are just like local users on Ubuntu system, so if you want to make a specific user as "root" modify
$ sudo gedit /etc/sudoers
add following line into it
DOMAIN\\max.musternam ALL=(ALL) ALL
where max.musterman is a user from ActiveDirectory Domain h1. Allowing ActiveDirectory user login to Ubuntu To allow ActiveDirectory users to login into Ubuntu system ligthdm (display manager of Ubuntu system) needs to be configured
$ sudo gedit /etc/lightdm/lightdm.conf
Add following lines into lightdm configuration file
restart lightdm
$ sudo service lightdm restart

Possible issue related ignorance of settings in /etc/hosts

To avoid possible ignorance of settings in /etc/hosts file modify
$ sudo gedit /etc/nsswitch.conf 
be sure that it has following line
hosts:          files dns

Logging in

Restart your Ubuntu host and in the login screen type your ActiveDirectory username preceded with domain name DOMAIN e.g.
and use your ActiveDirectory user password to log in

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