// we should get the fd to dev null. note that we can't assert the fd number
	// as the kernel may have given us a different number that refers to the same file.
	assert.Equal(t, len(fds), 1)
	// in theory we should close the fd, but it's just a test..

	assert.Equal(t, m.Payload.(*zdsapi.WorkloadRequest_Add).Add.Uid, uid)
	// send ack so the server doesn't wait for us.
	sendAck(ztunClient)