ActiveDirectory - UCC Wiki

This page describes the current (2019) Active Directory configuration at UCC.

The Active Directory (AD) domain at UCC is ad.ucc.gu.uwa.edu.au with the NETBIOS domain name UCCDOMAYNE. The primary Domain Controller (DC) samson.ucc.gu.uwa.edu.au which also serves authoritative DNS for ad.ucc.gu.uwa.edu.au.

For some background on why the Standard Operating Environment does what it does, see NewActiveDirectory. For outdated documentation and some info about the migration from the old LDAP domain, see OldActiveDirectory.

This page describes how to configure Linux systems to connect to an Active Directory domain as the database for users and groups.

Contents

Windows
Linux
OpenLDAP

Windows

Assumed you are using Windows 10.

Open File Explorer, right click on My PC and select Properties. You might need to click the rename (advanced) option on the rightmost pane of the window.
Under the Computer Name tab, select Change... and enter ad.ucc.gu.uwa.edu.au as the domain. Make sure the computer name is also correct, change it if necessary (Windows 10 generates a random name when you install it).
When you click OK, enter a UCC wheel username/password (aka someone who has domain admin permissions). Restart the computer at your convenience.
Congratulations, you have joined a computer to the domain.

Linux

Configuring SSSD

Full section and alternative client configurations: https://wiki.ucc.asn.au/NewActiveDirectory/LinuxClients

There is a very informative Red Hat article about configuring sssd manually. The following instructions are a functional adaptation. For a more detailed understanding of what these config files and options mean, please start by reading the manpages for sssd, sssd-ad, sssd-krb5, sssd-ldap, sssd.conf, krb5.conf and smb.conf and the above article.

These instructions are confirmed working on Linux Mint 19.1 (Tara), using sssd version 1.16.1 and samba-common-bin package version 4.7.6.

Install the necessary packages and uninstall any conflicting ones:

apt -y install samba-common-bin samba-dsdb-modules sssd sssd-ad sssd-krb5 sssd-ldap sssd-tools krb5-user krb5-doc libpam-sss libnss-sss adcli libsasl2-modules-gssapi-mit
apt -y purge winbind realmd libpam-krb5 libpam-ldap libpam-winbind libnss-ldap libnss-winbind

Remove any configuration files if they exist and stop services:

mv /etc/samba/smb.conf /etc/samba/smb.conf.old
mv /etc/nsswitch.conf /etc/nsswitch.conf.old
rm /etc/krb5.conf /etc/krb5.keytab /etc/sssd/sssd.conf
systemctl stop sssd winbind samba-ad-dc smbd nmbd

Install the configs semi-automatically:

wget -O /tmp/ucc-ad-config.tar.gz https://www.ucc.asn.au/ucc-ad-config.tar.gz && tar -C / -xvzf /tmp/ucc-ad-config.tar.gz

Run pam-auth-update and check that SSS authentication is enabled and that winbind authentication (if present) is disabled.
Create the machine account in AD and produce a keytab for sssd containing the machine account credentials. If using a user other than Administrator, ensure they have sufficient privileges to join a machine to the domain.
```
rm /etc/krb5.keytab
kinit <wheel username here>
net ads join --no-dns-updates -k
# verify the machine account credentials are in the keytab:
klist -k
```
Start the necessary services:
```
systemctl restart sssd
```
Verify that you can see the correct user and group info using getent passwd and getent group respectively. The output format is equivalent to the /etc/passwd and /etc/group files.

Diagnostics

Sometimes group memberships don't seem to be updated, this can often be fixed by clearing the cache:

sss_cache -E if using sssd
net cache flush if using winbind
Or if the above fails to have an effect, try rejoining to the domain using the instructions below.

You can edit things with

kinit; ldapvi -b dc=ad,dc=ucc,dc=gu,dc=uwa,dc=edu,dc=au --host AD.UCC.GU.UWA.EDU.AU -Y GSSAPI

or more easily with

samba-tool user edit <username>

Config file examples

These should be the same as in the config package (https://www.ucc.asn.au/ucc-ad-config.tar.gz but here they are in case something gets broken or that archive goes missing.

/etc/sssd/sssd.conf

[sssd]
config_file_version = 2
domains = ad.ucc.gu.uwa.edu.au
services = nss, pam, pac

# domain configuration: see manpages sssd.conf, sssd-ldap, sssd-krb5 and sssd-ad
# see https://access.redhat.com/articles/3023951
# needs correct configution for: /etc/nsswitch.conf /etc/samba/smb.conf /etc/resolv.conf `pam-auth-update`
[domain/AD.UCC.GU.UWA.EDU.AU]
enumerate = true
id_provider = ad
auth_provider = ad
chpass_provider = ad
access_provider = ad
ldap_id_mapping = false

cache_credentials = true
# if you want to use a custom CA certificate for AD
#ldap_tls_cacert = /etc/sssd/ucc-ad-ca.cer
# or just allow invalid (self-signed) certificates
ldap_tls_reqcert = allow

# allow local users to be included in AD groups
ldap_rfc2307_fallback_to_local_users = true

/etc/nsswitch.conf

# /etc/nsswitch.conf

passwd:         compat systemd sss
group:          compat systemd sss
shadow:         compat sss
gshadow:        files

hosts:          files mdns4_minimal [NOTFOUND=return] dns myhostname
networks:       files

protocols:      db files
services:       db files sss
ethers:         db files
rpc:            db files

netgroup:       nis sss

/etc/krb5.conf

[libdefaults]
    default_realm = AD.UCC.GU.UWA.EDU.AU
    dns_lookup_realm = true
    dns_lookup_kdc = true
    rdns = false
    ticket_lifetime = 24h
    renew_lifetime = 7d
    forwardable = yes

/etc/samba/smb.conf

[global]
        realm = AD.UCC.GU.UWA.EDU.AU
        workgroup = UCCDOMAYNE
        security = ads
        client signing = mandatory
        client use spnego = yes
        tls enabled = yes
        kerberos method = secrets and keytab
        dedicated keytab file = /etc/krb5.keytab
        log file = /var/log/samba/%m.log

OpenLDAP

If for some reason you need to authenticate using our AD over OpenLDAP (e.g. OpenVPN or Octoprint), you will need two things to actually talk LDAP to samson.

The UCC-CA certificate, and a custom OpenLDAP config file.

The cert is available from the main website at the top, or from /etc/ssl/certs on most of the main servers.

/etc/ldap/ldap.conf

        URI ldaps://samson.ad.ucc.gu.uwa.edu.au
        BASE dc=ad,dc=ucc,dc=gu,dc=uwa,dc=edu,dc=au

        SSL on
        TLS_REQCERT allow
        TLS_CACERT /etc/ssl/certs/UCC-CA.crt

Once you have both of these, both ldapsearch and actual LDAP calls will actually contact samson properly.

Also use ldaps://ad.ucc.gu.uwa.edu.au to talk to it.