When attempting to add host-level credentials in vRanger, the attempt fails with the error "Error - 403 Forbidden"
This is an HTTP error when the vRanger machine is attempting to establish communication to the Managed Object Browser (MOB) of the ESX(i) Host machine over port 443 (SSL). Usually, this is due to a proxy server being enabled (443 is a commonly-redirected web port, since it is used for SSL (Secured-Sockets Layer) communications (https protocol). Firewalls also commonly block/translate this port in certain environments.
1) Verify Windows Firewall/other 3rd-party firewall software is not blocking two-way port-443 traffic to/from the vRanger machine and the host in question.
2) Once that is verified, check the Internet Options-->Connections--->LAN Settings--->Proxy Server Settings (variously labeled in different OS versions). Make sure the vRanger machine is NOT using a proxy server, and the "Automatically" detect settings" box is NOT checked.
3) Sometimes, these settings may not be changed if they are defined as part of a Group Policy Object (GPO) -- hence, they are automatically (and forcibly assigned to) the machine and/or logged-in user. If this is the case, consult with your Active Directory administrative personnel to except the vRanger machine from the rule "pushing" the Proxy settings to it.
4) If the settings are able to be changed, but the error still results, malware or other software may have altered where the Windows OS is retrieving the proxy settings (e.g. to redirect browsing sessions to an ad-ware page, etc.) If this is the case, the proxy setting must be reverted to the Microsoft standard locale, then disabled. Consult the following Microsoft KB to see how to manipulate the Windows Registry to accomplish this: