Openmediavault: join a Windows 2008R2 domain


Domain is : domain.local
windows 2008R2 hostname : srv-dc-01
omv hostname : omv

Check IP configuration

Openmediavault has a DHCP assigned IP address. You should check its hostname and name resolution

omv:/# host domain.local
domain.local has address
omv:/# hostname -f

Check time and NTP

The LAB environment runs ESXi : time is synced on each VM boot and is sufficient for testing purpose. In production environment use VMware Tools and time sync agains the ESXi host or use NTP.

Install required packages

apt-get update
apt-get install krb5-user krb5-clients libpam-krb5 winbind libnss-winbind

You will asked for kerberos default domain : DOMAIN.LOCAL

Kerberos configuration

Runs out of the box with default configuration. However you may edit /etc/krb5.conf as the following

        default_realm = DOMAIN.LOCAL
        ticket_lifetime = 600
        dns_lookup_realm = yes
        dns_lookup_kdc = yes
        renew_lifetime = 7d
;       allow_weak_crypto = true

# The following krb5.conf variables are only for MIT Kerberos.
;       krb4_config = /etc/krb.conf
;       krb4_realms = /etc/krb.realms
;       kdc_timesync = 1
;       ccache_type = 4
;       forwardable = true
;       proxiable = true

# The following encryption type specification will be used by MIT Kerberos
# if uncommented.  In general, the defaults in the MIT Kerberos code are
# correct and overriding these specifications only serves to disable new
# encryption types as they are added, creating interoperability problems.
# Thie only time when you might need to uncomment these lines and change
# the enctypes is if you have local software that will break on ticket
# caches containing ticket encryption types it doesn't know about (such as
# old versions of Sun Java).

      # Pour Windows Server 2008 R2 (seems not required)
;      default_tgs_enctypes = aes256-cts-hmac-sha1-96 rc4-hmac des-cbc-crc des-cbc-md5
;      default_tkt_enctypes = aes256-cts-hmac-sha1-96 rc4-hmac des-cbc-crc des-cbc-md5
;      permitted_enctypes = aes256-cts-hmac-sha1-96 rc4-hmac des-cbc-crc des-cbc-md5

      # Pour Windows Server 2003 (not tested agains windows 2003 server yet, and this server is deprecated)
;      default_tgs_enctypes = rc4-hmac des-cbc-crc des-cbc-md5
;      default_tkt_enctypes = rc4-hmac des-cbc-crc des-cbc-md5
;      permitted_enctypes = rc4-hmac des-cbc-crc des-cbc-md5

        profile = /etc/krb5kdc/kdc.conf

        kdc = FILE:/var/log/krb5kdc.log
        admin_server = FILE:/var/log/kadmin.log
        default = FILE:/var/log/krb5lib.log

Test kerberos settings

kinit -V administrator (at) DOMAIN.LOCAL

Give administrator password

Test you got a ticket: klist

Ticket cache: FILE:/tmp/krb5cc_0
Default principal: administrator (at) DOMAIN.LOCAL
Valid starting     Expires            Service principal
01/28/13 13:28:58  01/28/13 13:38:58  krbtgt/DOMAIN.LOCAL (at) DOMAIN.LOCAL

Destroy all tickets (and check with klist): kdestroy

SAMBA settings

In OMV webGUI :
enable SAMBA
set Workgroup : DOMAIN
tick “Enable user home directories”. You may also tick “Set browseable”.
add extra options :

password server = *
security = ads
allow trusted domains = no
idmap config * : range = 9400-59999
winbind use default domain = true
winbind offline logon = false
winbind enum users = yes
winbind enum groups = yes
winbind separator = /
winbind nested groups = yes
;winbind normalize names = yes
winbind refresh tickets = yes
template shell = /bin/bash
template homedir = /home/%U

#  Performance improvements
socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
client ntlmv2 auth = yes
client use spnego = yes

Test samba configuration: testparm

This step is not required

If you wish to view your AD users and groups in OMV webinterface include UIDs and GIDs into non-system users and groups in /etc/login.defs. Find UID_MAX and change UID_MAX and GID_MAX as the following

UID_MAX                 60000
GID_MAX                 60000

Editing AD users and groups using the OMV webinterface will fail because they are not stored in /etc/passwd and /etc/group.

Join the domain

Argument createcomputer allows you to create the computer’s account in an organisational unit (OU) and is not required.

omv:/# net ads join -U administrator createcomputer=servers/linux
Enter administrator's password:
Using short domain name -- DOMAIN
Joined 'OMV' to realm 'domain.local'

Enable authentication with winbind

edit /etc/nsswitch.conf

passwd: compat winbind 
shadow: compat
group: compat winbind

Enable authentication with winbind

edit /etc/nsswitch.conf

passwd: compat winbind 
shadow: compat
group: compat winbind

Check users and groups enumeration

getent passwd (you get local and AD users lists)
getent group (you get local and AD groups lists)

Enable mkhomedir and umask

create the file /usr/share/pam-configs/my_mkhomedir with the following content

Name: Activate mkhomedir
Default: yes
Priority: 900
Session-Type: Additional
	required umask=0077 skel=/etc/skel

umask argument for mkhomedir didn’t worked for me. seems be a better option. Create the file /usr/share/pam-configs/umask with the following

Name: Activate umask
Default: yes
Priority: 800
Session-Type: Additional
	optional umask=0077

Fix domain folder permission

In SMB/CIFS, extra confguration the special variable %D is used to distinguish domain users from OMV’s local users. A folder will becreated upon first domain user connexion. However the folder will not allow domain users to traverse the folder and access their home directory. This need a fix. Create the folder where template homedir expects to find it, and adjust the owners and permissions. If your active directory contains a white space, ensure to escape it with a backslash.

mkdir /home/DOMAIN
chmod 0755 /home/DOMAIN
chown root:domain\ users DOMAIN

SSH login for AD users

In OMV webGUI enable SSH, disable root login (prefer su and sudo) and add this in Extra Options :

AllowGroups root ssh "domain users"

Please check “domain users is enclosed by double quotes and check this is the group name available in windows 2008 R2 (I’m french and I’m using a french windows 2008R2 : groups and users names are localized)

Login against SMB or SSH

don’t prefix username with domain. (eg: not DOMAIN.LOCAL/administrator; use administrator only)

2016   domain   krb   linux   openmediavault   samba   windows