Mac – Unable to access the internet from the VirtualBox CentOS VM via wireless connection

bridgecentosnetworkingvirtual machinevirtualbox

I have a VirtualBox CentOS VM setup on my Windows 7 machine. I can ping my router, however I am unable to access the outside world.

In Windows I have three network connections setup:

Wireless Network Connection (my WWW connection)
VirtualBox Host-Only Network (my VM)
Local Area Connection (unused)

I have my VM setup to use a bridged adapter to connect through the "Dell Wireless adapter".

Is there any reason why I should be unable to access the outside world from the VM?

I am trying to ping Google with:

ping 8.8.8.8

and getting connect: network is unreachable

This is a dump from ifconfig:

eth0      Link encap:Ethernet  HWaddr 08:00:27:F2:EF:F7  
          inet addr:192.168.0.25  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:3310 errors:0 dropped:0 overruns:0 frame:0
          TX packets:337 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:292875 (286.0 KiB)  TX bytes:40593 (39.6 KiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:249 errors:0 dropped:0 overruns:0 frame:0
          TX packets:249 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:20076 (19.6 KiB)  TX bytes:20076 (19.6 KiB)

Here is a dump from route -n:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth0

Best Answer

Your routing table is incomplete.

Your computer only knows how to route to IPs that start with 192.168 and 169.254 but does not know how to route to any other IPs, we'll want any other IPs to be routed through your router.

If your router would be 192.168.1.1, you can for example execute:

route add default gw 192.168.1.1

This would cause the table to look like this:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth0
0.0.0.0         192.168.1.1     0.0.0.0         UG    0      0        0 eth0

For more information on how this works, execute man route.

Related Solutions

Linux – Unable to ping guest from host and vise versa in Oracle Virtual Box

In most cases the easiest setup is to use NAT and define port forwarding as needed.

For example, a simple Port Forwarding setup allowing connection to the VM from the host through shh on localhost:10022, and to the webserver on localhost:8080would be:

(Name - Protocol - Host IP : Host Port - Guest IP : Guest Port)
SSH - TCP - 127.0.0.1 : 10022 - 10.0.2.15(*) : 22
www - TCP - 127.0.0.1 : 8080 - 10.0.2.15(*) : 80

(*) virtual IP returned by a ifconfig from the VM, most probably different for you.

Should you have special requirements preventing NAT from working, please give some details about what you want to achieve.

Linux Networking – How to Check if Multiple Network Interfaces Are Working

The reason why your bind does not work has nothing to with bind, a trick I use too, and everything to do with the fact that you have only one default gateway, on the usb0 NIC, while you should have one on either NIC, otherwise connection to WAN sites from wlan0 will not be routed.

Linux allows the existence of multiple gateways (one per interface, virtual or not), under the regimen of policy-based routing. What you need to do is to have two separate routing tables, one for usb0 and one for wlan0, and a rule telling the kernel which one to use; then binding an application to either interface will allow you to reach WAN sites.

You handle two routing tables as follows: First, create two tables (Replace and with sensible names, same with IP1, DEV1, and so on):

echo 200 <NAME1> >> /etc/iproute2/rt_tables
echo 201 <NAME2> >> /etc/iproute2/rt_tables

Add a gateway to each routing table (if needed):

ip route add <NET1> dev <DEV1> src <SRC1> table <NAME1>
ip route add <NET2> dev <DEV2> src <SRC2> table <NAME2>

Then a default route:

ip route add default via <IP1> table <NAME1>
ip route add default via <IP2> table <NAME2>

Then the rules to select the route table based on the source address:

ip rule add from <IP1> table <NAME1>
ip rule add from <IP2> table <NAME2>

Now you can bind application to either interface.