Back in 2004, we had limited options for Active Directory integration with Linux. Fast forward to 2014, the landscape has significantly changed with Microsoft deprecating older methods and Red Hat pushing new solutions. Here's what I've observed about the current state:

# Common integration methods circa 2014:
1. Winbind/Samba (traditional but problematic)
2. Native LDAP/Kerberos (manual configuration)
3. SSSD (Red Hat's recommended path)
4. Commercial solutions (Centrify/Powerbroker)

The old approach using Microsoft's Identity Management for Unix (IdMU) role had several advantages:

• GUI-based user attribute management
• Simple POSIX attribute synchronization
• NIS server compatibility

But with Windows Server 2012 R2, Microsoft clearly marked this as deprecated. The official statement is clear:

"The Server for Network Information Service (NIS) Tools option of Remote Server Administration Tools (RSAT) is deprecated. Use native LDAP, Samba Client, Kerberos, or non-Microsoft options."

For RHEL/CentOS environments, SSSD (System Security Services Daemon) has become the gold standard. Here's a basic configuration example:

# /etc/sssd/sssd.conf
[sssd]
config_file_version = 2
services = nss, pam
domains = example.com

[domain/example.com]
id_provider = ad
access_provider = ad
ad_server = dc1.example.com,dc2.example.com
ad_domain = example.com
krb5_realm = EXAMPLE.COM
cache_credentials = True

Key benefits of SSSD:

• Better memory management than NSLCD
• Offline authentication support
• Integrated with Kerberos
• Active development (unlike Winbind)

While SSSD works well for most cases, commercial products like Centrify and Powerbroker (formerly Likewise) still have their place:

# Centrify basic join command
adjoin -w -V example.com -u admin

Consider commercial options when you need:

• Group Policy Object (GPO) enforcement
• Advanced auditing capabilities
• Enterprise support contracts

With Windows 2008 R2 Core systems, you can't install the deprecated IdMU components. Here's how to manage user attributes without them:

# Using ldapmodify to set Unix attributes
dn: CN=jsmith,OU=Users,DC=example,DC=com
changetype: modify
add: uidNumber
uidNumber: 10001
-
add: gidNumber
gidNumber: 10001
-
add: unixHomeDirectory
unixHomeDirectory: /home/jsmith
-
add: loginShell
loginShell: /bin/bash

In production environments, I've observed these performance characteristics:

Method	Auth Latency	Resource Usage	Stability
Winbind	High	High	Medium
SSSD	Low	Medium	High
Centrify	Medium	Low	High

For environments moving from NSLCD or Winbind to SSSD, here's a safe migration approach:

# 1. Install SSSD while keeping old config
yum install sssd authconfig

# 2. Test SSSD configuration in parallel
authconfig --enablesssd --enablesssdauth --enablemkhomedir --update

# 3. Gradually shift services
systemctl stop nslcd
systemctl start sssd

# 4. Verify functionality before removing old packages
getent passwd aduser@domain

---

After a decade of wrestling with various AD-Linux integration methods (from the painful Winbind days to commercial solutions like Centrify), the landscape has finally stabilized around a few reliable approaches. Let's examine the current best practices.

The deprecated "Identity Management for Unix" role and unreliable Winbind implementations created significant challenges:

# Example of problematic Winbind config (now obsolete)
[global]
    workgroup = DOMAIN
    security = ads
    realm = DOMAIN.COM
    winbind use default domain = yes
    winbind enum users = yes
    winbind enum groups = yes

For RHEL6+ environments, SSSD (System Security Services Daemon) has become the gold standard:

# /etc/sssd/sssd.conf minimal working example
[sssd]
domains = example.com
services = nss, pam
config_file_version = 2

[domain/example.com]
id_provider = ad
access_provider = ad
ad_server = dc1.example.com,dc2.example.com
ad_domain = example.com
krb5_realm = EXAMPLE.COM
krb5_store_password_if_offline = True
cache_credentials = True

When working with Windows Server 2008 R2 Core or 2012 R2:

• Ensure proper time synchronization (chrony or ntpd)
• Configure DNS resolution properly
• Use realm join instead of manual configuration

# Joining a domain with realm
sudo realm join --user=adminuser example.com

For authentication problems, these commands are invaluable:

# Check Kerberos ticket
klist

# Test user resolution
getent passwd domainuser

# Verify SSSD operation
sssctl user-checks domainuser
journalctl -u sssd --no-pager -n 50

For enterprises requiring fine-grained access control:

# Adding access control in sssd.conf
[domain/example.com]
access_provider = simple
simple_allow_groups = linux_admins, dev_team
simple_allow_users = admin1, admin2

Transitioning from Winbind/NSLCD to SSSD:

1. Backup current configuration
2. Install SSSD packages
3. Test in parallel before cutover
4. Monitor for several days

For large environments:

# Performance tuning parameters
[domain/example.com]
ldap_idmap_range_size = 200000
ldap_idmap_default_range = 10000-199999
ldap_idmap_default_range = 200000-999999

• Enable Kerberos pre-authentication
• Implement proper firewall rules
• Regularly rotate keytabs
• Use GPOs to manage Linux policies where possible