immortal $ tcpdump -i eth1
11:31:29.509923 IP 10.0.0.2.openvpn > 172.16.0.2.openvpn: UDP, length 125
11:31:29.511025 IP 172.16.0.2.openvpn > 10.0.0.2.openvpn: UDP, length 125
immortal $ tcpdump -i tun1
11:36:47.999376 IP 10.0.1.2 > 10.0.1.1: ICMP echo request, id 1569, seq 400, length 64
11:36:47.999395 IP 10.0.1.1 > 10.0.1.2: ICMP echo reply, id 1569, seq 400, length 64