How to access Oracle VM virtualmachine's database from local computer in Visual Studio

Question

The problem is unrelated to VS,
you need to make sure the network device you installed is reachable from the outer world, and that there is a route from your machine to the VM ip device.
What I write here is the simplest configuration in the case you have a home network...
withing Oracle virtualBox -> choose the VM ->(right click) Settings -> Network.
choose "Bridged Adapter" and select the physical card on your computer.
within the VM make sure the IP address is being taken from DHCP (How to do it depends on the Linux distribution you have).
After doing so - restart the network device within the VM, and make sure both of the machines, the windows and the linux, have the same IP segment, and that ping from the windows can reach the linux VM with Oracle.

If you do not have a home network - The VM added another networking device on your windows machine (if it is hosted on the same machine), which you need to route the trafic to the VM IP to.

If it is not on the same machine - you need to make sure that the router both the machines are connected to knows about the path to the database.

After the networking issue was resolved (and you can practically ping from one machine to the other assuming the firewall allows it),
make sure the listener on the DB machine listens to the right address.
this link will help: http://docs.oracle.com/cd/B28359_01/network.111/b28317/listener.htm

Than you should be done.

Let me know if this wasn't the problem, and your issue is configuring VS - since this is a different issue, which will depend on if your using ODAC or ODT...

Also let me know if you don't know how to check/configure any of the things I wrote above - I didn't write it all since it is long and complicated to answwer all of it in one post...