Installing Samba4 As An Active Directory Domain Controller On CentOS 6

With the last version of samba 4 comes with Active directory logon and administration protocols, including typical active directory support and full interoperability with Microsoft Active Directory servers. This is possible with the combination of a LDAP directory, kerberos authentication, BIND DNS server and the remote procedure calls RPC.

When running as an Active Directory DC, you only need to run 'samba' (not smbd/nmbd/winbindd), as the required services are co-coordinated by this master binary. The tool to administer the Active Directory services is called 'samba-tool'.

I have a CentOS 6 x86_64 Minimal install. This post covers the initial installation and configuration of samba 4 as Active Directory domain controller on Centos 6 using BIND 9 as DNS backend and NTP server used by the clients.

1) Disable SELinux
[root@ad ~]# vi /etc/sysconfig/selinux
             selinux=disabled

 2) Install the pre-requisites (or dependencies) for Samba 4 installation
[root@ad ~]# yum -y install wget gcc make wget python-devel gnutls-devel openssl-devel libacl-devel krb5-server krb5-libs krb5-workstation bind bind-libs bind-utils ntp

3) Configure NTP to use the local time server
[root@ad ~]# vi /etc/ntp.conf
Comment line numbers 22,23,24 and uncomment the below lines in the configuration file
server  127.127.1.0     # local clock
fudge   127.127.1.0 stratum 10

4) Download and compile Samba 4 from the following link
[root@ad ~]# wget ftp://ftp.samba.org/pub/samba/samba-4.1.0.tar.gz
[root@ad ~]# tar -xvzf samba-4.1.0.tar.gz
[root@ad ~]# cd samba-4.1.0
[root@ad samba-4.1.0]# ./configure --enable-selftest --enable-debug
[root@ad samba-4.1.0]# make
[root@ad samba-4.1.0]# make install

5) Configuring Samba 4 to be a domain controller using samba-tool command
[root@ad ~]# /usr/local/samba/bin/samba-tool domain provision
Realm [ITGURUINDIA.COM]: ITGURUINDIA.COM       (All Caps) 
Domain [ITGURUINDIA]:
Server Role (dc, member, standalone) [dc]:
DNS backend (SAMBA_INTERNAL, BIND9_FLATFILE, BIND9_DLZ, NONE) [SAMBA_INTERNAL]: BIND9_DLZ
DNS forwarder IP address (write 'none' to disable forwarding) [192.168.124.252]: none
Administrator password: secret!1234
Retype password: secret!1234
Looking up IPv4 addresses
Looking up IPv6 addresses
No IPv6 address will be assigned
Setting up secrets.ldb
Setting up the registry
Setting up the privileges database
Setting up idmap db
Setting up SAM db
Setting up sam.ldb partitions and settings
Setting up sam.ldb rootDSE
Pre-loading the Samba 4 and AD schema
Adding DomainDN: DC=itguruindia,DC=com
Adding configuration container
Setting up sam.ldb schema
Setting up sam.ldb configuration data
Setting up display specifiers
Modifying display specifiers
Adding users container
Modifying users container
Adding computers container
Modifying computers container
Setting up sam.ldb data
Setting up well known security principals
Setting up sam.ldb users and groups
Setting up self join
Adding DNS accounts
Creating CN=MicrosoftDNS,CN=System,DC=itguruindia,DC=com
Creating DomainDnsZones and ForestDnsZones partitions
Populating DomainDnsZones and ForestDnsZones partitions
Setting up sam.ldb rootDSE marking as synchronized
Fixing provision GUIDs
A Kerberos configuration suitable for Samba 4 has been generated at /usr/local/samba/private/krb5.conf
Once the above files are installed, your Samba4 server will be ready to use
Server Role:           active directory domain controller
Hostname:              ad
NetBIOS Domain:        ITGURUINDIA
DNS Domain:            itguruindia.com
DOMAIN SID:            S-1-5-21-3335388306-1463729434-941727365

6) Configuring BIND as Samba Active Directory backend
Note: Bind must be installed on the same machine as Samba 4 is installed.
The dns backend BIND9_DLZ uses Samba 4 AD to store zone information
[root@ad ~]# rndc-confgen -a -r /dev/urandom
wrote key file "/etc/rndc.key"

A DNS keytab file was automatically created during provisioning/updating. Add the following' tkey-gssapi-keytab' option to the 'options' section of named.conf file. 
[root@ad ~]# vim /etc/named.conf
options {
listen-on port 53 { 192.168.1.100; };
allow-query { any; };
tkey-gssapi-keytab "/usr/local/samba/private/dns.keytab";
};
include "/usr/local/samba/private/named.conf";
include "/etc/rndc.key";

6) Change the resolv.conf file to the IP address of Samba server
[root@ad ~]# vim /etc/resolv.conf
domain Iitguruindia.com
nameserver 192.168.1.100

7) Configure the kerberos configuration file as below
[root@ad ~]# cp /usr/local/samba/share/setup/krb5.conf /etc/krb5.conf
[root@ad ~]# vim /etc/krb5.conf
[libdefaults]
        default_realm = ITGURUINDIA.COM    (All Caps)
        dns_lookup_realm = false
        dns_lookup_kdc = true

8) Set the permissions for named on the below files
[root@ad ~]# chgrp named /etc/krb5.conf
[root@ad ~]# chown named:named /usr/local/samba/private/dns 
[root@ad ~]# chown named:named /usr/local/samba/private/dns.keytab
[root@ad ~]# chmod 775 /usr/local/samba/private/dns

9) Configuring the Samba 4 init.d script and set permissions to it.
[root@ad ~]# vim /etc/init.d/samba4
#! /bin/bash
#
# samba4 Bring up/down samba4 service
#
# chkconfig: - 90 10
# description: Activates/Deactivates all samba4 interfaces configured to
# start at boot time.
#
### BEGIN INIT INFO
# Provides:
# Should-Start:
# Short-Description: Bring up/down samba4
# Description: Bring up/down samba4
### END INIT INFO
# Source function library.
. /etc/init.d/functions

if [ -f /etc/sysconfig/samba4 ]; then
. /etc/sysconfig/samba4
fi

CWD=$(pwd)
prog="samba4"

start() {
# Attach irda device
echo -n $"Starting $prog: "
/usr/local/samba/sbin/samba
sleep 2
if ps ax | grep -v "grep" | grep -q /samba/sbin/samba ; then success $"samba4 startup"; else failure $"samba4 startup"; fi
echo
}
stop() {
# Stop service.
echo -n $"Shutting down $prog: "
killall samba
sleep 2
if ps ax | grep -v "grep" | grep -q /samba/sbin/samba ; then failure $"samba4 shutdown"; else success $"samba4 shutdown"; fi
echo
}
status() {
/usr/local/samba/sbin/samba --show-build
}

# See how we were called.
case "$1" in
start)
start
;;
stop)
stop
;;
status)
status irattach
;;
restart|reload)
stop
start
;;
*)
echo $"Usage: $0 {start|stop|restart|status}"
exit 1
esac

exit 0

[root@ad ~]# chmod 755 /etc/init.d/samba4

10) Configure  the services to start at boot and start the below services.
[root@ad ~]# chkconfig ntpd on
[root@ad ~]# chkconfig named on
[root@ad ~]# chkconfig samba4 on
[root@ad ~]# service ntpd start
[root@ad ~]# service named on
[root@ad ~]# service samba4 on

11) If iptables is enabled then the below ports need to allowed through firewall.
[root@ad ~]# iptables -A INPUT -p udp -i eth0 -s 192.168.1.0/24 --dport 53 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p udp -i eth0 -s 192.168.1.0/24 --dport 123 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p udp -i eth0 -s 192.168.1.0/24 --dport 135 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p udp -i eth0 -s 192.168.1.0/24 --dport 138 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p udp -i eth0 -s 192.168.1.0/24 --dport 389 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p tcp -i eth0 -s 192.168.1.0/24 --dport 88 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p tcp -i eth0 -s 192.168.1.0/24 --dport 139 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p tcp -i eth0 -s 192.168.1.0/24 --dport 389 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p tcp -i eth0 -s 192.168.1.0/24 --dport 445 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p tcp -i eth0 -s 192.168.1.0/24 --dport 464 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p tcp -i eth0 -s 192.168.1.0/24 --dport 636 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p tcp -i eth0 -s 192.168.1.0/24 --dport 1024:1032 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p tcp -i eth0 -s 192.168.1.0/24 --dport 3268 -j ACCEPT
[root@ad ~]# iptables -A INPUT -p udp -i eth0 -s 192.168.1.0/24 --dport 3269 -j ACCEPT

[root@ad ~]# service iptables save

12) Reboot the system to check services are working after reboot are not.
[root@ad ~]# reboot

13) Join a Windows PC to this domain controller 

14) Troubleshooting incase debugging dynamic DNS updates are not working
[root@ad ~]# /usr/local/samba/sbin/samba_dnsupdate --verbose --all-names

15) Port numbers used in iptables and their use.
53 - UDP - DNS (Domain Naming System)
123 - UDP - NTP (Network Time Protocol)
135 - UDP - RPC (Remote Procedure Calls)
138 - UDP - NetBIOS Logon
389 - UDP - LDAP UDP (LightWeight Directory Access Protocol)
88 - TCP - Kerberos 
139 - TCP - NetBIOS Session
389 - TCP - LDAP TCP (LightWeight Directory Access Protocol)
445 - TCP - SMB CIFS (Server Message Block / Common Internet File System)
464 - TCP - Kerberos Password Management 
636 - TCP - LDAP SSL (LightWeight Directory Access Protocol)
3268 - TCP - LDAP Global Catalog 
3269 - TCP - LDAP Global Catalog SSL