Ок.
Делаю на клиенте:
tcpdump -i ppp0 -p icmp -vvnnc6
и пингуюсь с севера к клиенту
вывод tcpdump на клиенте:
tcpdump: listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 262144 bytes
18:02:07.343356 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3327, seq 1, length 64
18:02:08.344321 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3327, seq 2, length 64
18:02:09.344686 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3327, seq 3, length 64
18:02:10.350077 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3327, seq 4, length 64
18:02:11.344819 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3327, seq 5, length 64
18:02:12.348272 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3327, seq 6, length 64
6 packets captured
6 packets received by filter
0 packets dropped by kernel
и вывод tcpdump у сервера
tcpdump: listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 262144 bytes
11:07:14.320423 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3354, seq 2, length 64
11:07:15.320424 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3354, seq 3, length 64
11:07:16.320685 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3354, seq 4, length 64
11:07:17.320425 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3354, seq 5, length 64
11:07:18.320443 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3354, seq 6, length 64
11:07:19.320422 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
81.4.101.142 > 192.168.10.1: ICMP echo request, id 3354, seq 7, length 64
6 packets captured
7 packets received by filter
0 packets dropped by kernel