Network tracing

Network problems could be detected by enabling packet logging at the guest side or the host side, but using the built-in capability of VirtualBox to create pcap files might provide even more useful information because it contains a log of really all packets received and sent by guest.

To enable network tracing do the following:

# VBoxManage modify [your-vm] -nictrace[adapter-number] on -nictracefile[adapter-number] file.pcap
# VirtualBox -startvm [your-vm]

For example

# VBoxManage modify "ubuntu" -nictrace1 on -nictracefile1 file.pcap
# VirtualBox -startvm "ubuntu"

Note: Don't forget to disable tracing because your hard disk will quickly be filled by pcap files in case of intensive network usage. The port-forwarding configuration might be affected by this setting as well.