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Outlook Web Access Publishing in ISA Server 2004: RSA SecurID and Forms-Based Authentication

Microsoft® Internet Security and Acceleration (ISA) Server 2004 Standard Edition and ISA Server 2004 Enterprise Edition work with Microsoft Outlook® Web Access to enhance security for Outlook Web Access servers. Outlook Web Access provides Web browser access to e-mail, scheduling (including group scheduling), contacts, and collaborative information stored in Microsoft Exchange store folders. Outlook Web Access is used by remote, home, and roving users.

When you publish Outlook Web Access servers through ISA Server, you are protecting the Outlook Web Access server from direct external access because the name and IP address of the Outlook Web Access server are not accessible to the user. The user accesses the ISA Server computer, which then forwards the request to the Outlook Web Access server according to the conditions of your mail server publishing rule.

Further, ISA Server enables you to easily configure forms-based authentication and to control e-mail attachment availability, to protect your corporate resources when accessed through Outlook Web Access. This document describes how to securely publish Outlook Web Access servers with mail server publishing rules using forms-based authentication to authenticate Outlook Web Access requests from external clients. In this scenario, ISA Server is not part of a domain, and it authenticates against an RSA ACE/Server®.

Forms-based authentication is a type of authentication in which an unauthenticated user is directed to a Hypertext Markup Language (HTML) form. After the user provides credentials, the system issues a cookie containing a ticket. On subsequent requests, the system first checks the cookie to see if the user was already authenticated, so that the user does not have to supply credentials again. Forms-based authentication is very useful in a scenario in which external client requests may be coming from untrusted computers.

  • When you use ISA Server 2004 with Exchange Server 2003, you must choose to use forms-based authentication of only one of the products. When using RSA SecurID® authentication and forms-based authentication, you must use forms-based authentication provided with the Exchange Server product.

Advantages of forms-based authentication include the following:

  • Credential information is not cached on the client computer. This is particularly important in a scenario where users are connecting to your Outlook Web Access server from public computers, where you would not want user credentials to be cached. Users are required to reauthenticate if they close the browser, log off from a session, or navigate to another Web site.
  • You can configure a maximum idle session time-out, so that if a user is idle for a prolonged period of time, the session expires and reauthentication is required.
  • Users cannot use the Remember my password option in Internet Explorer.

Note the following:

  • ISA Server supports forms-based authentication for Exchange Server 2003, Exchange 2000 Server, and Exchange Server version 5.5.
  • When you use Exchange Server 2003 forms-based authentication, ISA Server inspects request URLs, request headers, request bodies, and response headers, but does not inspect response bodies. However, you retain the Exchange data compression feature.
  • Outlook Web Access includes optional functionality that allows a user to change the password. If a user changes the password during an Outlook Web Access session, the cookie provided after the user initially logged on will no longer be valid.

Forms-Based Authentication in an NLB Scenario

For ISA Server 2004 Enterprise Edition, in a scenario involving multi-server ISA Server arrays, you must ensure that client requests for a particular session are handled by the same array member, so that the client’s cookie is recognized. If the request is received by a different member, the cookie will not be recognized and the request will be dropped by that ISA Server member. An effective way to ensure that the requests are handled by the same server member is to enable integrated Network Load Balancing (NLB) on the ISA Server array. The procedure for enabling integrated NLB is described in Appendix A: Configuring NLB on the ISA Server Array in this document.

One of the fundamental capabilities of ISA Server 2004 is the ability to apply a firewall policy to specific users. By default, ISA Server can authenticate users against local accounts on the ISA Server computer, communicate with the Active Directory® directory service servers (for Microsoft Windows® authentication) with RSA Authentication Managers (for RSA SecurID authentication) and with Remote Authentication Dial-In User Service (RADIUS) servers.

ISA Server 2004 introduces the ability to authenticate users, based on authentication credentials from the RSA SecurID product from RSA Security, Inc. ISA Server can secure Web sites requiring authentication credentials from RSA SecurID.

RSA SecurID enforces a requirement that a remote user must have two factors of authentication to gain access to protected resources. These two factors include something that a user knows, which is a personal identification number (PIN), and something that a user has, which is a physical token. Neither the PIN nor the token will grant access in isolation from each other. Both are required.

When a user attempts to access Web pages that are protected by RSA SecurID, the ISA Server computer, on behalf of the server running Internet Information Services (IIS) that it secures, checks for a cookie. This cookie will only be present if the user has authenticated recently, and it is not persistent. If the user's cookie is missing, the user is prompted for a user name and passcode for SecurID. This challenge is rendered appropriately to the browser type. If the user is using Internet Explorer, the challenge content type will be HTML. The passcode consists of a combination of the user's PIN and tokencode. The tokencode is displayed on the user's token and changes once every minute. The RSA ACE/Agent® on the ISA Server computer passes these credentials to the RSA ACE/Server computer for validation. If the credentials are successfully validated, a cookie is delivered to the user's browser for subsequent activity during the session, and the user is granted access to the content.

RSA SecurID is based on technology from RSA Security Inc. For additional information about RSA ACE/Server installation, configuration, and authentication concepts, see the documentation available at the RSA Web site.

The RSA SecurID protocol uses standard Hypertext Transfer Protocol (HTTP) messages to authenticate a client. The protocol is a variation of a request-based protocol, where the client sends special data attached to each request.

The following terminology is used:

  • RSA ACE/Server. This computer retains information about users, groups, hosts, and tokens. For each user, the RSA ACE/Server maintains a list of hosts to which the user can log on, and a logon name, which can differ from one host to the other.
  • RSA ACE/Agent. This computer provides Web content, and requires the user to provide credentials for RSA SecurID.
  • Client. Usually, this is a Web browser that receives Web content.

When a client sends a GET /x request to ISA Server, the following process occurs:

  • The Web filter for RSA SecurID Internet Server Application Programming Interface (ISAPI) authentication intercepts the request, and returns an RSA SecurID authentication form to the client.
  • The client is required to fill in the form with a logon name and a passcode.
  • The browser uses the HTTP POST method to return the form to the Web filter.
  • The Web filter for RSA SecurID authentication communicates these details to the RSA ACE/Server, to verify that the user is allowed access using the ISA Server computer. If the answer is positive, the Web filter returns a response that includes a Set-Cookie header to the client.
  • The Set-Cookie header writes a cookie to the browser's memory. When the browser is closed, the cookie is lost. The cookie contains information about the user. This information is signed with a secret known only to ISA Server. This means that the cookie cannot be modified by other users.
  • The response contains a Refresh header, which instructs the browser to resend the original GET /x request to the server.
  • When the Web filter receives a request with a cookie, it verifies that the cookie is valid, by checking:
    • Expiration time
    • IP address (if specified)
    • Signature (to ensure that the data was not tampered)
      If all checks pass successfully, the request is passed to any other installed Web filters on ISA Server, and then passed to ISA Server.
  • ISA Server tries to request the object, and the object is sent back to the client.

All incoming Outlook Web Access requests must be received by a Web listener. A Web listener may be used in multiple Outlook Web Access publishing and Web publishing rules.

When you configure a Web listener, you are specifying:

  • The network corresponding to the network adapter on the ISA Server computer that will listen for incoming Web requests. The Web listener can listen on all the IP addresses associated with a network or on specific IP addresses.
    Cc302537.note(en-us,TechNet.10).gifImportant:
    You may want to publish Outlook Web Access using NLB in your ISA Server 2004 Enterprise Edition array. We recommend that you enable NLB on the Outlook Web Access server network and on the External network. For the most effective use of NLB, your Web listener should listen on the NLB virtual IP address for the External network. If you configure your Web listener to listen on all of the IP addresses for the network adapters, it will listen on the virtual IP address, which will distribute requests using NLB, and on the dedicated IP addresses of the network adapters, which will not make use of NLB. The procedure for configuring NLB is described in Appendix A: Configuring NLB on the ISA Server Array in this document. The procedure for selecting the virtual IP address in a Web listener is described in Procedure 2: Create a Web Listener in this document.
  • The port number that will listen for incoming requests on the selected network IP addresses. For example, you can select to listen on port 80 for HTTP requests, on port 443 for HTTPS requests, or both. In the Outlook Web Access scenario, we recommend listening only for HTTPS requests, so that communication is secured by encryption.
  • Client authentication methods. After defining a Web listener, you will edit the Web listener properties to define the authentication method for requests. In this scenario, you will edit the Web listener to use RSA SecurID authentication.
    Cc302537.note(en-us,TechNet.10).gifNote:
    If ISA Server is configured with multiple network adapters, and you create a Web listener with RSA SecurID authentication enabled, you should explicitly configure the network adapter address through which ISA Server will connect to the RSA ACE/Server for authentication purposes. Otherwise, ISA Server may fail to perform SecurID authentication. Specify the IP address in registry key HKEY_LOCAL_MACHINE\SOFTWARE\SDTI\AceClient\PrimaryInterfaceIP as a string value. We recommend that you use Secure Sockets Layer (SSL) to encrypt the communication between the client and ISA Server.

Using ISA Server 2004, you want to publish an Outlook Web Access server so that users can access their e-mail messages from home computers and from Internet kiosks. You want the connection to the Outlook Web Access server to be secure, and you do not want credentials or proprietary information stored on the client computers. RSA SecurID authentication will be used to authenticate clients. Users

The prescribed solution is to publish the Outlook Web Access server through ISA Server 2004 using a mail server publishing rule. Communication from external clients to the ISA Server computer and from the ISA Server computer to the Outlook Web Access server will be encrypted using SSL. RSA SecurID authentication will be enabled on the Web listener that listens for Outlook Web Access requests. Forms-based authentication will be enabled on the Exchange server.

Publishing Outlook Web Access in ISA Server using forms-based authentication against an RSA ACE/Server consists of these general steps:

  • Set up RSA ACE/Agent on the ISA Server computer.
  • Set up the Outlook Web Access server.
  • Configure ISA Server.

The following computers are necessary to deploy this solution:

  • A computer to serve as the Outlook Web Access server on the Internal network. The Outlook Web Access server should run Microsoft Windows Server™ 2003 or Windows 2000 Server with Service Pack 3.
  • A computer to serve as the Exchange server on the Internal network. The Exchange server should run Exchange Server 2003.
  • An RSA ACE/Server on the Internal network.
  • In ISA Server 2004 Standard Edition:
  • A computer running ISA Server 2004 Standard Edition.
  • In ISA Server 2004 Enterprise Edition:
  • A computer to serve as the ISA Server Configuration Storage server.
  • A computer on the External network to test the solution.
    Cc302537.note(en-us,TechNet.10).gifNote:
    This walk-through assumes that you have installed ISA Server 2004 Standard Edition or ISA Server 2004 Enterprise Edition. In the case of Enterprise Edition, you should have installed a Configuration Storage server, and at least one ISA Server array, through which you are going to publish the Outlook Web Access server. Installation of these ISA Server components is described in the product documentation and in the Getting Started Guide at the Microsoft ISA Server Web site.
    When deploying ISA Server 2004 Enterprise Edition, you can use a single computer to host both the Configuration Storage server and ISA Server services. This configuration will not allow you to use NLB.
    When you enable SecurID authentication on a computer running Windows Server 2003, the Network Service account must have read/write access to the following registry key: HKLM\Software\SDTI\ACECLIENT. In addition, the Network Service account must have read permission for the Sdconf.rec file, located in %SystemRoot%\system32\.
  • A minimum of two computers running ISA Server services in an array.

The SecurID Web filter is enabled upon installation. For more information, see Enable or disable the Web filter for RSA SecurID authentication in ISA Server Help.

This walk-through contains the following series of procedures:

Configure the Outlook Web Access Server

Set up the ISA Server Computer

Configure ISA Server

Configure the Exchange Server

Test and Monitor the Deployment

Configure the Outlook Web Access Server

Perform the following procedures to configure the Outlook Web Access server:

  • Procedure 1: Configure a server certificate on the Outlook Web Access server
  • Procedure 2: Enable SSL on IIS

Procedure 1: Configure a Server Certificate on the Outlook Web Access Server

In this scenario, an SSL connection is preserved from the external client to the ISA Server computer, and from the ISA Server computer to the published Outlook Web Access server. A server certificate is required to authenticate ISA Server to external clients, which is usually a certificate from a certification authority (CA), and a server certificate is required on the Outlook Web Access server to authenticate it to the ISA Server computer. For instructions on configuring server certificates, see Digital Certificates for ISA Server 2004 at the Microsoft TechNet Web site.

Cc302537.note(en-us,TechNet.10).gifNote:
The recommended configuration for Outlook Web Access publishing is to use SSL-encrypted communication (HTTPS) both from the external client to the ISA Server computer and from the ISA Server computer to the Outlook Web Access server. ISA Server does not support Outlook Web Access publishing rules that forward HTTP requests from the external client to the Outlook Web Access server as HTTPS. If you create a publishing rule that forwards HTTPS requests from the external clients to the Outlook Web Access server as HTTP, do not enable link translation.

Procedure 2: Enable SSL on IIS

On the Outlook Web Access server, configure IIS for SSL communications only:

  1. Open the Internet Services Manager or your custom Microsoft Management Console (MMC) containing the IIS snap-in, expand the server node, expand the Default Web Site node, select virtual path /Exchange, and then click Properties.
  2. Click the Directory Security tab, and under Secure Communications, click Edit.
  3. In the Secure Communications dialog box, select the Require secure channel (SSL) check box, and then click OK twice.
  4. Repeat these steps for the virtual path /public.
  5. Repeat these steps for the virtual path /exchweb, but select Enable anonymous access and clear all other authenticated access check boxes.

Set Up the ISA Server Computer

Perform the following procedures to set up the ISA Server computer:

  • Procedure 1: Install a server certificate on ISA Server
  • Procedure 2: Add users to the ISA Server host record on the RSA ACE computer
  • Procedure 3: Set up the ISA Server computer as an RSA ACE/Agent
  • Procedure 4: Enable system policy
  • Procedure 5: Test connectivity between the ISA Server computer and the RSA ACE/Server

Procedure 1: Install a Server Certificate on ISA Server

In this scenario, an SSL connection is preserved from the external client to the ISA Server computer, and from the ISA Server computer to the published Outlook Web Access server. In such a scenario, a server certificate is required to authenticate ISA Server to external clients, which is usually a certificate from a certification authority (CA), and a server certificate is required on the Outlook Web Access server to authenticate it to ISA Server computer. For ISA Server 2004 Enterprise Edition, you will need to prepare and install an identical server certificate on each array member. For instructions on configuring server certificates, see Digital Certificates for ISA Server 2004 at the Microsoft TechNet Web site.

Procedure 2: Add Users to the ISA Server Host Record on the RSA ACE Computer

Users with valid authentication credentials must be specified on the RSA ACE/Server computer:

  1. On the RSA ACE/Server computer, click Start, click Programs, and then click Database Administration - Host Mode.
  2. On the Agent Host menu, click Add Agent Host.
  3. Add the ISA Server computer to the list of agents. If you are running ISA Server 2004 Enterprise Edition, repeat this step for each ISA Server computer in the array:
    1. In Name, type the name of the ISA Server computer.
    2. In Network address, type the IP address of the ISA Server computer, if it did not appear automatically.
    3. In Agent Type, select Communication Server.
  4. Generate the configuration file. To do this, on the Agent Host menu, click Generate Configuration File, click One Agent Host, click OK, double-click the name of the ISA Server computer, and save the Sdconf.rec file in a folder on the computer. If you are running ISA Server 2004 Enterprise Edition, repeat this step for each ISA Server computer in the array.
  5. Copy the Sdconf.rec file to the %windir%\system32 folder on the ISA Server computer.
Cc302537.note(en-us,TechNet.10).gifNote:
If you are running ISA Server 2004 Enterprise Edition, the Sdconf.rec file should have service network permissions.

Procedure 3: Set Up the ISA Server Computer as an RSA ACE/Agent

After you set up RSA ACE/Server on your network, and install the digital certificate, you must set up the ISA Server computer as an RSA ACE/Agent. After the RSA ACE/Agent is configured, you will need to test connectivity between the ISA Server computer and the RSA ACE/Server to verify that ISA Server can authenticate against the RSA ACE/Server.

To set up the ISA Server computer as an RSA ACE/Agent:

  • Copy the Sdconf.rec file, located in the ACE\Data folder on the RSA ACE/Server computer, to the %windir%\system32 folder on the ISA Server computer.

If you are using a version of RSA ACE/Server earlier than version 5.0, perform the following steps:

  1. On the RSA ACE/Server computer, click Start, click Programs, and then click Database Administration - Host Mode.
  2. On the Agent Host menu, click Add Agent Host.
  3. In Name, type the name of the ISA Server computer.
  4. In Network address, type the IP address of the ISA Server computer, if it did not appear.
  5. In Agent Host, click Generate Configuration File, click One Agent Host, click OK, double-click the name of the ISA Server computer, and save the Sdconf.rec file in a folder on the computer.
  6. Copy the Sdconf.rec file to the %windir%\system32 folder on the ISA Server computer.

Procedure 4: Enable System Policy

For the ISA Server computer to verify the authentication credentials for RSA SecurID, the system policy rule allowing communication with RSA SecurID must be enabled. The RSA ACE/Server must be specified in the system policy as the destination. To enable system policy, do the following:

  1. In the console tree of ISA Server Management, right-click the Firewall Policy node, as follows:
    • For Standard Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Server_Name, and then right-click Firewall Policy.
    • For Enterprise Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Arrays, expand Array_Name, and then right-click Firewall Policy.
  2. Click Edit System Policy.
  3. In the Authentication Services section of the Configuration Groups list, click RSA SecurID.
  4. On the General tab, select the Enable check box.
  5. Click the To tab, and then click Add.
  6. In the Add Network Entities page, on the New menu, click Computer.
  7. In the new Computer Rule Element page, specify the name and IP address for the RSA ACE/Server. Click OK. Select the new computer rule element from the list of computers, and then click Add. Click OK.
  8. In the Firewall Policy details pane, click Apply to update the configuration.
    When the System Policy Editor closes, you can view the system policy rule "Allow SecurID Authentication from ISA Server to Trusted Servers" properties in the Firewall Policy details pane.

Procedure 5: Test Connectivity Between the ISA Server Computer and the RSA ACE/Server

To verify that ISA Server 2004 can authenticate against the RSA ACE/Server, do the following:

  1. Copy Sdtest.exe from the \Tools folder CD or from the shared folder on your network that contains the ISA Server files to the ISA Install folder.
  2. Run Sdtest.exe.
  3. In RSA SecurID Authentication Information, click RSA ACE/Server Test Directly.
  4. In RSA SecurID Authentication, type the user name in Enter User Name and the passcode in Enter PASSCODE.
  5. Click OK when the Authentication successful message displays.

Configure ISA Server

Perform the following procedures to configure ISA Server:

  • Procedure 1: Back up your current configuration
  • Procedure 2: Create a Web listener
  • Procedure 3: Configure RSA SecurID authentication through the Web listener
  • Procedure 4: Create the mail server publishing rule to publish the Outlook Web Access server
  • Procedure 5: Create a cache rule

Procedure 1: Back Up Your Current Configuration

We recommend that you back up your ISA Server configuration before making any changes. If the changes you make result in behavior that you did not expect, you can revert to the previous backup configuration. To back up the complete configuration of your ISA Server computer to an .xml document, perform one of the following procedures.

For ISA Server 2004 Standard Edition, do the following:

  1. In the console tree of ISA Server Management, click the ISA Server computer name:
    • Expand Microsoft Internet Security and Acceleration Server 2004, and then click Server_Name.
  2. On the Tasks tab, click Backup this ISA Server Configuration.
  3. In Save in, specify the folder in which the export file will be saved.
  4. In File name, type a name for the exported file, and then click Backup.
  5. In Password and Confirm password, type a password that will be required to open and decrypt confidential information.

For ISA Server 2004 Enterprise Edition, do the following:

  1. Open Microsoft ISA Server Management.
  2. Click to expand Microsoft Internet Security and Acceleration Server 2004:
  3. For Enterprise Edition, expand Arrays, right-click the array through which you are going to publish Outlook Web Access, and then click Export (Back Up) to start the Export Wizard.
  4. On the Welcome page, click Next.
  5. On the Export Preferences page, you can select the following options:
    • You can choose to export confidential information. If you do, it will be encrypted during export. If you want to export confidential information, select Export confidential information and provide a password.
    • You can choose to export user permission settings, by selecting Export user permission settings. User permission settings contain the security roles of ISA Server users, for example, indicating who has administrative rights.
  6. Click Next.
  7. On the Export File Location page, provide the location and name of the file to which you want to save the configuration. Choose a meaningful name, and consider including the date in the name of the file. Click Next.
  8. On the Completing the Export Wizard page, click Finish.
  9. When the export has completed, click OK.
    Cc302537.note(en-us,TechNet.10).gifNote:
    Because the .xml document is being used as a backup, a copy of it should be saved on another computer in case of catastrophic failure.

Procedure 2: Create a Web Listener

Create a Web listener to listen for Outlook Web Access requests on the specified network. In this scenario, the specified network is the External network. The Web listener will listen for secure HTTPS requests only, and will use RSA SecurID authentication. To create a Web listener, do the following:

  1. In ISA Server Management, click the Firewall Policy node, as follows:
    • For Standard Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Server_Name, and then click Firewall Policy.
    • For Enterprise Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Arrays, expand Array_Name, and then click Firewall Policy.
  2. On the Toolbox tab, click Network Objects. On the toolbar beneath Network Objects, click New, and then click Web Listener.
  3. On the Welcome page of the New Web Listener Wizard, type the name of the new listener, such as Listener on External network for internal Web publishing, and then click Next.
  4. On the IP Addresses page, select the network that will listen for Web requests. Because you want ISA Server to receive requests from the External network (the Internet), the listener should be one or more IP addresses on the external network adapters of ISA Server. Therefore, select External. Do not click Next.
  5. Before you click Next on the IP Addresses page, select specific addresses on which the ISA Server computer will listen. Click the Address button. The default selection is to listen on all IP addresses on the network.
    For ISA Server 2004 Enterprise Edition, this will include both dedicated IP addresses and virtual IP addresses on the External network, where NLB is enabled. We recommend that you select The default IP address(es) for network adapters on this network. This will select the default virtual IP address if NLB is enabled, and will select the default IP addresses on the network adapters of the ISA Server array if NLB is not enabled. If you have enabled NLB, and have created more than one virtual IP address, you should select Specified IP addresses on the ISA Server computer in the selected network, and then select the specific virtual IP address in the Available IP Addresses list.
    Cc302537.ee681e09-9abd-44bb-8471-0577db064820(en-us,TechNet.10).gif
  6. Click OK, and on the IP Addresses page, click Next.
  7. On the Port Specification page, clear the Enable HTTP check box.
    Cc302537.1984e733-2a21-4710-87e2-cb2de02d78ea(en-us,TechNet.10).gif
  8. Select Enable SSL, and verify that the SSL port is set to 443 (default setting).
  9. Provide the certificate name in the Certificate field. To do this, click Select, select the certificate you installed, click OK, and then click Next. For information about certificates, see Digital Certificates for ISA Server 2004 at the Microsoft TechNet Web site.
    Cc302537.note(en-us,TechNet.10).gifImportant:
    For secure Outlook Web Access publication, we recommend that you listen only for SSL requests.
    Use only the standard port numbers, which are the default settings for Outlook Web Access publishing.
  10. On the Completing the New Web Listener Wizard page, review the settings, and click Finish.

Procedure 3: Configure RSA SecurID Authentication Through the Web Listener

After you create a new Web listener using the New Web Listener Wizard, use the following steps to configure the listener to use RSA SecurID:

  1. In ISA Server Management, click the Firewall Policy node, as follows:
    • For Standard Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Server_Name, and then click Firewall Policy.
    • For Enterprise Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Arrays, expand Array_Name, and then click Firewall Policy.
  2. On the Toolbox tab, click Network Objects. Expand Web Listeners. Double-click to open the properties for the Web listener you created in the previous procedure.
  3. On the Preferences tab, under Configure allowed authentication methods, click Authentication.
  4. In the list of authentication methods, clear any authentication method that is selected (the default is Integrated), and then select SecurID. This establishes RSA SecurID authentication for the Outlook Web Access Web listener, and for the mail server publishing rule that uses this listener.
    Cc302537.90d15c08-e0ad-4fb4-b1bb-cf8c80ad3f4e(en-us,TechNet.10).gif
  5. Select Require all users to authenticate, and then click OK.
  6. Click the RSA SecurID tab.
  7. Under Cookie expiration control, configure the maximum time that cookies can remain active before they expire.
    Cc302537.abfd823b-3c4d-4b34-a544-e305e7be1e98(en-us,TechNet.10).gif
  8. Because you are specifying dual-authentication methods (the user will use forms-based authentication to authenticate to the Outlook Web Access server), select the Send SecurID cookie to upstream server check box.
  9. Click OK to close the Web listener properties. In the Firewall Policy details pane, click Apply to apply the changes that you made.

Procedure 4: Create the Mail Server Publishing Rule to Publish the Outlook Web Access Server

To create a new mail server publishing rule using the New Mail Server Publishing Rule Wizard, follow these steps:

  1. Do one of the following:
    • For ISA Server 2004 Standard Edition, expand Microsoft ISA Server Management, expand Server_Name, and then click Firewall Policy.
    • For ISA Server 2004 Enterprise Edition, on one of the ISA Server array members, expand Microsoft ISA Server Management, expand Arrays, and expand the array that will publish Outlook Web Access. Click Firewall Policy.
  2. In the Firewall Policy task pane, on the Tasks tab, select Publish a Mail Server to start the New Mail Server Publishing Rule Wizard.
  3. On the Welcome page, provide a name for the rule, and then click Next.
  4. On the Select Access Type page, select Web client access: Outlook Web Access (OWA), Outlook Mobile Access, Exchange Server ActiveSync, and then click Next.
    Cc302537.1768e879-7afd-4b51-933a-af0c6bb78ffa(en-us,TechNet.10).gif
  5. On the Select Services page, select Outlook Web Access. You may also select Outlook Mobile Access and Exchange ActiveSync. Click Next.
    Cc302537.f80e82c2-f539-4b16-854d-e8a208520969(en-us,TechNet.10).gif
    Cc302537.note(en-us,TechNet.10).gifNote:
    Enable high bit characters used by non-English character sets is enabled by default. This allows double-byte character sets (DBCS) or Latin 1 characters, used in some non-English languages. If you clear this selection, requests using those characters will be blocked.
  6. On the Bridging Mode page, select which parts of the communication path will be secured by digital certificates and therefore take place using the HTTPS protocol. This can be the communication from the client to the ISA Server computer, the communication from the ISA Server computer to the Outlook Web Access server, both types of communications, or neither. We recommend that you select the default Secure connection to clients and mail server, so that both portions of the communications pathway are secured by digital certificates. This will require that a digital certificate be installed on the Outlook Web Access server and on the ISA Server computer, as described in the document Digital Certificates for ISA Server 2004 at the Microsoft TechNet Web site. Click Next.
    Cc302537.b93937c6-5181-4af3-9db1-96d12bdd979e(en-us,TechNet.10).gif
  7. On the Specify the Web Mail Server page, enter the name or IP address of the Outlook Web Access server. This name must match the name on the Outlook Web Access server digital certificate. Click Next.
  8. On the Public Name Details page, provide information regarding what requests will be received by the ISA Server computer and forwarded to the Outlook Web Access server. In Accepts requests for, if you select Any domain name, any request that is resolved to the IP address of the external Web listener of the ISA Server computer will be forwarded to your Outlook Web Access server. If you select This domain name and provide a specific domain name, such as mail.fabrikam.com, assuming that domain is resolved to the IP address of the external Web listener of the ISA Server computer, only requests for https://mail.fabrikam.com will be forwarded to the Outlook Web Access server. Click Next.
    Cc302537.note(en-us,TechNet.10).gifNote:
    For ISA Server 2004 Enterprise Edition, the public name must match the name of the digital certificate on the ISA Server array.
  9. On the Select Web Listener page, specify the Web listener that you created previously, and then click Next.
  10. On the User Sets page, the default, All Users, is displayed. This will allow any authenticated user in the External network to access the Outlook Web Access server. To restrict the access to specific users, use the Remove button to remove All Users, and the Add button to access the Add Users dialog box, from which you can add the user set to which the rule applies. The Add Users dialog box also provides access to the New User Sets Wizard through the New menu item. When you have completed the user set selection, click Next.
  11. On the Completing the New Mail Server Publishing Rule Wizard page, scroll through the rule configuration to make sure that you have configured the rule correctly, and then click Finish.
  12. In the ISA Server details pane, click Apply to apply the changes you have made. It will take a few moments for the changes to be applied.

Procedure 5: Create a Cache Rule

To take advantage of the ISA Server caching feature, you can create a cache rule to enable caching of the images served by Outlook Web Access. When the ISA Server caching feature is enabled, all Outlook Web Access objects will be cached. This can lead to unexpected logging off of users. To avoid this, you must create a cache rule to prevent the caching of Outlook Web Access objects except for images. The cache rule must have the following properties:

  • Cache Rule Destination. Specify a URL set containing http://NameOfOutlookWebAccessServer//exchweb/*. After you create the rule using the New Cache Rule Wizard, open the rule properties, and on the To tab, add http://NameOfOutlookWebAccessServer//exchweb/img/* to the Exceptions. This will allow caching of the img (images) path.
  • Content Retrieval. Select the option Only if a valid version of the object exists in the cache.
  • Cache Content. Select the option Never, no content will ever be cached.

Create a cache rule as follows:

  1. In the console tree of ISA Server Management, click Cache:
    • For Enterprise Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Arrays, expand Array_Name, expand Configuration, and then click Cache.
    • For Standard Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Server_Name, expand Configuration, and then click Cache.
  2. In the details pane, click the Cache Rules tab.
  3. In the task pane, on the Tasks tab, select Create a Cache Rule to start the New Cache Rule Wizard.
  4. On the Welcome page of the wizard, provide a name for the rule, and then click Next.
  5. On the Cache Rule Destination page, click Add to open the Add Network Entities dialog box, select the appropriate network entity, click Add, and then click Close. On the Cache Rule Destination page, click Next.
  6. On the Content Retrieval page, leave the default selection Only if a valid version of the object exists in the cache, and then click Next.
  7. On the Cache Content page, select options as described earlier in this procedure.
  8. You can use the default selections on the remaining wizard pages. Information about cache rule properties is provided in the product Help. Review the information on the wizard summary page, and then click Finish.

Configure the Exchange Server

Perform the following procedures to configure the Exchange server:

  • Procedure 1: Enable forms-based authentication
  • Procedure 2: Require the saving of attachments in Exchange

Procedure 1: Enable Forms-Based Authentication

To configure the Exchange server to use forms-based client authentication, do the following:

  1. On the Exchange server, click Start, point to Programs, click Internet Authentication Service, and then click System Manager.
  2. Select the relevant server, click Protocols, click HTTP, right-click Exchange virtual server, and then select Properties.
  3. On the Settings tab, click Enable Forms Based Authentication, and then click OK.
  4. Close System Manager.

Procedure 2: Require the Saving of Attachments in Exchange

You can completely block attachments received through Outlook Web Access, so that the user cannot open or save any attachments.

If you do not block attachments, note that some attachments, such as Windows Media® files and Microsoft Excel spreadsheets, cannot be opened directly by a client connected remotely to an Outlook Web Access server. An attempt to open such a file will result in a failure of the application associated with the file. Those files must be saved locally and can then be opened. You can avoid this problem by configuring Exchange Server 2003 and Exchange 2000 Server to force users to save attachments. This feature is not available in Exchange Server 5.5.

To force users to save attachments, configure the following registry key on the Exchange Server computer:

HKLM\SYSTEM\CurrentControlSet\Services\MSExchangeWEB\OWA\Level2FileTypes

This registry value specifies a set of file extensions that are potentially dangerous as attachments. Attachments matching these types will not be opened automatically. Instead, users will be prompted to save the attachments locally on their computers.

Cc302537.note(en-us,TechNet.10).gifNote:
You cannot configure Exchange Server 5.5 to require the saving of attachments.

Test and Monitor the Deployment

Perform the following procedures to test and monitor the deployment:

  • Procedure 1: Test Outlook Web Access
  • Procedure 2: Test Outlook Mobile Access
  • Procedure 3: Test Exchange ActiveSync
  • Procedure 4: View Outlook Web Access session information in ISA Server logs
  • Procedure 5: Monitor RSA ACE/Server

Procedure 1: Test Outlook Web Access

An external client can access the Outlook Web Access server provided that it can resolve a fully qualified domain name to the external IP address of the ISA Server computer. This would usually be achieved by registering a public Internet domain name with a public Domain Name System (DNS) server that maps the Web site name to the external IP address of ISA Server. To test the deployment in a lab environment, you can specify the Web site host name resolution information using Microsoft Notepad, in the client Hosts file located in \system32\drivers\etc\hosts in the Windows installation directory.

To connect to the Outlook Web Access site from the external client, type the Web address, such as https://mail.fabrikam.com/exchange. Be certain to specify https in the URL, as shown.

When you connect, you should see a logon page requesting credentials and the session type (public or private). You must provide this information before you can access your mailbox.

If you have set time-outs or blocked attachments, you can test those features by leaving the browser inactive for a period of time and then trying to access mail, and by trying to open or save attachments.

Procedure 2: Test Outlook Mobile Access

From a computer with Internet access, use Internet Explorer to connect to your Outlook Mobile Access DNS address and make sure that Outlook Mobile Access is working properly.

Cc302537.note(en-us,TechNet.10).gifNote:
Although Internet Explorer is not a supported client for Outlook Mobile Access, it is useful to test whether you can communicate with your Exchange front-end server.

After you successfully connect to your Exchange server using Outlook Mobile Access, verify that you can connect to your Exchange server using a supported mobile device with Internet connectivity.

Procedure 3: Test Exchange ActiveSync

Configure a mobile device to connect to your Exchange server using Microsoft Exchange ActiveSync®, and make sure that ISA Server and Exchange ActiveSync are working properly.

Cc302537.note(en-us,TechNet.10).gifNote:
You can also test Exchange ActiveSync using Internet Explorer. Open Internet Explorer, and in Address, type the URL https://published_server_name/Microsoft-Server-Activesync, where published_server_name is the published name of the Outlook Web Access server (the name a user would use to access Outlook Web Access). After you authenticate yourself, if you receive an Error 501/505 – Not implemented or not supported, ISA Server and Exchange ActiveSync are working together properly.

Procedure 4: View Outlook Web Access Session Information in ISA Server Logs

ISA Server will log the requests that match the mail server publishing rule, if Log requests matching this rule is selected on the Action tab of the rule properties. (This is the default condition.)

To check the logging property of the rule, follow these steps:

  1. Do one of the following:
    • For ISA Server 2004 Standard Edition, expand Server_Name, and then click Firewall Policy.
    • For ISA Server 2004 Enterprise Edition, in the Microsoft ISA Server Management console tree, under Arrays, expand the array that publishes Outlook Web Access, and then click Firewall Policy.
  2. In the details pane, double-click the mail server publishing rule to open its properties dialog box.
  3. Select the Action tab and confirm that Log requests matching this rule is selected.
    Cc302537.6b0b997d-d89a-4012-88fc-407a95be1ea6(en-us,TechNet.10).gif
  4. Click OK to close the properties dialog box.

To view the information in the log, follow these steps:

  1. In the Microsoft ISA Server Management console tree, select Monitoring.
  2. In the Monitoring details pane, select Logging.
  3. Create a filter so that you receive only the log information regarding Outlook Web Access access attempts. In the task pane, on the Tasks tab, click Edit Filter to open the Edit Filter dialog box. The filter has three default conditions, specifying that the log time is live, that log information from both the firewall and the Web Proxy should be provided, and that connection status should not be provided. You can edit these conditions, and add additional conditions to limit the information retrieved during the query.
  4. Select Log Time. From the Condition drop-down menu, select Last 24 Hours, and then click Update.
  5. You can add another expression by selecting an item from the Filter by drop-down menu, and then providing a Condition and Value. For example, to limit the log to display access to your published Web servers, you can have these expressions: Filter by: Log Record Type, Condition: Equals, Value: Web Proxy Filter, and Filter by: Service, Condition: Equals, Value: Reverse Proxy. This will limit the log to items that match Web publishing rules, including the Outlook Web Access publishing rule.
  6. After you have created an expression, click Add To List to add it to the query list, and then click Start Query to start the query. The Start Query command is also available in the task pane on the Tasks tab.

Procedure 5: Monitor RSA ACE/Server

To monitor the RSA ACE/Server, follow these steps:

  1. Do one of the following:
    • For Enterprise Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Arrays, expand Array_Name, and then click Monitoring.
    • For Standard Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Server_Name, and then click Monitoring.
  2. In the details pane, click the Connectivity tab.
  3. In the task pane, on the Tasks tab, click Create New Connectivity Verifier.
  4. On the Welcome page of the wizard, type a name for the connectivity verifier, and then click Next.
  5. On the Connectivity Verification Details page, do the following:
  6. In Monitor connectivity to this server or URL, type the name of the RSA ACE/Server.
  7. In Verification method, select Send a Ping request, and then click Next.
  8. Click Finish.
  9. In the details pane, select the rule you just created.
  10. On the Tasks tab, click Edit Selected Verifier.
  11. On the Properties tab, verify that Trigger an alert if the server response is not within the specified timeout is selected.

The following provides information on how to configure Network Load Balancing (NLB) on the ISA Server 2004 Enterprise Edition array.

You can use the NLB functionality of ISA Server 2004 Enterprise Edition to configure and manage the NLB functionality of Microsoft Windows Server 2003 running on ISA Server arrays. NLB configuration is performed through ISA Server Management.

When you configure NLB through ISA Server, NLB is integrated with ISA Server functionality. This provides important functionality that is not available in Windows NLB alone:

  • ISA Server works with Windows NLB to automatically configure bidirectional affinity, and does so for multiple networks. This guarantees that traffic is handled in both directions by the same array server. This is particularly important in Outlook Web Access, because it ensures that the client communicates with the same ISA Server array member for a particular session, so that the client’s cookie is recognized by ISA Server.
  • ISA Server provides NLB health monitoring, and discontinues NLB on a particular computer as necessitated by its status. This prevents the continued functioning of NLB when the state of the computer does not allow the passage of traffic. For example, if there is a failure of the network adapter on the computer, or if you stop the Microsoft Firewall service, ISA Server stops NLB-directed traffic from passing though that computer. When the issue is resolved, ISA Server will again allow NLB traffic to pass through that computer.

The following procedure describes how to configure NLB for an array. NLB will be automatically configured in unicast mode and single affinity. Single affinity ensures that all network traffic from a particular client be directed to the same host. This procedure takes place on a computer in an ISA Server array. You must be logged on as an array or enterprise administrator.

To configure NLB for an array, do the following:

  1. On one of the ISA Server array members, expand Arrays, expand the array node, expand Configuration, and click Networks.
  2. In the details pane, verify that the Networks tab is selected.
  3. In the task pane, on the Tasks tab, click Enable Network Load Balancing Integration to start the Network Load Balancing Integration Wizard. On the Welcome page, click Next.
  4. On the Select Load Balanced Networks page, select the networks for which NLB will be enabled. We recommend that you enable NLB on the Outlook Web Access server network, and on the External network. Select those networks. Do not click Next.
  5. Before you click Next, you must set the virtual IP address for each network. To set the virtual IP address, after you select the network, click Set Virtual IP. In the Set Virtual IP Address dialog box, provide the IP address and subnet mask for the virtual IP address you will use. Note that this IP address must be a valid static IP address that cannot be assigned by your Dynamic Host Configuration Protocol (DHCP) server, and must belong to the network you are configuring. Click Next.
  6. On the summary page, click Finish.
  7. In the details pane, click Apply.

Additional ISA Server 2004 documents are available at ISA Server 2004 Guidance.

References

For information about how to deploy Outlook Web Access in Exchange Server 2003, see the Exchange Server 2003 Deployment Guide at the Microsoft Download Center.

For information about how to deploy Outlook Web Access in Exchange 2000 Server, see Outlook Web Access in Exchange 2000 Server at the Microsoft Download Center and Customizing Microsoft Outlook Web Access at the Microsoft Download Center.

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