HostOnly

Host-only is a term used to describe a type of virtual networking that creates a private network between the host computer and its virtual machines (VMs). In a host-only network, the VMs can communicate with the host and with each other, but have no direct access to external networks unless additional routing or bridging is configured. This setup contrasts with NAT or bridged networking, which provide VMs with access to external networks.

Implementation and components

Virtualization platforms implement host-only networks by adding a virtual switch or adapter on the host. Each VM connects to this virtual network via its own virtual network adapter. The host typically runs a DHCP server for the private subnet, automatically assigning IP addresses to the VMs; static IPs can also be configured. The host itself is reachable from the VMs, enabling management and file sharing within the private network.

Common configurations

Default subnets vary by platform, with VirtualBox commonly using 192.168.56.0/24 and VMware products using other private ranges. Administrators may adjust IP ranges, DHCP settings, and firewall rules to suit specific testing or development needs.

Use cases

Host-only networking is used for isolated development and testing environments, demonstration of network services, and scenarios where VM-to-host communication is required but external network exposure is undesired. It supports secure, repeatable lab setups and reduces risk when experimenting with network configurations or software.

Limitations

The main limitation is lack of direct internet access for VMs. To reach external services, users must add a NAT or bridging connection in addition to the host-only network or enable selective routing between networks.