Tinc Router Mode - PING RESULT is destination host unreachable

Sat Feb 13 18:26:22 CET 2016

Hi Lars,

I have no experience to use tcpdump, here is the output from TCPdump for
your reference. Any idea?

Use my home PC to ping company PC

01:00:25.154706 ethertype IPv4, IP 192.168.1.2 > 10.0.0.2: ICMP echo
request, id 1, seq 17, length 40
01:00:25.154706 IP 192.168.1.2 > 10.0.0.2: ICMP echo request, id 1, seq 17,
length 40
01:00:25.154706 IP 192.168.1.2 > 10.0.0.2: ICMP echo request, id 1, seq 17,
length 40
01:00:25.155177 IP 192.168.1.1 > 192.168.1.2: ICMP 10.0.0.2 protocol 1 port
19786 unreachable, length 68
01:00:25.155225 IP 192.168.1.1 > 192.168.1.2: ICMP 10.0.0.2 protocol 1 port
19786 unreachable, length 68
01:00:26.157248 ethertype IPv4, IP 192.168.1.2 > 10.0.0.2: ICMP echo
request, id 1, seq 18, length 40
01:00:26.157248 IP 192.168.1.2 > 10.0.0.2: ICMP echo request, id 1, seq 18,
length 40
01:00:26.157248 IP 192.168.1.2 > 10.0.0.2: ICMP echo request, id 1, seq 18,
length 40
01:00:26.157711 IP 192.168.1.1 > 192.168.1.2: ICMP 10.0.0.2 protocol 1 port
19785 unreachable, length 68
01:00:26.157756 IP 192.168.1.1 > 192.168.1.2: ICMP 10.0.0.2 protocol 1 port
19785 unreachable, length 68
01:00:27.159698 ethertype IPv4, IP 192.168.1.2 > 10.0.0.2: ICMP echo
request, id 1, seq 19, length 40
01:00:27.159698 IP 192.168.1.2 > 10.0.0.2: ICMP echo request, id 1, seq 19,
length 40
01:00:27.159698 IP 192.168.1.2 > 10.0.0.2: ICMP echo request, id 1, seq 19,
length 40
01:00:27.160165 IP 192.168.1.1 > 192.168.1.2: ICMP 10.0.0.2 protocol 1 port
19784 unreachable, length 68
01:00:27.160211 IP 192.168.1.1 > 192.168.1.2: ICMP 10.0.0.2 protocol 1 port
19784 unreachable, length 68
01:00:28.163041 ethertype IPv4, IP 192.168.1.2 > 10.0.0.2: ICMP echo
request, id 1, seq 20, length 40
01:00:28.163041 IP 192.168.1.2 > 10.0.0.2: ICMP echo request, id 1, seq 20,
length 40
01:00:28.163041 IP 192.168.1.2 > 10.0.0.2: ICMP echo request, id 1, seq 20,
length 40
01:00:28.163506 IP 192.168.1.1 > 192.168.1.2: ICMP 10.0.0.2 protocol 1 port
19783 unreachable, length 68
01:00:28.163551 IP 192.168.1.1 > 192.168.1.2: ICMP 10.0.0.2 protocol 1 port
19783 unreachable, length 68
01:00:30.557443 ethertype IPv4, IP 192.168.1.2 > 10.0.0.1: ICMP echo
request, id 1, seq 21, length 40
01:00:30.557443 IP 192.168.1.2 > 10.0.0.1: ICMP echo request, id 1, seq 21,
length 40
01:00:30.557443 IP 192.168.1.2 > 10.0.0.1: ICMP echo request, id 1, seq 21,
length 40
01:00:30.557881 IP 10.0.0.1 > 192.168.1.2: ICMP echo reply, id 1, seq 21,
length 40
01:00:30.557927 IP 10.0.0.1 > 192.168.1.2: ICMP echo reply, id 1, seq 21,
length 40
01:00:31.560697 ethertype IPv4, IP 192.168.1.2 > 10.0.0.1: ICMP echo
request, id 1, seq 22, length 40
01:00:31.560697 IP 192.168.1.2 > 10.0.0.1: ICMP echo request, id 1, seq 22,
length 40
01:00:31.560697 IP 192.168.1.2 > 10.0.0.1: ICMP echo request, id 1, seq 22,
length 40
01:00:31.561039 IP 10.0.0.1 > 192.168.1.2: ICMP echo reply, id 1, seq 22,
length 40
01:00:31.561079 IP 10.0.0.1 > 192.168.1.2: ICMP echo reply, id 1, seq 22,
length 40
01:00:32.565071 ethertype IPv4, IP 192.168.1.2 > 10.0.0.1: ICMP echo
request, id 1, seq 23, length 40
01:00:32.565071 IP 192.168.1.2 > 10.0.0.1: ICMP echo request, id 1, seq 23,
length 40
01:00:32.565071 IP 192.168.1.2 > 10.0.0.1: ICMP echo request, id 1, seq 23,
length 40
01:00:32.565410 IP 10.0.0.1 > 192.168.1.2: ICMP echo reply, id 1, seq 23,
length 40
01:00:32.565451 IP 10.0.0.1 > 192.168.1.2: ICMP echo reply, id 1, seq 23,
length 40
01:00:33.569452 ethertype IPv4, IP 192.168.1.2 > 10.0.0.1: ICMP echo
request, id 1, seq 24, length 40
01:00:33.569452 IP 192.168.1.2 > 10.0.0.1: ICMP echo request, id 1, seq 24,
length 40
01:00:33.569452 IP 192.168.1.2 > 10.0.0.1: ICMP echo request, id 1, seq 24,
length 40
01:00:33.569877 IP 10.0.0.1 > 192.168.1.2: ICMP echo reply, id 1, seq 24,
length 40
01:00:33.569918 IP 10.0.0.1 > 192.168.1.2: ICMP echo reply, id 1, seq 24,
length 40
01:00:35.242556 ethertype IPv4, IP 192.168.1.2 > 192.168.2.1: ICMP echo
request, id 1, seq 25, length 40
01:00:35.242556 IP 192.168.1.2 > 192.168.2.1: ICMP echo request, id 1, seq
25, length 40
01:00:35.242556 IP 192.168.1.2 > 192.168.2.1: ICMP echo request, id 1, seq
25, length 40
01:00:35.243018 IP 192.168.1.1 > 192.168.1.2: ICMP 192.168.2.1 protocol 1
port 19778 unreachable, length 68
01:00:35.243063 IP 192.168.1.1 > 192.168.1.2: ICMP 192.168.2.1 protocol 1
port 19778 unreachable, length 68
01:00:36.244070 ethertype IPv4, IP 192.168.1.2 > 192.168.2.1: ICMP echo
request, id 1, seq 26, length 40
01:00:36.244070 IP 192.168.1.2 > 192.168.2.1: ICMP echo request, id 1, seq
26, length 40
01:00:36.244070 IP 192.168.1.2 > 192.168.2.1: ICMP echo request, id 1, seq
26, length 40
01:00:36.244548 IP 192.168.1.1 > 192.168.1.2: ICMP 192.168.2.1 protocol 1
port 19777 unreachable, length 68
01:00:36.244593 IP 192.168.1.1 > 192.168.1.2: ICMP 192.168.2.1 protocol 1
port 19777 unreachable, length 68
01:00:37.246363 ethertype IPv4, IP 192.168.1.2 > 192.168.2.1: ICMP echo
request, id 1, seq 27, length 40
01:00:37.246363 IP 192.168.1.2 > 192.168.2.1: ICMP echo request, id 1, seq
27, length 40
01:00:37.246363 IP 192.168.1.2 > 192.168.2.1: ICMP echo request, id 1, seq
27, length 40
01:00:37.246823 IP 192.168.1.1 > 192.168.1.2: ICMP 192.168.2.1 protocol 1
port 19776 unreachable, length 68
01:00:37.246868 IP 192.168.1.1 > 192.168.1.2: ICMP 192.168.2.1 protocol 1
port 19776 unreachable, length 68
01:00:38.248812 ethertype IPv4, IP 192.168.1.2 > 192.168.2.1: ICMP echo
request, id 1, seq 28, length 40
01:00:38.248812 IP 192.168.1.2 > 192.168.2.1: ICMP echo request, id 1, seq
28, length 40
01:00:38.248812 IP 192.168.1.2 > 192.168.2.1: ICMP echo request, id 1, seq
28, length 40
01:00:38.249276 IP 192.168.1.1 > 192.168.1.2: ICMP 192.168.2.1 protocol 1
port 19775 unreachable, length 68
01:00:38.249322 IP 192.168.1.1 > 192.168.1.2: ICMP 192.168.2.1 protocol 1
port 19775 unreachable, length 68

Use OpenWrt router to ping

01:17:15.231056 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:16.555266 IP 10.0.0.1 > 10.0.0.1: ICMP echo request, id 24869, seq 0,
length 64
01:17:16.555514 IP 10.0.0.1 > 10.0.0.1: ICMP echo reply, id 24869, seq 0,
length 64
01:17:16.590838 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:17.556106 IP 10.0.0.1 > 10.0.0.1: ICMP echo request, id 24869, seq 1,
length 64
01:17:17.556345 IP 10.0.0.1 > 10.0.0.1: ICMP echo reply, id 24869, seq 1,
length 64
01:17:17.775263 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:17.783452 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:18.556830 IP 10.0.0.1 > 10.0.0.1: ICMP echo request, id 24869, seq 2,
length 64
01:17:18.557059 IP 10.0.0.1 > 10.0.0.1: ICMP echo reply, id 24869, seq 2,
length 64
01:17:19.557536 IP 10.0.0.1 > 10.0.0.1: ICMP echo request, id 24869, seq 3,
length 64
01:17:19.557777 IP 10.0.0.1 > 10.0.0.1: ICMP echo reply, id 24869, seq 3,
length 64
01:17:20.295382 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:20.310048 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:21.512500 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:21.653524 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:21.669882 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:22.772178 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:24.715863 IP 10.0.0.1 > 10.0.0.2: ICMP echo request, id 25125, seq 0,
length 64
01:17:24.867369 IP 10.0.0.2 > 10.0.0.1: ICMP echo reply, id 25125, seq 0,
length 64
01:17:24.880975 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:25.721487 IP 10.0.0.1 > 10.0.0.2: ICMP echo request, id 25125, seq 1,
length 64
01:17:25.838114 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:25.840444 IP 10.0.0.2 > 10.0.0.1: ICMP echo reply, id 25125, seq 1,
length 64
01:17:25.848984 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:26.721920 IP 10.0.0.1 > 10.0.0.2: ICMP echo request, id 25125, seq 2,
length 64
01:17:26.775946 IP 10.0.0.2 > 10.0.0.1: ICMP echo reply, id 25125, seq 2,
length 64
01:17:27.722331 IP 10.0.0.1 > 10.0.0.2: ICMP echo request, id 25125, seq 3,
length 64
01:17:27.817985 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:27.823082 IP 10.0.0.2 > 10.0.0.1: ICMP echo reply, id 25125, seq 3,
length 64
01:17:31.580234 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:31.595471 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:31.640342 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:33.970715 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:33.978216 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:36.479992 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:36.645113 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:17:37.717665 IP 10.0.0.1 > 192.168.2.1: ICMP echo request, id 25381, seq
0, length 64
01:17:37.915851 IP 192.168.2.1 > 10.0.0.1: ICMP echo reply, id 25381, seq 0,
length 64
01:17:38.718179 IP 10.0.0.1 > 192.168.2.1: ICMP echo request, id 25381, seq
1, length 64
01:17:38.805564 IP 192.168.2.1 > 10.0.0.1: ICMP echo reply, id 25381, seq 1,
length 64
01:17:39.718578 IP 10.0.0.1 > 192.168.2.1: ICMP echo request, id 25381, seq
2, length 64
01:17:39.804755 IP 192.168.2.1 > 10.0.0.1: ICMP echo reply, id 25381, seq 2,
length 64
01:17:40.718980 IP 10.0.0.1 > 192.168.2.1: ICMP echo request, id 25381, seq
3, length 64
01:17:40.802417 IP 192.168.2.1 > 10.0.0.1: ICMP echo reply, id 25381, seq 3,
length 64
01:17:48.361731 IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 25637,
seq 0, length 64
01:17:48.361801 IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 25637,
seq 0, length 64
01:17:48.363071 ethertype IPv4, IP 192.168.1.2 > 192.168.1.1: ICMP echo
reply, id 25637, seq 0, length 64
01:17:48.363071 IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 25637, seq
0, length 64
01:17:48.363071 IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 25637, seq
0, length 64
01:17:49.362327 IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 25637,
seq 1, length 64
01:17:49.362391 IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 25637,
seq 1, length 64
01:17:49.363405 ethertype IPv4, IP 192.168.1.2 > 192.168.1.1: ICMP echo
reply, id 25637, seq 1, length 64
01:17:49.363405 IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 25637, seq
1, length 64
01:17:49.363405 IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 25637, seq
1, length 64
01:17:50.362884 IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 25637,
seq 2, length 64
01:17:50.362952 IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 25637,
seq 2, length 64
01:17:50.364043 ethertype IPv4, IP 192.168.1.2 > 192.168.1.1: ICMP echo
reply, id 25637, seq 2, length 64
01:17:50.364043 IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 25637, seq
2, length 64
01:17:50.364043 IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 25637, seq
2, length 64
01:17:51.363467 IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 25637,
seq 3, length 64
01:17:51.363533 IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 25637,
seq 3, length 64
01:17:51.364624 ethertype IPv4, IP 192.168.1.2 > 192.168.1.1: ICMP echo
reply, id 25637, seq 3, length 64
01:17:51.364624 IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 25637, seq
3, length 64
01:17:51.364624 IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 25637, seq
3, length 64

Use company PC to ping

01:23:03.327966 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:04.816391 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:05.211811 IP 10.0.0.2 > 192.168.1.1: ICMP echo request, id 1, seq
2853, length 40
01:23:05.212180 IP 192.168.1.1 > 10.0.0.2: ICMP echo reply, id 1, seq 2853,
length 40
01:23:05.228221 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:06.200953 IP 10.0.0.2 > 192.168.1.1: ICMP echo request, id 1, seq
2854, length 40
01:23:06.201255 IP 192.168.1.1 > 10.0.0.2: ICMP echo reply, id 1, seq 2854,
length 40
01:23:06.289783 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:07.350522 IP 10.0.0.2 > 192.168.1.1: ICMP echo request, id 1, seq
2855, length 40
01:23:07.350827 IP 192.168.1.1 > 10.0.0.2: ICMP echo reply, id 1, seq 2855,
length 40
01:23:09.449526 IP 10.0.0.2 > 192.168.1.1: ICMP echo request, id 1, seq
2856, length 40
01:23:09.449832 IP 192.168.1.1 > 10.0.0.2: ICMP echo reply, id 1, seq 2856,
length 40
01:23:09.725296 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:11.425411 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:12.237556 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:12.262528 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:13.651353 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:13.715695 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:15.982798 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:16.007804 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:16.156518 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:16.165304 IP 10.0.0.2 > 10.0.0.1: ICMP echo request, id 1, seq 2857,
length 40
01:23:16.165707 IP 10.0.0.1 > 10.0.0.2: ICMP echo reply, id 1, seq 2857,
length 40
01:23:17.150963 IP 10.0.0.2 > 10.0.0.1: ICMP echo request, id 1, seq 2858,
length 40
01:23:17.151264 IP 10.0.0.1 > 10.0.0.2: ICMP echo reply, id 1, seq 2858,
length 40
01:23:18.156261 IP 10.0.0.2 > 10.0.0.1: ICMP echo request, id 1, seq 2859,
length 40
01:23:18.156564 IP 10.0.0.1 > 10.0.0.2: ICMP echo reply, id 1, seq 2859,
length 40
01:23:19.157767 IP 10.0.0.2 > 10.0.0.1: ICMP echo request, id 1, seq 2860,
length 40
01:23:19.158072 IP 10.0.0.1 > 10.0.0.2: ICMP echo reply, id 1, seq 2860,
length 40
01:23:20.509029 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:21.669120 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:22.895954 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:25.466373 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:27.930107 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:27.938637 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:28.176923 IP 192.168.1.1 > 192.168.1.1: ICMP 218.188.88.37 unreachable
- need to frag (mtu 1480), length 556
01:23:29.808414 IP 10.0.0.2 > 192.168.1.2: ICMP echo request, id 1, seq
2865, length 40
01:23:29.808828 IP 10.0.0.1 > 10.0.0.2: ICMP 192.168.1.2 protocol 1 port
16938 unreachable, length 68
01:23:30.835163 IP 10.0.0.2 > 192.168.1.2: ICMP echo request, id 1, seq
2866, length 40
01:23:30.835578 IP 10.0.0.1 > 10.0.0.2: ICMP 192.168.1.2 protocol 1 port
16937 unreachable, length 68
01:23:31.831244 IP 10.0.0.2 > 192.168.1.2: ICMP echo request, id 1, seq
2867, length 40
01:23:31.831657 IP 10.0.0.1 > 10.0.0.2: ICMP 192.168.1.2 protocol 1 port
16936 unreachable, length 68
01:23:32.832992 IP 10.0.0.2 > 192.168.1.2: ICMP echo request, id 1, seq
2868, length 40
01:23:32.833452 IP 10.0.0.1 > 10.0.0.2: ICMP 192.168.1.2 protocol 1 port
16935 unreachable, length 68

Regards,
Eric

-----Original Message-----
From: Lars Kruse [mailto:lists at sumpfralle.de] 
Sent: Saturday, February 13, 2016 1:24 AM
To: tinc at tinc-vpn.org
Subject: Re: Tinc Router Mode - PING RESULT is destination host unreachable

Hi Eric,

Am Fri, 12 Feb 2016 23:51:59 +0800
schrieb Eric Yau <ericyaukhy at hotmail.com>:

> [..]
> Question: On home side (OpenWrt Router) and company side (Windows 7 
> PC), I can ping all the IP addresses. But on Home PC (Behind the 
> OPENWRT Router), I cannot ping to Company (Windows 7 PC) and Company 
> (Server A). The PING RESULT is destination host unreachable. Any idea
about that?

at this point I would usually try to find out the following details:
* does the ping packet reach its target?
* does the request packet contain the expected source address?
* is a response packet generated?
* does the response packet go through the expected stations?

All of the above questions can be answered by running tcpdump (e.g. "tcpdump
-ni any icmp") on the machine in question.

It will probably boil down to a routing/nat or a firewall (iptables) issue,
I guess. The "destination host unreachable" error message should indicate
which host fails or refuses to deliver the packet.

Cheers,
Lars