Using SAML for Single-Sign-On to the CenturyLink Platform Control Portal

Updated by Richard Seroter on Mar 5, 2015

Description

CenturyLink Cloud supports the use of Security Assertion Markup Language (SAML) for exchanging user authentication data as XML between trusted parties. This industry standard protocol empowers our customers to use their own identity management system for authenticating users of the CenturyLink Cloud Control Portal.

SAML has three main parties: the user, the identity provider (IdP), and service provider (SP). The IdP is the repository that holds identity information. The SP is the party that wants to authenticate a particular user who is using an application.

The SAML flow occurs as shown below. SAML Flow

Specific steps in this flow are:

  1. The enterprise user of the CenturyLink Cloud hits a URL that is dedicated to their account. The user is asked how they would like to log into the system and they choose SAML.

  2. The web application contacts the CenturyLink Cloud SAML service to initiate the SAML message exchange.

  3. The CenturyLink Cloud SP sends a digitally signed SAML authentication request to the enterprise IdP. This IdP takes the user's Kerberos token and validates them as a user on the enterprise network.

  4. The IdP returns a signed (and optionally, encrypted) SAML authentication response message to the CenturyLink Cloud SP. This message includes a Name ID assertion and that value is matched to a User record in the CenturyLink Cloud.

  5. The user is logged into the CenturyLink Cloud and operates under the roles and permissions assigned to their CenturyLink Cloud user account.

The steps below walk through the process of building an entire SSO and SAML scenario based on Microsoft Active Directory Federation Services as the IdP proxy. If you already have an identity provider, you can skip to step 3 where trust is established between CenturyLink Cloud and the IdP.

Steps

1. Provision server to act as Identity Provider.

  • Log into the CenturyLink Cloud Control Portal and choose to create a new Blueprint. Using the left navigation bar, choose Orchestration > Design Blueprint.

  • Include a single (Windows Server 2008 or above) server to the Blueprint and add packages to Install DNS, Install Active Directory, Reboot, Install IIS, and Add a Public IP. The DNS and Active Directory packages give us a custom domain to work with, and an identity directory for our user records. Microsoft Internet Information Services (IIS) provides a web application host for the Active Directory Federation Services (ADFS) web services used later on. Finally, the public IP address exposes our server to the public internet where applications (like the CenturyLink Cloud Control Portal) can access it for a SAML exchange.

Blueprint Designer

  • Publish the Blueprint and then locate it in the Blueprint library. Click the Deploy Blueprint button to initiate the provisioning process.

Deploy Blueprint

  • On the "Customize Blueprint" step of the deployment wizard, the user is asked to provide deploy-time build parameters such as the server password, host network, and Active Directory domain name. Note a few key values: first, the Primary DNS value must be equal to the name of the server being created. Recall that we already added DNS services to the server itself, so THIS is the domain that the new server should use for resolution. The Domain Name parameter typically contains the full name of the domain (including a suffix such as ".com") while the Net BIOS Name omits the suffix.

Server Build

  • Complete the deployment process and wait for the new server to be built by the CenturyLink Cloud Blueprint engine.

Blueprint Queue

  • Locate the server in the designated group and confirm its DNS value and public IP address.

Confirm Server Details

2. Install and configure Active Directory Federation Services.

  • Open client VPN software and connect to the CenturyLink Cloud network. Once authenticated, create a Remote Desktop session to the target server. In the Server Manager, confirm the installation of DNS, Active Directory, and IIS.

Server Manager

  • In order to issue certificates easily from this server, install the Certificate Services role on the server. Choose the Certificate Authority role, select Enterprise CA, set this to a Root CA, and create a new private key. Finish the wizard.

Certificate Services

  • Open the IIS Manager, click the host name, and locate the Server Certificates feature.

Server Certificates

  • Double-click the Server Certificates icon and select the option on the right to Create Domain Certificate. On the first page of the wizard choose the common name (it could be a wildcard entry like tier3samldemo.com) and organizational details.

Create Certificate

  • On the next page of the wizard, choose the Certificate Authority and set the friendly name of the certificate.

Friendly Name

  • After completing the wizard (and creating a certificate that should show up in the Certificates MMC as a Personal certificate for the Computer account), right-click the Default Web Site in the IIS Manager and choose Edit Bindings. Here, we set the site to use our new certificate for SSL.

Add Site Binding

  • For users working with Windows Server 2008 or Windows Server 2008 R2, download ADFS 2.0 download from the Microsoft website. Windows Server 2012 comes with ADFS pre-installed. Run the ADFS Setup Wizard.

Setup Wizard

  • Select the Federation server role, and complete the short wizard. Once the wizard installs prerequisite software and finishes installing ADFS 2.0, choose the option to launch the ADFS Configuration Wizard.

Configuration Wizard

  • Choose to Create a new Federation Service, a Stand-alone federation server, and notice that the wizard pulls in the name of the certificate set for SSL in IIS.

Create New

  • When the wizard completes, notice the new ADFS configuration options.

New Options

  • Before proceeding, add a new user to the Active Directory. In the Server Manager, expand the Active Directory Domain Services node, then Active Directory Users and Computers, and then the domain.

Menu Expand

  • Right-click on the Users node and select New, then User. Add the details of this new user and save the settings.

New User

3. Create trust relationship with CenturyLink Cloud.

  • Prior to starting this step, contact the CenturyLink Cloud NOC to acquire the public certificate that validates the message coming from CenturyLink Cloud.
  • In the ADFS 2.0 Management console (or whatever IdP service that's being used), create a new Relying Party Trust. This is where the settings from the CenturyLink Cloud are added to the local IdP so that it recognizes the SAML authentication request and can validate the inbound signature.

Add Party Trust

  • Choose the option to add the relying party metadata manually.

Enter Data Manually

  • Name the relying party something like "CenturyLink Cloud Control Portal." Select the ADFS 2.0 profile. When asked for the Relying party trust identifier, use the following value (while filling in your specific account alias): https://alias.cloudportal.io/SAMLAuth. Note that this value is case-sensitive!

Configure Identifiers

  • Finish the wizard, and plan on addition a pair of additional values later on. On the last wizard page, click the checkbox to Open the Edit Claims Rules dialog. Here is where we define which Active Directory values (claims) map to the SAML attributes sent back to CenturyLink Cloud.

Select Rule Template

  • Set the source of attributes (Active Directory), choose the User-Principal-Name as the LDAP Attribute, set the Outgoing Claim Type to Name ID.

Configure Claim Rule

  • After completing this wizard, go back to the Relying Party Trusts folder and open the new entry. Switch to the Signatures tab, and add the certificate provided to you by the CenturyLink Cloud NOC.

Properties

Add Endpoint

  • Finally, on the Advanced tab, change the Secure Hash Algorithm to SHA-1. Save the Relying Party Trust entry.

4. Configure CenturyLink Cloud account with SAML settings.

  • Log into the CenturyLink Cloud Control Portal and under Account menu, select the Users tab.

Users

  • Switch to the Authentication sub-section and check the box labeled SAML Authentication. This opens up a series of configuration settings.

SAML Config

  • For the SAML SSO URL,set the ADFS service URL. This includes the domain name the ADFS server. Even if you don't own the public domain name used here, enter the domain created for the local server.

SAML SSO URL

  • To get the Signing Certificate Key, return to the ADFS server, view the ADFS Management Console, and find the Certificates directory under the Services node. Notice the Token-signing certificate.

Token Signing

  • Choose to view the certificate (by right-clicking it), switch to the Details tab and select Copy to File. Export a Base-64 encoded X.509 certificate.

Export

  • Save the file to a known location on the file system. Open the file with a text editor and copy all of the text between the "Begin Certificate" and "End Certificate" indicators.

Cert

  • Paste this value into the Signing Certificate Key field in the CenturyLink Cloud Control Portal. Click the Save button and switch back to the Users List view. Select the user that you want to perform SSO with, and locate the SAML Username field. Since we chose above to use the Active Directory User Principal Name as the lookup value to the CenturyLink Cloud account, we must plug in the User Principal Name associated with this user.

SAML User

  • Save the user record.

5. Exchange SAML messages to perform Single Sign On.

  • Before testing, if you do not own the public domain name corresponding to the DNS name of your server, then your test will fail. To test successfully, change your local machine host file so that the browser translates the domain name to the public IP address of the server. When the SAML request comes in to ADFS, it tries to match the SAML Destination ID (retrieved from the SAML configuration in your CenturyLink Cloud account) to the Federation Service name in the ADFS server.

FS Properties

  • If the values do not match, then ADFS will return an exception. In order to test this scenario without registering and owning the corresponding public domain name, navigate to your local machine's host file (C:\Windows\System32\Drivers\etc\hosts) and add an entry that maps the public IP address of the server to the DNS name of the server.

hosts.txt

  • Go to a web browser and plug in https://alias.cloudportal.io. Here you can sign in via CenturyLink Cloud username and password, or choose the Sign In Using SAML option. If you choose the latter, then the CenturyLink Cloud SAML service redirects the browser to the URL specified in the account's SAML SSO URL setting.

Sign In Page

  • Clicking the Sign In Using SAML results in the following message being sent to the ADFS (or any IdP) service.
<samlp:AuthnRequest
  ID="--ID--"
  Version="2.0"
  IssueInstant="2012-12-06T21:30:41.385Z"
  Destination="https://tier3samldemo.com/adfs/ls/"
  ForceAuthn="false"
  IsPassive="false"
  ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST"
  AssertionConsumerServiceURL="https://ALIAS.cloudportal.io/SAMLAuth/Post"
  xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol">
  <saml:Issuer xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">https://ALIAS.cloudportal.io/SAMLAuth</saml:Issuer>
  <Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
    <SignedInfo>
    <CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#" />
    <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1" />
      <Reference URI="URI">
       <Transforms>
          <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature" />
          <Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#">
      <InclusiveNamespaces PrefixList="#default samlp saml ds xs xsi" xmlns="http://www.w3.org/2001/10/xml-exc-14n#"/>
          </Transform>
        </Transforms>
        <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" />
        <DigestValue>VALUE</DigestValue>
      </Reference>
    </SignedInfo>
    <SignatureValue>VALUE</SignatureValue>
  <KeyInfo>
     <X509Data>
       <X509Certificate>CERTIFICATE</X509Certificate>
     </X509Data>
        </KeyInfo>
        </Signature>
  <samlp:NameIDPolicy AllowCreate="true" />
</samlp:AuthnRequest>
  • If the SAML request is successfully processed by the ADFS server, then ADFS sends a SAML response that the CenturyLink Cloud Control Portal uses to log in the federated user.
<samlp:Response ID="--ID--"
  Version="2.0"
  IssueInstant="2012-12-06T22:22:35.344Z"
  Destination="https://ALIAS.cloudportal.io/SAMLAuth/Post"
  Consent="urn:oasis:names:tc:SAML:2.0:consent:unspecified"
  InResponseTo="ID" xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol">
  <Issuer xmlns="urn:oasis:names:tc:SAML:2.0:assertion">http://tier3samldemo.com/adfs/services/trust</Issuer>
  <samlp:Status>
    <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success" />
  </samlp:Status>
  <Assertion ID="ID" IssueInstant="2012-12-06T22:22:35.303Z" Version="2.0" xmlns="urn:oasis:names:tc:SAML:2.0:assertion">
  <Issuer>http://tier3samldemo.com/adfs/services/trust</Issuer>
     <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
       <ds:SignedInfo>
    <ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#" />
    <ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1" />
    <ds:Reference URI="URI">
       <ds:Transforms>
         <ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature" />
         <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#" />
       </ds:Transforms>
       <ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
       <ds:DigestValue>VALUE</ds:DigestValue>
    </ds:Reference>
    </ds:SignedInfo>
      <ds:SignatureValue>VALUE</ds:SignatureValue>
      <KeyInfo mlns="http://www.w3.org/2000/09/xmldsig#">
        <ds:X509Data>
          <ds:X509Certificate>CERTIFICATE</ds:X509Certificate>
        </ds:X509Data>
      </KeyInfo>
      </ds:Signature>
      <Subject>
    <NameID>[email protected]</NameID>
     <SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">
    <SubjectConfirmation Data InResponseTo="ID"
      NotOnOrAfter="2012-12-06T22:27:35.346Z"
      Recipient="https://ALIAS.cloudportal.io/SAMLAuth/Post" />
    </SubjectConfirmation>
       </Subject>
       <Conditions NotBefore="2012-12-06T22:22:34.417Z" NotOnOrAfter="2012-1206T23:22:34.417Z">
    <AudienceRestriction>
      <Audience>https://ALIAS.cloudportal.io/SAMLAuth</Audience>
    </AudienceRestriction>
       </Conditions>
       <AuthnStatement AuthnInstant="2012-12-06T22:22:33.401Z" SessionIndex="ID">
    <AuthnContext>
      <AuthnContextClassRef>urn:federation:authentication:windows</AuthnContextClassRef>
    </AuthnContext>
       </AuthnStatement>
    </Assertion>
</samlp:Response>
  • The user experience when clicking that button is that the user is prompted for credentials (if the user is not hitting the website from within the domain itself) and once provided, the user is automatically logged into the CenturyLink Cloud portal. Because they used Single Sign On and SAML, they did NOT have to enter their CenturyLink Cloud account credentials, but rather, were able to use their regular network credentials.

Updated Signing Certificate (March 2015)

Customers with an existing SAML configuration as of March 5 2015 will need to update their signing certificate for use with their IdP with the following text:

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

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