Accessing the guest OS from the host using VirtualBox

To be able to access the guest OS via ssh fro the host, type the following on the host

$ VBoxManage setextradata Centos\ 5.3\ x86\ bis "VBoxInternal/Devices/pcnet/0/LUN#0/Config/SSH/HostPort" 3333
 $ VBoxManage setextradata Centos\ 5.3\ x86\ bis "VBoxInternal/Devices/pcnet/0/LUN#0/Config/SSH/GuestPort" 22
$ VBoxManage setextradata Centos\ 5.3\ x86\ bis "VBoxInternal/Devices/pcnet/0/LUN#0/Config/SSH/Protocol" TCP

(SSH is just a string, you can type anything really). Then you can login to the guest OS by typing this on the host:

$ ssh -p 2222 -X root@localhost

note the same principle applies to other services, example for httpd:

$ VBoxManage setextradata GuestName "VBoxInternal/Devices/pcnet/0/LUN#0/Config/Apache/HostPort" 8888
$ VBoxManage setextradata GuestName "VBoxInternal/Devices/pcnet/0/LUN#0/Config/Apache/GuestPort" 80
$ VBoxManage setextradata GuestName "VBoxInternal/Devices/pcnet/0/LUN#0/Config/Apache/Protocol" TCP

then you can point the host browser to http://localhost:8888. Note that you can’t use a host port lower than 1024 without running VirtualBox with escalated privileges.

To see settings use:

$ VBoxManage getextradata guestname enumerate

To clear a setting (by giving it a clear value) use:

$ VBoxManage setextradata "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/GuestPort"

Virtual lab with VirtualBox

To get two virtual guests to talk to each other while also being able to reach out to rpm repos etc. (i.e.  to inernet), one needs to define two interfaces on the VirtualBox guest OS settings:

• first interface (will be eth0) should use default NAT setting. This will provide Internet access.
• second interface (will be eth1) should use 'Internal Network'. This will provide in-between guests connectivity.

When booting the guest (Centos in my case), eth0 will come up via DHCP, then configure eth1 with a static non routable IP address. However when bringing it up, it will override DNS and default GW as set by eth0, therefore breaking internet access. The fastest path recover is to simply restart eth0 (ifdown eth0/ifup eth0) which gets again the correct settings from the dhcp server.