OpenVPN : Unable to obtain Session ID XML-RPC: TimeoutError or 400 Bad Request

By | February 6, 2012

Using OpenVPN Server on Linux as well as Windows machine, you may encounter this error trying to connect a client :

Unable to obtain Session ID from “vpn.domain.tld”, port(s)=443: XML-RPC: TimeoutError

Unable to obtain Session ID from “vpn.domain.tld”, port(s)=443: XML-RPC: ‘400’, ‘Bad Request’

This happen because HTTPS (SSL) port (TCP-443) is closed either on the server or firewall (server-side).

You also need the following ports open in order to get OpenVPN working :

TCP-943
TCP-1194
UDP-1194