VBoxHeadless reliably eating 100% CPU

[vushakov]

Is IP forwarding turned on in the guest and what is your network configuration on the host and in the guest?

The reason I'm asking is to exclude the routing loop. E.g. if you have a route on the host that points to the guest via the host-only interface and in the guest you don't treat the destination of that route specially you can create a SYN storm.

Let's say on the host you route 1.2.3.0/24 into the guest via host-only. You make a connection from the host to 1.2.3.4. A SYN is sent to the guest. The SYN is forwarded via guest's default route to the NAT connection, which is not really a NAT, but sort of an automagic socks proxy, so NAT does connect(2) on a host socket to 1.2.3.4. Which sends a SYN to the guest via host-only. Etc, etc.

As a variation of this theme, you may, alternatively, run some kind of a proxy in the guest that accepts the connection to 1.2.3.4 and tries to make its own connection to the real 1.2.3.4.

Packet traces of the NAT and host-only connections might be helpful.

And it's probably better to use bug tracker for this.

[mightyiam]

@vushakov, I made a ticket.

I hope I've answered the questions sufficiently there.

[vushakov]

@vushakov, I made a ticket.

Have you set up email notifications for the tracker? It's opt-in. In the bug report I've asked for packet traces.