Unable to connect to internet with VirtualBox using bridged adapter

Paravirtualized Network* (virtio-net) is the key

1. select your vm that you want for port forwarding.

   • NOTE: Make sure the vm is in stop mode.

2. Select “Settings"

3. Select “Network"
4. Select any free Adapter. Lets say "Adapter 2"
5. Enable "Enable Network Adapter"
6. In Attached to dropdown, select "NAT"
7. Select "Advanced"
8. In Adapter Type: Select “Paravirtualized Network (virtio-net)” [ This is important ]
9. Select “Port Forwarding"
10. In Right hand part of the “port forwarding” dialog box, select “+"

11. Provide the

    • Name: Anything you want. example for ssh, say “ssh"
    • Protocol: Type of protocol [ for ssh: TCP ]
    • Host IP: provide hostname from which host you want to connect to [ over here: 127.0.0.1 ]
    • Host Port: On what port of that Host you want to connect to remote port [ example: 60022 ]
    • Guest IP: Leave it Blank
    • Guest Port: To what port you want to connect from the above host. [ for ssh, the default 22 ]

This is too long to explain in a comment. Below is how the bridged adapter works.

Yet, if you can ping from the guest debian that means some form of DHCP happened and you must have and IP (which is a different IP from the host machine). I'd check router configuration to see if you're not allowing/disallowing specific MACs and/or IPs from the usage of TCP/UDP protocols (that is a measure some people use on their routers).

Bridged adapter

A bridged adapter on VirtualBox simulates as if there was a bridge (well it is easier to think of this as a hub) on the cable connection to your (host) actual machine. Even if the connection is over wireless the simulation is similar.

For (almost) all purposes the guest (debian) and the router the host machine is connected to are connected directly. Have separate MAC, separate IP, they even give separate ARP requests.

router <---> host machine running VirtualBox
  ^
  |
  +-----> guest machine running Debian

This is done by sending packets with a different hardware address (you can configure the hardware address in the adapter).

You need to configure the guest system (Debian) to connect to the network as if it was a separate machine. For example, if you use a WPA connection from the host machine you need to configure WPA (including the username and password) in the guest machine.