Linux:Samba AD Factory

To use Samba as an Active Directory Domain Controller, Samba must be built from source. While various RPM distros have been made available in the past (and continue to do so today), relying upon these for continued support of these build packages is an operational hazard. Instead, KitsNet has a formalized process to operate a Samba AD "Factory", where source kits will be downloaded and built into binaries under the /usr/local/samba directory tree. The resulting binary tree will be packaged into a tarball and subsequently deployed to the Active Directory Domain Controllers for the knada.lan.kitsnet.us domain.

There is still an issue with serving time from the DCs. The answer will be found by going through https://wiki.samba.org/index.php/Time_Synchronisation

1 Build CentOS 8 / Rocky Linux 8 Base System for Factory

The Factory system is that which will be used to download Samba source kits to build a binary tree and resulting tarball. There will be one of these systems based on a basic Linux Virtual Server Guest with 1.5 GB RAM, 4 vCPU and two disks:

• T0 disk0 10 GB (V0uv### /tmp 1024 MB, /swap 512 MB, /boot 1 GB, and the rest for root)
• T3 disk1 16 GB (V3uv### /var 3 GB, /usr/local 13 GB)

The system will have a DHCP reservation as <new-guest>.lan.kitsnet.us. When running the Anaconda installer, add to Software Selection, Additional software for Selected Environment: Development Tools .

2 Build CentOS 8 / Rocky Linux 8 Base System for Samba AD DC

The Samba AD DC systems are those running Samba as Active Directory Domain Controllers for the knada.lan.kitsnet.us domain. There will be at least two of these systems, each based on a basic Linux Virtual Server Guest with 1.5 GB RAM, 2 vCPU and two disks:

• T0 disk0 14 GB (V0uv### /tmp 512 MB, /swap 3 GB, /boot 1 GB, root 7 GB)
• T3 disk1 4 GB (V3uv### /var 2 GB)

Since these system will be domain-joined, it is important that they have a DHCP reservation as <new-guest>.knada.lan.kitsnet.us.

2.1 Environment Customization

2.1.1 path

• add /usr/local/samba/bin and /usr/local/samba/sbin to:
  • secure_path in /etc/sudoers
  • PATH in /etc/crontab
  • PATH in /etc/anacrontab
• carefully add /usr/local/samba/sbin and /usr/local/samba/bin appropriately (check order) to PATH in /etc/csh.login
• add /usr/local/samba/sbin to pathmunge in /etc/profile:

if [ "$EUID" = "0" ]; then
    pathmunge /usr/sbin
    pathmunge /usr/local/sbin
    pathmunge /usr/local/samba/sbin
    pathmunge /usr/local/samba/bin after
else
    pathmunge /usr/local/sbin after
    pathmunge /usr/sbin after
    pathmunge /usr/local/samba/sbin after
    pathmunge /usr/local/samba/bin
fi

2.1.2 Firewall

# firewall-cmd --set-default-zone=internal
# firewall-cmd --zone=internal --change-interface ens3 --permanent
# firewall-cmd --add-service={dns,ldap,ldaps,kerberos} --permanent
# firewall-cmd --add-port={389/udp,135/tcp,135/udp,138/udp,138/tcp,137/tcp,137/udp,139/udp,139/tcp,445/tcp,445/udp,3268/udp,3268/tcp,3269/tcp,3269/udp,49152/tcp,49153/tcp,49154/tcp} --permanent
# firewall-cmd --reload

2.1.2.1 Port Reference

• 88=kerberos
• 135=epmap
• 137=netbios-ns
• 138=netbios-dgm
• 139=netbios-ssn
• 389=ldap
• 445=microsoft-ds
• 464=kpasswd
• 636=ldaps
• 3268=msft-gc

• 3269=msft-gc-ssl

2.1.3 Backup

Copy backup_samba-ad-dc to /usr/local/sbin/

# mkdir /var/lib/samba-ad-dc_backup
# chgrp kitsnet_adm  /var/lib/samba-ad-dc_backup
# chmod o-rx /var/lib/samba-ad-dc_backup

2.1.4 rsyslog

Add to end of /etc/rsyslog.conf the line *.* @192.168.15.80:514

# systemctl restart rsyslog.service
# systemctl enable rsyslog.service

3 Setup Server to Build or Run Samba AD DC

Complete the preparations documented in Setting up Samba as an Active Directory Domain Controller

3.1 Factory Build Server Packages

Refer to Package Dependencies Required to Build Samba and incorporate the Manually maintained Distribution-specific Package lists and the Red Hat Enterprise Linux 8 / CentOS 8 section. It will also be necessary to dnf install dbus-devel python3-markdown

3.2 Samba AD DC Server Packages

# dnf install avahi-libs cups-libs python3-markdown patch pam-devel python3-cryptography python3-dns krb5-workstation libtasn1-tools 
# dnf install lmdb-devel
# mkdir /usr/local/samba

3.3 Check Filesystem Support on all Servers

Refer to File System Support for details KistNet standard is for using xfs, so there is only one option to check for:

# uname -r
4.18.0-240.22.1.el8_3.x86_64
# grep -E "CONFIG_EXT4_FS_POSIX_ACL" /boot/config-4.18.0-240.22.1.el8_3.x86_64
CONFIG_EXT4_FS_POSIX_ACL=y

Install the attr package with dnf install attr. Next, refer to the Testing your filesystem section of the documentation for the verification steps

4 Download Samba Source to Factory Build Server

• Create the base of the Factory source directory structure

# mkdir /usr/local/SambaAD-Factory
# chown psmode:kitsnet_adm /usr/local/SambaAD-Factory

• Check https://download.samba.org/pub/samba/stable/ to identify the latest *.tar.gz and wget that file
• tar -xzvf the downloaded file with -C /usr/local/SambaAD-Factory

5 Build Samba AD DC Factory Distribution

Enter the version-specific directory under /usr/local/SambaAD-Factory

$ ./configure --mandir=/usr/local/samba/man
$ make uninstall
$ du /usr/local/samba
0 /usr/local/samba/etc
0 /usr/local/samba/var/lib
0 /usr/local/samba/var/locks
0 /usr/local/samba/var/cache
0 /usr/local/samba/var/lock
0 /usr/local/samba/var/run
0 /usr/local/samba/var
0 /usr/local/samba/private
0 /usr/local/samba/bind-dns
0 /usr/local/samba/
$ make -j 8
$ rm -R /usr/local/samba/*
$ make -j 8 install
$ cd ../dist
$ tar czf samba-4.14.3-factory.tar.gz --owner=root -C /usr/local samba
$ tar --list --verbose --file samba-4.14.3-factory.tar.gz

6 Deploy Samba AD DC Factory Distribution on AD DC

On initial deploy only, use:

$ sudo tar xvf samba-4.14.3-factory.tar.gz -C /usr/local/

on all updates after that, use:

$ sudo tar xvf samba-4.14.3-factory.tar.gz -C /usr/local/ --exclude="samba/bind-dns" --exclude="samba/etc" --exclude="samba/private" --exclude="samba/var"

• check for knada.lan.kitsnet.us to end of search line in /etc/resolv.conf
• test DNS and SRV record resolution per Linux and Unix DNS Configuration
• Verify the server is ready per the steps in Preparing the Host for Joining the Domain
• copy /usr/local/samba/share/setup/krb5.conf to /etc/krb5.conf and modify to:

[libdefaults]
    default_realm = KNADA.LAN.KITSNET.US
    dns_lookup_realm = false
    dns_lookup_kdc = true
    dns_lookup_kdc = true

[realms]
KNADA.LAN.KITSNET.US = {
    default_domain = knada.lan.kitsnet.us
}

#[domain_realm]
#   ${HOSTNAME} = KNADA.LAN.KITSNET.US

• Initialize Kerberos with

# kinit administrator
# klist

7 Join to Active Directory as a Domain Controller

# script join-kitsnet.log
# samba-tool domain join knada.lan.kitsnet.us DC -k yes --option='idmap_ldb:use rfc2307 = yes'

If log output directs it, cp /usr/local/samba/private/krb5.conf /etc/

Information about ID mapping is available at https://wiki.samba.org/index.php/Identity_Mapping_Back_Ends and https://wiki.samba.org/index.php/Idmap_config_ad. It appears from walker's smb.conf that we have: idmap_ldb:use rfc2307 = yes

Add to /usr/local/samba/etc/smb.conf in the [global] section:

dns forwarder = 192.168.15.1
time server = yes

Then:

# sudo smbcontrol all reload-config
# sudo samba

The last command will trigger samba startup. Until this is done, samba-tool drs showrepl will show cryptic, scary error messages.

To trigger RID block creation on the new Domain Controller sudo samba-tool user create <new-user> --given-name "Silly" --surname "Person"

7.1 Managing Samba Service on the AD DC

Refer to Managing the Samba AD DC Service Using Systemd for how to add Samba to systemctl

7.2 Transferring FSMO Roles

See Transferring and Seizing FSMO Roles for background on FSMO roles and management. Note that when transferring domaindns and forestdns roles, add -U administrator to end of the command:

# samba-tool fsmo transfer --role=forestdns -U administrator

7.3 Advertise AD DC as DNS Server

On radix.kitsnet.us update the file /etc/config/dhcp in the config dnsmasq section to add a line for the new DC:

        list server '/knada.lan.kitsnet.us/192.168.15.84'

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