As you know you can easily integrate SCOM with System Center Virtual Machine Manager (SCVMM). If both system live in the same forest this is not a problem and you can find all the steps here. What happen if one system lives in a separated trusted forest which has a firewall in between? For integrating SCVMM into SCOM you run the SCVMM connector wizard. So the connection starts from SCVMM to SCOM. On the firewall we could see a blocking connection on port 5724/TCP from SCVMM to SCOM. This means, the only port used for SCVMM connector is 5724/TCP, which is by the way the same port as the SCOM console uses for connecting to a SCOM management server. We opened that port and the SCVMM integration into SCOM ended successfully.
For all other firewall exceptions, see the list provided on TechNet.