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Cannot ping6

Hi,

I'm having a network problem with my Fedora 24 Workstation. I cannot ping6 other hosts in the same LAN or on the Internet because it fails with Address unreachable. From other machine in the same LAN (F24 Server) it works fine. In the tcpdump I have the impression that the neighbor solicitations don't succeed. The IPv6 is otherwise working fine as I can do browsing, P2P and everything on it.

I'm going to show you my tests to see if anyone can give me any hint.

$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enp5s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br-lan state UP group default qlen 1000
    link/ether f4:6d:04:61:ab:b4 brd ff:ff:ff:ff:ff:ff
3: br-lan: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether f4:6d:04:61:ab:b4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.100/24 brd 192.168.10.255 scope global br-lan
       valid_lft forever preferred_lft forever
    inet6 2001:470:7950:10::100/64 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::108f:1ae:a4ba:a348/64 scope link
       valid_lft forever preferred_lft forever
4: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
    inet 192.168.124.1/24 brd 192.168.124.255 scope global virbr0
       valid_lft forever preferred_lft forever
5: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
    link/ether 52:54:00:6e:af:89 brd ff:ff:ff:ff:ff:ff

$ ip -6 r
2001:470:7950:10::/64 dev br-lan  proto kernel  metric 256  pref medium
fe80::/64 dev br-lan  proto kernel  metric 256  pref medium
default via 2001:470:7950:10::1 dev br-lan  proto static  metric 425  pref medium

# brctl show
bridge name     bridge id               STP enabled     interfaces
br-lan          8000.f46d0461abb4       yes             enp5s0
virbr0          8000.000000000000       yes

# firewall-cmd --list-all
FedoraWorkstation (default, active)
  interfaces: br-lan enp5s0
  sources:
  services: dhcpv6-client mdns samba samba-client ssh
  ports: 5298/tcp 1900/udp 8333/tcp 8200/tcp
  protocols:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:

 $ ping6 -n www.google.com
PING www.google.com(2a00:1450:4003:808::2004) 56 data bytes
From 2001:470:7950:10::100 icmp_seq=1 Destination unreachable: Address unreachable
From 2001:470:7950:10::100 icmp_seq=2 Destination unreachable: Address unreachable
From 2001:470:7950:10::100 icmp_seq=3 Destination unreachable: Address unreachable
From 2001:470:7950:10::100 icmp_seq=4 Destination unreachable: Address unreachable
^C
--- www.google.com ping statistics ---
4 packets transmitted, 0 received, +4 errors, 100% packet loss, time 2999ms

$ ping6 -n gateway
PING gateway(2001:470:7950:10::1) 56 data bytes
From 2001:470:7950:10::100 icmp_seq=1 Destination unreachable: Address unreachable
From 2001:470:7950:10::100 icmp_seq=2 Destination unreachable: Address unreachable
From 2001:470:7950:10::100 icmp_seq=3 Destination unreachable: Address unreachable
From 2001:470:7950:10::100 icmp_seq=4 Destination unreachable: Address unreachable
^C
--- gateway ping statistics ---
4 packets transmitted, 0 received, +4 errors, 100% packet loss, time 2999ms

This is a tcpdump while the ping was running:

# tcpdump -n -i br-lan icmp6                                                                                                                                                                        
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on br-lan, link-type EN10MB (Ethernet), capture size 262144 bytes
15:41:54.990240 IP6 2001:470:7950:10::100 > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has 2001:470:7950:10::1, length 32
15:41:55.992056 IP6 2001:470:7950:10::100 > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has 2001:470:7950:10::1, length 32
15:41:56.994060 IP6 2001:470:7950:10::100 > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has 2001:470:7950:10::1, length 32
15:41:57.643074 IP6 fe80::5054:ff:fee1:2f75 > 2001:470:7950:10::100: ICMP6, neighbor solicitation, who has 2001:470:7950:10::100, length 32
15:41:57.643148 IP6 2001:470:7950:10::100 > fe80::5054:ff:fee1:2f75: ICMP6, neighbor advertisement, tgt is 2001:470:7950:10::100, length 24
15:41:58.991235 IP6 2001:470:7950:10::100 > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has 2001:470:7950:10::1, length 32
15:41:59.992058 IP6 2001:470:7950:10::100 > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has 2001:470:7950:10::1, length 32
15:42:00.994060 IP6 2001:470:7950:10::100 > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has 2001:470:7950:10::1, length 32
15:42:02.660074 IP6 fe80::108f:1ae:a4ba:a348 > fe80::5054:ff:fee1:2f75: ICMP6, neighbor solicitation, who has fe80::5054:ff:fee1:2f75, length 32
15:42:02.660497 IP6 fe80::5054:ff:fee1:2f75 > fe80::108f:1ae:a4ba:a348: ICMP6, neighbor advertisement, tgt is fe80::5054:ff:fee1:2f75, length 24
15:42:02.992244 IP6 2001:470:7950:10::100 > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has 2001:470:7950:10::1, length 32
15:42:03.994060 IP6 2001:470:7950:10::100 > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has 2001:470:7950:10::1, length 32
^C
12 packets captured
12 packets received by filter
0 packets dropped by kernel

Thank you.