Configuring a gateway to gateway VPN is easy using ISA Server

Configuring a gateway to gateway VPN is easy using ISA Server. The reason why it’s so easy is that the Local and Remote VPN Wizards make the setup a virtual no-brainer. Well, it’s a no-brainer when you’re configuring PPTP VPN gateways. But if you’re in the market for a high security L2TP/IPSec gateway to gateway VPN, you probably have either been trying to avoid it like the plague or you are pulling your hair out trying to figure out how to make it work! Indeed, the certificate infrastructure configuration is a major barrier to entry for those considering L2TP/IPSec VPNs. The reason for this is that’s its virtually impossible to get the straight dope on how to install the certificates! Even the highly acclaimed VPN book by Fortenberry fails to make it clear how to install machine certificates using the Web interface for machines that are not domain members. He focuses on using the Web interface to get a user certificate for PPP EAP/TLS authentication. Forget about this! We’ll handle EAP/TLS at another time. What we want to do right now is to get a L2TP/IPSec link configured and working. Attention: Configuring ISA Server 2000 : Building Firewalls for Windows 2000 By Deb and Tom Shinder http://www.amazon.com/exec/obidos/ASIN/1928994296/isaserver http://www.a mazon.com/exec/obidos/ASIN/1928994296/isaserver Amazon.com The real trick in making the certificate services infrastructure work is the ability to assign certificates to non-domain member computers. As you’ll see, assigning certificates to domain members is a snap. Its getting the non-domain members a certificate that can give you a headache. In this lab we’ll put together a five computer VMware network that includes two VPN servers, a domain controller, a stand-alone root CA and a server on the remote network. In the first part of the article, we’ll get the infrastructure put together; install the servers, configure the certificate servers, and install certificates on the Local network. In the second part of the article we’ll install ISA Server, configure the gateway to gateway VPN, and install the certificates on the remote VPN server and remote file server. Procedures in this lab include: Reviewing the Lab Network Installing Certificate Server on a Domain Controller Configuring autoenrollment using Group Policy Confirming Installation of the Machine Certificate Using the MMC Console to Request a Certificate Installing a Stand-alone Root CA Obtaining a Certificate from the Stand-alone Root using the Web Interface By the end of this two part lab, you’ll be the ISA/VPN L2TP/IPSec gateway to gateway Wizard! The Lab Network The graphic below shows the lab network: Service and IP configuration settings on each machine: CLIENTDC: Services: WINS DNS --Accepts dynamic updates --Configured manually, not via Active Directory Wizard Active Directory Domain name: internal.net [IMAGE PROVIDED with LAB on DVD] IP Configuration: Windows 2000 IP Configuration Host Name . . . . . . . . . . . . : CLIENTDC Primary DNS Suffix . . . . . . . : internal.net DNS Suffix Search List. . . . . . : internal.net Ethernet adapter Local Area Connection: IP Address. . . . . . . . . . . . : 10.0.0.2 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 10.0.0.1 DNS Servers . . . . . . . . . . . : 10.0.0.2 Primary WINS Server . . . . . . . : 10.0.0.2 Installation Notes: Install Windows 2000 Advanced Server into the VM. Use the default settings except add the WINS and DNS server services and configure the IP settings manually. Create the DNS zone, internal.net before running DCPROMO. Make sure you create both forward and reverse lookup zones (reverse lookup zone for network ID 10.0.0./24). CERTSRV: Services: No additional network services on installation IP Configuration: Windows 2000 IP Configuration Host Name . . . . . . . . . . . . : CERTSRV Primary DNS Suffix . . . . . . . : internal.net DNS Suffix Search List. . . . . . : internal.net Ethernet adapter Local Area Connection: IP Address. . . . . . . . . . . . : 10.0.0.3 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 10.0.0.1 DNS Servers . . . . . . . . . . . : 10.0.0.2 Primary WINS Server . . . . . . . : 10.0.0.2 Installation Notes: Install Windows 2000 Advanced Server into the VM using the default settings except for the manual configuration of the IP settings. Join the machine to the internal.net domain. INTERNAL VPN: Services: No additional network services on installation IP Configuration: Windows 2000 IP Configuration Host Name . . . . . . . . . . . . : INTERNALVPN Primary DNS Suffix . . . . . . . : internal.net DNS Suffix Search List. . . . . . : internal.net Ethernet adapter Local Area Connection (internal adapter): IP Address. . . . . . . . . . . . : 10.0.0.1 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : DNS Servers . . . . . . . . . . . : 10.0.0.2 Primary WINS Server . . . . . . . : 10.0.0.2 Ethernet adapter Local Area Connection 2 (external adapter): IP Address. . . . . . . . . . . . : 192.168.1.125 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : DNS Servers . . . . . . . . . . . : Installation Notes: This machine is dual homed. Use default settings during the Windows 2000 Advanced Server setup in the VM, except for the manual configuration of IP addressing and joining the domain. EXTERNAL VPN: Services: No additional network services on installation IP Configuration: Windows 2000 IP Configuration Host Name . . . . . . . . . . . . : EXTERNALVPN Primary DNS Suffix . . . . . . . : DNS Suffix Search List. . . . . . : Ethernet adapter Local Area Connection (internal adapter): IP Address. . . . . . . . . . . . : 172.16.0.1 Subnet Mask . . . . . . . . . . . : 255.240.0.0 Default Gateway . . . . . . . . . : DNS Servers . . . . . . . . . . . : 172.16.0.2 Primary WINS Server . . . . . . . : 172.16.0.2 Ethernet adapter Local Area Connection 2 (external adapter): IP Address. . . . . . . . . . . . : 192.168.1.126 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : DNS Servers . . . . . . . . . . . : Installation Notes: This machine is dual homed. Use default settings during the Windows 2000 Advanced Server setup in the VM, except for the manual configuration of IP addressing and joining the domain. EXTERNALSRV: Services: All IIS Services DNS --Accepts dynamic updates WINS IP Configuration: Windows 2000 IP Configuration Host Name . . . . . . . . . . . . : EXTERNALSRV Primary DNS Suffix . . . . . . . : DNS Suffix Search List. . . . . . : Ethernet adapter Local Area Connection: IP Address. . . . . . . . . . . . : 172.16.0.2 Subnet Mask . . . . . . . . . . . : 255.240.0.0 Default Gateway . . . . . . . . . : 172.16.0.1 DNS Servers . . . . . . . . . . . : 172.16.0.2 Primary WINS Server . . . . . . . : 172.16.0.2 Installation Notes: Install Windows 2000 Advanced Server into the VM using the default settings except for the manual configuration of the IP settings. The order of installation should be (from first to last): CLIENTDC CERTSRV INTERNALVPN EXTERNALVPN EXTERNALSRV Installing Certificate Server on the Domain Controller To test how to obtain a machine certificate from an Active Directory integrated Enterprise Root Certificate Server, we’ll install Certificate Server on our domain controller, ISACLIENTDC. Perform the following steps to install Certificate Server on the domain controller: Click Start, point to Settings and then click on Control Panel. Open the Add/Remove Programs applet. Click the Add/Remove Windows Components button on the left side of the Add/Remove Programs applet. In the Windows Components Wizard dialog box, place a checkmark in the Certificate Services checkbox. You will get a warning dialog box telling you that you cannot rename the computer or remove or join a domain. Fine. Click Yes, then click Next. If the machine is a Terminal Server (and it is in this lab), you’ll see the Terminal Services Setup dialog box. Select the Remote administration mode and click Next. On the Certification Authority Type page, select the Enterprise root CA option. This option required Active Directory. This is correct option because we want to be able to use the Certificates MMC and/or autoenrollment to install a machine certificate on our ISA/VPN servers. Click Next. On the CA Identifying Information page, fill in all the fields as seen in the figure below. In reality, the only field that’s required is the CA name field. The other’s are optional but it’s a good idea to fill them all in so that you can easily identify the source and purpose of the Certificate Server. Click Next. On the Data Storage Location page, accept the defaults for where you want to put the Certificate database and Certificate Database Log. You have the option to Store configuration information in a shared folder, but this is not required unless you want other CAs in your organization to use this information. Click Next. You will get a warning dialog box informing you that IIS must be stopped before proceeding. Click OK. [...]... that the remote ISA /VPN server be a standalone server that is a member of a workgroup and obtain a machine certificate later We could easily make the remote ISA /VPN server a member of the same domain as our domain controller (CLIENTDC) However, we would have to install the remote ISA /VPN server when it was connected to the local network Then we would make the machine a member of the domain After making... also want a certificate so that the remote file server can use IPSec through the L2TP/IPSec tunnel (VPN IPSec pass-through) We will need to use the Web interface to obtain a certificate for the remote ISA /VPN server because the remote ISA /VPN server is not a member of the domain The remote ISA /VPN server in this lab is configured as a standalone server that is a member of a workgroup Note that it is. .. that IIS must be stopped Insert the CD ROM into the drive when asked Click Finish when the installation is complete Close Close to close the Add/Remove Programs dialog box Obtaining a Certificate from the Standalone Root using the Web Interface The INTERNALVPN, EXTERNALVPN and EXTERNALSRV computers are all going to need a certificate from the standalone root CA We won’t be able to obtain a certificate... that the request was successful Close the Certificates mmc In the dialog box that if you want to save the console settings, click Yes Save the console on the desktop with the name Certificates Installing a Stand-alone Root CA In this section we’ll install a standalone root CA on the CERTSRV computer The reason for the standalone root CA is that we need to install a certificate on the remote ISA /VPN server. .. Certificate Template page, select the Computer certificate template and click Next On the Certificate Authority page, accept the default and click Next On the Completing the Automatic Certificate Request Setup page, click Finish After you complete the Wizard, the Certificate Server will automatically assign machine certificates to all machines in the domain The machines will obtain a certificate during... Information page The only required field is the CA name, but you should include the rest of the information to make it easier to figure out what the CA is for Click Next On the Data Storage Location accept the defaults in this lab You do not need to create a shared folder for storage configuration (I do this out of habit, but it is not required for this lab) Click Next Click OK in the dialog box that... Add Stand-alone Snap-in dialog box, select Certificates and click Add On the This snap-in will always manage certificates for page box, select the Computer account option and click Next In the Select the computer you want this Snap-in to manage page, select the Local computer option and click Finish Click Close in the Add Standalone Snap-in dialog box Click OK in the Add/Remove Snap-in dialog box... see how you can request a certificate from an Enterprise Root CA using the mmc You can use this method if you don’t want to, or can’t, use the autoenrollment Group Policy Be aware that the machine making the request must be a member of the same domain as the Enterprise Root Certificate Server You cannot use this method if the requesting machine is not in the same domain In the Certificates mmc console,... configure domain Group Policy to autoenroll domain members so that they automatically receive a machine certificate: Click Start, point to Programs and point to Administrative Tools Click on Active Directory Users and Computers In the Active Directory Users and Computers console, right click on your domain and click Properties On the domain Properties dialog box, click on the Group Policy tab On the Group... the machine a member of the domain, we could take advantage of autoenrollment, or use the Certificates mmc Then we leave the machine as a member of the same domain, or remove the machine from the domain and move it to the remote site The certificate will see be in place even if the machine is removed from the domain On the CERTSRV machine, perform the following steps to install the standalone root CA . Configuring a gateway to gateway VPN is easy using ISA Server. The reason why it’s so easy is that the Local and Remote VPN Wizards make the setup a. Interface By the end of this two part lab, you’ll be the ISA /VPN L2TP/IPSec gateway to gateway Wizard! The Lab Network The graphic below shows the lab network: