Active Directory Federation Services (AD FS) enables single sign-on access to resources across organizational networks. It provides authentication using methods like forms, certificates, and Windows authentication. AD FS versions have been released with different Windows Server operating systems. Planning considerations for AD FS include network topology, high availability, certificates, and capacity. AD FS relies on security token services, and works with Azure Active Directory and password synchronization to provide federated access to cloud applications and resources.

1. Active Directory Federation Services
Thomas Stensitzki

2. AD FS | Quick Overview
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3. What is AD FS
 AD FS  Active Directory Federation Services
 AD FS provides the infrastructure that enables a user to authenticate in one network and
use a secure service or application in another network
 Authentication Methods
- Resources accessed from outside the corporate network
- Forms authentication
- Certificate authentication | Smart Card, Soft Certificate
- Resources accessed from inside the corporate network
- Windows Authentication
 Device authentication can provide a secondary authentication method when multi-factor
authentication (MFA) is required
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4. AD FS Versions
 AD FS 1.0 was originally released as a Windows component with Windows Server 2003 R2.
 AD FS 1.1 was released with Windows Server 2008 and Windows Server 2008 R2, as an
installable server role.
 AD FS 2.0 was released as an installable download for Windows Server 2008 SP2 or above.
 AD FS 2.1 was released with Windows Server 2012 as an installable server role.
 AD FS 3.0 is an installable server role on Windows Server 2012 R2. AD FS 3.0 does not
require a separate IIS install and it includes a new AD FS proxy role called the Web
Application Proxy.
 AD FS 4.0 released with Windows Server 2016
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5. How AD FS works
 Security token service (STS) infrastructure
- Active Directory Federation Services
- Shibboleth Identity Provider
- Third-Party Identity Providers
 AD FS and AAD Connect
- Account synchronization for federated domain users
 AAD Connect, Password Sync and AD FS
- AAD Connect w/o Password Sync does not store password hashes in Azure AD
 No failback, if AD FS is not available
- AAD Connect w/ Password Sync synchronizes password hash to Azure AD
 Convert federated domain to standard, if AD FS is not available
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6. Azure AD Federation Compatibility
- Optimal IDM Virtual Identity Server Federation
Services
- PingFederate 6.11, 7.2, 8.x
- Centrify
- IBM Tivoli Federated Identity Manager 6.2.2
- SecureAuth IdP 7.2.0
- CA SiteMinder 12.52
- RadiantOne CFS 3.0
- Okta
- OneLogin
- NetIQ Access Manager 4.0.1
- BIG-IP with Access Policy Manager BIG-IP
ver. 11.3x – 11.6x
- VMware Workspace Portal version 2.1
- Sign&go 5.3
- IceWall Federation Version 3.0
- CA Secure Cloud
- Dell One Identity Cloud Access Manager v7.1
- AuthAnvil Single Sign On 4.5
- Sailpoint IdentityNow Active Directory Federation
Services
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7. AD FS Planning Considerations (1)
 Preparation for end devices and browsers
 Placement of AD FS servers and proxies
 Appropriate internal network topologies for farms/proxies
 Check AD for non-supported characters, and invalid data
 Preparation of DNS host names records
 Purchase or issuing of certificates
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8. AD FS Planning Considerations (2)
 Configuration of firewalls for AD FS-related ports
- TCP 443
 Selection of appropriate AD FS database technology
- Windows Internal Database or SQL Server
 Capacity planning to determine required servers, and server specifications
- Number users to authenticate, number of relying party trusts
 Planning for AD FS High Availability
 Preparation for multifactor authentication
 Planning for access filtering using claims rules
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9. AD FS Clients
 Microsoft Online Services Sign-In Assistant
- Office 365 Desktop setup
- System Center Configuration Manager
- Manual install
 Modern Browsers with JScript
- Internet Explorer
- Mozilla Firefox
- Safari
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10. ADAL
 ADAL  Active Directory Authentication Library
 ADAL works with OAuth 2.0 to enable more authentication and authorization scenarios
 Utilizes AD FS Infrastructure
 Office 2016 clients support modern authentication by default
Link: How modern authentication works for Office 2013 and Office 2016 client apps
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11. AD FS Topologies (1)
 Stand-alone server versus server farm
- Always create a server farm, even with one server
 Windows Internal Database (WID) versus SQL Server
 Number of Servers
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1 - 100 Relying Party (RP) Trusts More than 100 RP Trusts
1 - 30 AD FS Nodes WID Supported WID not supported - SQL Required
More than 30 AD FS Nodes WID not supported - SQL Required WID not supported - SQL Required
Number of users Minimum number of servers (Source: Microsoft)
< 1.000 0 dedicated federation server, can co-locate on DC
0 dedicated federation server proxy, can co-locate on web server
1.000 – 15.000 2 dedicated federation servers
2 dedicated federation server proxies
15.000 – 60.000 3 – 5 dedicated federation servers
Min 2 dedicated federation server proxies

12. AD FS Topologies (2)
 AD FS Proxies
- Not mandatory but recommended for extranet/internet users
 Server Placement
- AD FS servers are domain joined are located in the internal network
- AD FS proxy servers should not be domain joined and are located in the perimeter network
fs.contoso.com
172.16.1.3
wap1.contoso.com
192.0.2.1
wap2.contoso.com
192.0.2.2
AD FS Proxies
Perimeter Network
fs.contoso.com
192.0.2.3
fs2.lan.contoso.com
172.16.1.2
Federation Server Farm
Internal Network
fs1.lan.contoso.com
172.16.1.1
fs.contoso.com
PUBLIC IP
Internal Users ExternalUsers

13. AD FS Requirements (1)
 Active Directory
- Domain controllers running Windows Server 2008 or later
- Windows Server 2016 domain controller for Microsoft Passport
- Account domain and AD FS server domain must be operating at DFL Windows Server 2003
- User account client certificate authentication requires DFL Windows Server 2008
- Check on-premises Active Directory for UPN domain
- Remediate UPN for invalid characters
 DNS and namespaces
- Namespace planning, e.g. sts, fs or adfs
- All clients must be able to resolve either internal or external AD FS service name
- Windows Integrated authentication requires a DNS A record, not a CNAME record
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14. AD FS Requirements (2)
 Certificates
- Same SSL certificate for AD FS and Web Application proxies
- Common name of the certificate should match the service name
- User certificate authentication requires certauth.[federation service name] as SAN
- Device registration or modern authentication for pre-Windows 10 clients requires enterpriseregistration.[UPN suffix]
as SAN]
 Network
- Firewall policy to allow HTTPS on TCP 443
- Client user certificate authentication requires TCP 49443 to Web Application proxy, if certauth on 443 is not enabled
 Database
- Windows Internal Database
- SQL Server 2008 or higher
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15. AD FS Capacity Planning
 AD FS Capacity Planning Sizing Spreadsheet:
- Number of users requiring SSO access
- Number of users sending authentication requests (peak)
- Duration of peak usage period
- Geo redundancy information
- AD FS Proxy information
Link: AD FS 2016 Capacity Planning Spreadsheet
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16. High Availability for AD FS
 Why HA is essential
- Federated sources are not accessible when AD FS fails or is not reachable
 Load Balancing
- Use a simple Load Balancing solution
 Protecting SQL Server
- SQL Cluster
- SQL failover partner
 Office 365 Adapter for Windows Azure Virtual Machines
- White paper: Office 365 Adapter - Deploying Office 365 single sign-on using Azure Virtual Machines
https://technet.microsoft.com/en-us/library/dn509539.aspx
- Deployment scenarios for Office 365 with single sign-on and Azure
https://technet.microsoft.com/en-us/library/dn509537.aspx
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17. High Availability for AD FS – Azure for Disaster Recovery
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VPNTunnel
AD DS
1x
AAD
Connect
1x
AD FS
1x
AD FS
Proxy
2x
AD DS
AD FS
AAD
Connect
AD FS
AD FS
Proxy
AD FS
Proxy

18. High Availability for AD FS – Azure Only
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VPNTunnel
AD DS
1x
AAD
Connect
1x
AD FS
1x
AD FS
Proxy
2x
AD DS

19. Best Practices for AD FS
 Plan for AD FS proxy servers
 Avoid having federation servers directly accessible on the Internet
 Prepare DNS
- Split DNS requires proper DNS zone maintenance
 Networking, firewall, and security design
 Ensure certificates export includes private key
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20. Page  20
Questions
Thomas Stensitzki
Expert
Granikos GmbH & Co. KG
MCSM Messaging, MCM: Exchange 2010
MCT, MCSE, MCITP, MCTS, MCSA, MCSA:M
E-Mail: thomas.stensitzki@granikos.eu
Web: http://www.Granikos.eu
Blog: http://blog.Granikos.eu
Blog: http://JustCantGetEnough.Granikos.eu