implementing 802.1x authentication
DESCRIPTION
This is the presentation of my 802.1x Authentication seminar at New Horizons of Sofia, at 22.10.2008.TRANSCRIPT
802.1X Authentication802.1X Authentication
Deniz KayaMicrosoft, Cisco, Ironport TrainerCCSI, CCNP, MCT, MCSE, ICSI, ICSP, CPTS
…While the Assets Needing to be Protected are Expanding
Service Provider/Internet
Teleworker
City Hall
VPNHead-End
CableProvider
831
AirportLibrary
Partner/Vendor
One physical network, must accommodate multiple logical networks (user groups) each with own rules.
IDENTITY:So, you said MAC Address ?
Win 2K & XP allow easy change for MAC addresses
MAC address is not an authentication mechanism…
Determining “who” gets access and “what” they can do
User Identity BasedNetwork Access
User Based Policies Applied(BW, QoS etc)
Campus Network
• Equivalent to placing a Security Guard at each Switch Port
• Only Authorized users can get Network Access
• Unauthorized users can be placed into “Guest” VLANs
• Prevents unauthorized APs
AuthorizedUsers/Devices
UnauthorizedUsers/Devices
What Exactly Is 802.1x?
• Standard set by the IEEE 802.1 working group.
• Describes a standard link layer protocol used for transporting higher-level authentication protocols.
• Works between the Supplicant and the Authenticator.
• Maintains backend communication to an Authentication Server.
Some IEEE Terminology
IEEE Terms Normal People Terms
Supplicant Client
Authenticator Network Access Device
Authentication Server AAA/RADIUS Server
What Does it Do?
• Transport authentication information in the form of Extensible Authentication Protocol (EAP) payloads.
• The authenticator (switch) becomes the middleman for relaying EAP received in 802.1x packets to an authentication server by using RADIUS to carry the EAP information.
802.1x Header EAP Payload
What is RADIUS?
• RADIUS – The Remote Authentication Dial In User Service
• A protocol used to communicate between a network device and an authentication server or database.
• Allows the communication of login and authentication information. i.e.. Username/Password, OTP, etc.
• Allows the communication of arbitrary value pairs using “Vendor Specific Attributes” (VSAs).
RADIUS Header EAP PayloadUDP Header
802.1x – enhancing LAN securityTopology
DHCP Exchange
Filepeers
Controlle
d Port
Domain Controller
Certificate AuthoritySupplies client certs and
Certificate Revocation Lists (CRL)
EAP Connection
802.11/.1XAccess PointLaptop
Domain User/Machine
Certificate
ServerCertificate
RADIUS(IAS)
Uncontro
lled P
ort
Wired Access Control Model
Client and Switch Talk 802.1x Switch Speaks to Auth Server Using RADIUS
Actual Authentication Conversation Is between Client and Auth Server Using EAP;the Switch Is Just a Middleman, but Is Aware of What’s Going on
• RADIUS acts as the transport for EAP, from the authenticator (switch) to the authentication server (RADIUS server)
•RADIUS is also used to carry policy instructions back to the authenticator in the form of AV pairs.
Identity Based Network Services
Login Request
Login Info
Verify Login and Check with Policy DB
Login Good!Apply Policies
• Set port to enable• set port vlan 10
VLAN 10
Engineering VLAN
Switch applies policies and enables port.
Login + Certificate
Login Verified
AAA Radius Server
802.1x Authentication Server
Active Directory
Login and Certificate Services
6500 Series Access Points
4000 Series
3550/2950 Series
802.1x Capable Access Devices
802.1x Capable ClientIEEE802.1x+ VLANS+ VVID+ ACL+ QoS
802.1x client implementation in Windows
• Wired interfaces – enabled by default
• Wireless interfaces – integrated with the wireless configuration client– Enabled by default if privacy is enabled– Dynamic keys usage enforcement
• User and computer authentication enabled by default
802.1x in Microsoft WindowsMachine and user authentication
Startup
Machine
Machine credentials available(use machine credentials)
Machine authentication success Machine authentication failure
User logon
User credentials available(use user credentials)
User authentication success User authentication failure
User logoff
Windows Machine Authentication
Power Up
Load NDIS
drivers
DHCP Setup Secure Channel to DC
Update GPOs Apply Computer
GPOs
Present GINA (Ctrl-Alt-Del)
Login
802.1x Authenticate as Computer
• What is Machine Authentication?The ability of a Windows workstation to authenticate under it’s own identity, independent of the requirement for an interactive user session.
• What is it used for?Machine authentication is used at boot time by Windows OSes to authenticate and communicate with Windows Domain Controllers in order to pull down machine group policies.
• Why do we care?Pre-802.1x this worked under the assumption that network connectivity was a given. Post-802.1x the blocking of network access prior to 802.1x authentication breaks the machine based group policy model – UNLESS the machine can authenticate using its own identity in 802.1x .
802.1x in Microsoft Windows802.1x authentication configuration page
• Same for wired and wireless
• Provides control over computer and guest authentication
• EAP method setting
What is EAP?
• EAP – The Extensible Authentication Protocol
• A flexible protocol used to carry arbitrary authentication information.
EAP
TLSTLS GSS_APIGSS_APIKerberosKerberos
PEAPPEAPMS-CHAPv2MS-CHAPv2
TLSTLSIKEIKEMD5MD5
EAPEAP
PPPPPP 802.3802.3 802.5802.5 802.11802.11 Other…Other…
methodmethodlayerlayer
EAPEAPlayerlayer
mediamedialayerlayer
802.1x authentication clientEAP methods available in Windows
• EAP-TLS (Transport Level Security) – default setting for 802.1x client in Windows
• PEAP (Protected EAP) allows inner methods– TLS (certificate based)– Microsoft Challenge Handshake Authentication
Protocol v2 (MSCHAPv2) (password based)
• EAP-MD5 – available for wired networks only– Doesn’t provide encrypted session between
supplicant and authenticator– Transfers password hashes in clear
802.1x authentication clientEAP methods – wired and wireless networks
EAP with MD5
identity-request
AuthenticatorPeer
identity-response (username)
success or failure
MD5-challenge-request
MD5-challenge-response
cleartext password
R = MD5(password,challenge)
cleartext password
Check that MD5(password,challenge)equals the response
Random challenge
802.1x with EAP-TLSLocal store certificates
• Uses both user and computer certificates
• Certificates deployed through auto-enrollment, Web enrollment, certificate import, or manual request using the Certificates snap-in
• Local computer store is always available
• The user store (for a current user) is only available after a successful user logon
802.1x with EAP-TLSConfiguration page
• Mutual authentication enabled by default
• Simple certificate selection
802.1x with EAP-TLSSmart card certificates
• User must enter PIN to access the certificate on the smart card.– PIN input is not required again on subsequent re-
authentication tries – like session time-out or roaming on wireless networks.
– When roaming out of range and back in range, user will be re-prompted for PIN.
• Managing user certificates stored on local hard drives can be difficult, and some users may move among computers.
802.1x with PEAP-MSCHAPv2What to consider
• Password-based authentication – not all networks have a PKI deployment.
• Single sign-on (SSO).
• Enables both machine and user authentication.
• Windows logon credentials can be automatically used (default setting), or credentials can be provided by user.
802.1x with PEAP-MSCHAPv2Configuration page
• By default, fast reconnect feature is disabled.
Campus Identity - Supplicants
• Possible End-Points : Windows XP – YesWindows 2000 – Yes (SP3 + KB)Linux – YesHP-UX – YesSolaris - YesHP Printers – YesWindows 98 – LimitedWindows NT4 – LimitedApple – yesIP Phones – yesWLAN APs – yes….
Windows HP Jet Direct
Solaris 7920 Apple
IP Phones WLAN APsPocket PC
802.1xPort based network access control
• Falls under 802.1 NOT 802.11
• This is a NETWORK standard, not a wireless standard
• Is PART of the 802.11i draft
• Provides Network Authentication, NOT encryption
Know before you start !
• 802.1x Implementation requires various knowledge from different domains – Switch or AP Compliance and configuration– Certificate Services (Hidden part of the
ICEBERG) if you intend to you EAP-TLS– Radius Server, especially when you have a
multi-domain-directory infrastructure– Smart-card services, if you intend to use
them instead of user certificates– Various Client Deployment Scenarios
Demo – Wired Client Authentication 802.1x with PEAP-MSCHAPv2
• Cisco Switch Configuration
• Active Directory Configuration
• Installation of IAS (Radius)
• Installation of Certificate Services
• XP Client Configuration
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