There are many reasons you will have for wanting to enable SNMP on your ESX hosts, and a whole slew of applications out there to monitor your environment. I have been playing with the Orion APM module lately, and it is not too bad. The newest version now has some support for virtual hosts, so I figured I would add those to see what kind of goodies they have. These directions may work for other versions of ESX, but these are the only 2 I currently have in my environment and I know this will work for those.
First off, you will need to download the VMware vSphere CLI. This is different from the VMware powershell installation and will allow you to make a run quite a few common commands remotely against your ESX environment from Windows or Linux systems.
Once this is installed, we need to configure your community, string and port to be used. If you are using Windows, you need to launch the CLI and change the directory to the bin folder. Here is the syntax to configure:
-c -p 161 -t @161/
You will be prompted for the root username and password for the ESX host.
Next we will need to enable it:
Again you will be prompted for the root username and password.
Now you should be able to add the host to Orion, or whatever your monitoring application of choice is.