VirtIO Driver Support

The FreeBSD kernel used by pfSense® software includes VirtIO drivers built into the kernel. No special action is necessary to enable the drivers.

Disable Hardware Checksum Offloading

With the current state of VirtIO network drivers in FreeBSD, it is necessary to disable hardware checksum offload to reach systems (at least other VM guests, possibly others) protected by pfSense software directly from the VM host. The firewall attempts to do this automatically when it detects vtnet interfaces, but the setting may also be changed manually under System > Advanced on the Networking tab.

Note

After changing the setting manually reboot the firewall, even though there is no prompt instructing to do so.

The issue is most likely caused by FreeBSD Bug 165059.

Hardware checksums and other NIC offloading features like TSO may also need to be disabled on the hypervisor system in addition to the pfSense VM.