Microsoft System Center Virtual Machine Manager 2008 (VMM) is Microsoft's platform for virtualization management. VMM offers a host of enterprise-level virtualization management capabilities that go far beyond the features in the more basic Hyper-V Manager. VMM is a complex product with many different connected components. Knowing what's actually going on under the hood in VMM is important when it comes to solving problems because each of the VMM components relies on specific TCP/IP ports in order to communicate with other components. If these ports aren't available when called upon, select pieces of VMM functionality won't be available. If there's a network firewall between systems or if you're using Windows Firewall, you need to make sure these ports are available. In this column I'll list the top 10 TCP/IP ports used by VMM and explain what they're used for. Bear in mind these are the default port settings; all the port settings can be customized. For a complete list of the ports and protocols used by VMM, refer to the TechNet article "VMM Ports and Protocols."

1. Administrator Console to VMM server, Port: 8100; Protocol: WCF—The VMM Administrator Console and the VMM server can be installed on the same server, or you can manage the VMM server remotely. For remote management, you need to have port 8100 open on the VMM server.

2. VMM server to VMM agents, Port: 80; Protocol: WinRM (control); Port: 443; Protocol: SMB (data)—VMM uses agents on the target hosts in order to manage them. The VMM agents uses port 80 for management tasks such as viewing or changing the state of your virtual machines (VMs) and port 443 for data transfers to the VMM server.

3. VMM library server to Hyper-V hosts, Port: 443; Protocol: BITS—The VMM library server stores VM templates and stores gold image VM and Virtual Hard Disk (VHD) files that the VMM administrator can use to rapidly create new VMs. A gold image is an OS image that you use as a basis for deploying new systems. The VMM server uses port 443 to transfer these files to the Hyper-V host.

4. VMM server to Microsoft SQL Server database storage, Port: 1433; Protocol: T-SQL—VMM uses SQL Server as a back-end data store. This SQL Server instance can be on the same system as the VMM server, or it can instead be a preexisting SQL Server instance. VMM uses port 1433 to access a networked SQL Server system.

5. VMConnect to Hyper-V hosts, Port: 2179; Protocol: RDP—VMConnect is an application that's part of Hyper-V Manager and VMM; it lets you connect to a console session of a Hyper-V VM. By default VMConnect uses port 2179.

6. VMM Self-Service Web Portal to VMM server, Port: 8100; Protocol: WCF—In addition to the VMM Administrator Console, VMM provides a web-based portal that enables end users to manage their own VMs. The web-based portal must be installed on a system that has Microsoft IIS, and it uses the same port as the Administrator Console, port 8100, to communicate to the VMM server.

7. Remote Desktop to Hyper-V VMs, Port: 3389; Protocol: RDP—Another important protocol for managing VMs is the standard Remote Desktop Protocol. RDP is a staple in my VM management; I have one or more RDP sessions going to my VMs almost all day. RDP uses port 3389.

8. VMM server to VMware vCenter (administration), Port: 443; Protocol: HTTPS—The release of VMM 2008 added support for managing VMware's ESX Server via an instance of VMware vCenter Server. The VMM server communicates with vCenter Server over port 443.

9. VMM server to ESX 3.0 and 3.5 file transfer, Port: 22; Protocol: SFTP—The VMM server can also conduct file transfers directly with ESX Server 3.5 and ESX Server 3.0. These versions of ESX Server use the SFTP protocol over port 22 for remote file access.

10. VMM server to ESXi file transfer, Port: 443; Protocol: SSH/HTTPS—The free version of VMware's virtualization server, ESXi, uses a different port for file transfers. The VMM server communicates with ESXi hosts through port 443, and it uses both SSH and HTTPS.