We've got an existing Virtual Network in Azure, with a site-to-site connection to a 3rd party (X).
An Ubuntu VM is deployed in the network, and can ping/access all resources hosted by X through the site-to-site connection.
I have configured an Azure Certificate point-to-site, downloaded the VPN client, and successfully connected from the client machine.
I need clients to be able to access resources hosted by X, while connected to the VPN, from their local machines; without needing to remote into the Ubuntu box mentioned above.
Over the VPN, the client can ping the Ubuntu box private IP - but cannot access the resources hosted by X
I am a networking newbie - is what I am trying to do possible?
Probably, you could add the route for both X and your clients.
You can type route print in the command prompt to find if there is a route to the 3rd party network. Also, adjust the on-premise site-to-site routing to include the Azure P2S subnet(address pool). You could read this1 and this2 for more details.