@wcloudme 都开了的，就很神奇，这个 KVM 机器 ping 外界时 tcpdump 没有反应，但是当从外界 ping 进来居然有反应，但是 ping 网关和其它同个内网的 ip 都是不通的。

tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
04:09:58.581732 IP6 fe80::94f1:4dff:fed9:ebe6 > ip6-allnodes: ICMP6, router advertisement, length 72
04:09:58.593846 IP6 fe80::216:3eff:fe2c:10b4 > ff02::16: HBH ICMP6, multicast listener report v2, 2 group record(s), length 48
04:09:58.593846 IP6 fe80::216:3eff:fe89:f9c7 > ff02::16: HBH ICMP6, multicast listener report v2, 2 group record(s), length 48
04:09:58.721851 IP6 fe80::216:3eff:fe2c:10b4 > ff02::16: HBH ICMP6, multicast listener report v2, 2 group record(s), length 48
04:09:59.293867 IP6 fe80::216:3eff:fe89:f9c7 > ff02::16: HBH ICMP6, multicast listener report v2, 2 group record(s), length 48
04:10:45.696347 IP6 fe80::94f1:4dff:fed9:ebe6 > ff02::1:fff7:d55: ICMP6, neighbor solicitation, who has 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:45.696373 IP6 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor advertisement, tgt is 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:46.699606 IP6 fe80::94f1:4dff:fed9:ebe6 > ff02::1:fff7:d55: ICMP6, neighbor solicitation, who has 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:46.699629 IP6 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor advertisement, tgt is 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:47.723576 IP6 fe80::94f1:4dff:fed9:ebe6 > ff02::1:fff7:d55: ICMP6, neighbor solicitation, who has 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:47.723599 IP6 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor advertisement, tgt is 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:48.747932 IP6 fe80::94f1:4dff:fed9:ebe6 > ff02::1:fff7:d55: ICMP6, neighbor solicitation, who has 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:48.747957 IP6 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor advertisement, tgt is 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:49.771669 IP6 fe80::94f1:4dff:fed9:ebe6 > ff02::1:fff7:d55: ICMP6, neighbor solicitation, who has 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:49.771692 IP6 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor advertisement, tgt is 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:50.795669 IP6 fe80::94f1:4dff:fed9:ebe6 > ff02::1:fff7:d55: ICMP6, neighbor solicitation, who has 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:50.795693 IP6 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor advertisement, tgt is 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:50.906757 IP6 fe80::98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor solicitation, who has fe80::94f1:4dff:fed9:ebe6, length 32
04:10:50.930790 IP6 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55.48356 > dns.google.domain: 65104+ PTR? 5.5.d.0.7.f.e.f.f.f.5.1.8.f.8.9.1.f.1.7.d.8.a.1.0.0.a.8.9.0.4.2.ip6.arpa. (90)
04:10:51.930755 IP6 fe80::98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor solicitation, who has fe80::94f1:4dff:fed9:ebe6, length 32
04:10:56.459972 IP6 fe80::94f1:4dff:fed9:ebe6 > ff02::1:fff7:d55: ICMP6, neighbor solicitation, who has 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:56.459994 IP6 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor advertisement, tgt is 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:57.483889 IP6 fe80::94f1:4dff:fed9:ebe6 > ff02::1:fff7:d55: ICMP6, neighbor solicitation, who has 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:57.483913 IP6 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor advertisement, tgt is 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:58.507849 IP6 fe80::94f1:4dff:fed9:ebe6 > ff02::1:fff7:d55: ICMP6, neighbor solicitation, who has 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
04:10:58.507872 IP6 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55 > fe80::94f1:4dff:fed9:ebe6: ICMP6, neighbor advertisement, tgt is 2406:8a55:1a8d:71f1:98f8:15ff:fef7:d55, length 32
^C
26 packets captured
33 packets received by filter
7 packets dropped by kernel