O pacote inacessível de destino do ICMPv6 ajudou a identificar o problema como um problema de firewall.
Adicionando uma regra para encaminhar pacotes IPv6 em br0 corrigiu o problema:
ip6tables -I FORWARD 6 -i br0 -s 2001:db8:1600:80bf::/64 -j ACCEPT
Eu tenho uma máquina virtual Windows Server 2008 R2 SP1 recém-instalada que é completamente incapaz de acessar qualquer página da Web IPv6, apesar de aparentemente ter a devida conectividade IPv6. Além disso, outras VMs do Linux também não podem acessar os sites IPv6.
Essa configuração funcionou anteriormente, com conectividade IPv6 completa nas máquinas virtuais, e parou de funcionar sem um motivo óbvio.
Todas as minhas VMs são conectadas à Ethernet física e recebem anúncios do radvd na máquina host. O IPv6 funciona corretamente na máquina host, que também é o roteador IPv6. O Wireshark mostra que a máquina host está enviando de volta um destino ICMPv6 inacessível (administrativamente proibido) depois de receber o pacote HTTP SYN.
O Internet Explorer informa que não é possível exibir a página da Web, e o Google Chrome só diz Ops! O Chrome não pôde se conectar à página da Web, sem um número de erro.
Eu sou capaz de fazer ping no gateway local e nos endereços IPv6 do Google e fazer pesquisas de DNS IPv6.
PS C:\Users\Administrator> ping -6 fe80::6e62:6dff:fed1:dfad
Pinging fe80::6e62:6dff:fed1:dfad with 32 bytes of data:
Reply from fe80::6e62:6dff:fed1:dfad: time<1ms
Reply from fe80::6e62:6dff:fed1:dfad: time<1ms
Reply from fe80::6e62:6dff:fed1:dfad: time<1ms
Reply from fe80::6e62:6dff:fed1:dfad: time<1ms
Ping statistics for fe80::6e62:6dff:fed1:dfad:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms
PS C:\Users\Administrator> ping -6 www.google.com
Pinging www.l.google.com [2001:4860:800a::67] with 32 bytes of data:
Reply from 2001:4860:800a::67: time=43ms
Reply from 2001:4860:800a::67: time=42ms
Reply from 2001:4860:800a::67: time=46ms
Reply from 2001:4860:800a::67: time=42ms
Ping statistics for 2001:4860:800a::67:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 42ms, Maximum = 46ms, Average = 43ms
A configuração da minha máquina virtual é assim:
PS C:\Users\Administrator> ipconfig /all
Windows IP Configuration
Host Name . . . . . . . . . . . . : WIN-CRLO5NIQB72
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : local
Ethernet adapter Local Area Connection 2:
Connection-specific DNS Suffix . : local
Description . . . . . . . . . . . : Red Hat VirtIO Ethernet Adapter
Physical Address. . . . . . . . . : 52-54-00-DD-DF-3E
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IPv6 Address. . . . . . . . . . . : 2001:db8:1600:80bf:5054:ff:fedd:df3e(Preferred)
Link-local IPv6 Address . . . . . : fe80::5054:ff:fedd:df3e%13(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.12.146(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Monday, July 09, 2012 1:59:42 PM
Lease Expires . . . . . . . . . . : Tuesday, July 10, 2012 1:59:42 PM
Default Gateway . . . . . . . . . : fe80::6e62:6dff:fed1:dfad%13
192.168.12.1
DHCP Server . . . . . . . . . . . : 192.168.12.1
DNS Servers . . . . . . . . . . . : 2001:4860:4860::8888
2001:4860:4860::8844
192.168.12.1
NetBIOS over Tcpip. . . . . . . . : Enabled
Tunnel adapter isatap.local:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . : local
Description . . . . . . . . . . . : Microsoft ISATAP Adapter
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Tunnel adapter Teredo Tunneling Pseudo-Interface:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft Teredo Tunneling Adapter
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
IPv6 Address. . . . . . . . . . . : 2001:0:4137:9e76:10d1:317d:3f57:f36d(Preferred)
Link-local IPv6 Address . . . . . : fe80::10d1:317d:3f57:f36d%12(Preferred)
Default Gateway . . . . . . . . . :
NetBIOS over Tcpip. . . . . . . . : Disabled
PS C:\Users\Administrator> netsh interface ipv6 show route
Publish Type Met Prefix Idx Gateway/Interface Name
------- -------- --- ------------------------ --- ------------------------
No Manual 256 ::/0 13 fe80::6e62:6dff:fed1:dfad
No Manual 256 ::1/128 1 Loopback Pseudo-Interface 1
No Manual 8 2001::/32 12 Teredo Tunneling Pseudo-Interface
No Manual 256 2001:0:4137:9e76:10d1:317d:3f57:f36d/128 12 Teredo Tunneling Pseudo-Interface
No Manual 8 2001:db8:1600:80bf::/64 13 Local Area Connection 2
No Manual 256 2001:db8:1600:80bf:5054:ff:fedd:df3e/128 13 Local Area Connection 2
No Manual 256 fe80::/64 13 Local Area Connection 2
No Manual 256 fe80::/64 12 Teredo Tunneling Pseudo-Interface
No Manual 256 fe80::5efe:192.168.12.146/128 11 isatap.local
No Manual 256 fe80::10d1:317d:3f57:f36d/128 12 Teredo Tunneling Pseudo-Interface
No Manual 256 fe80::5054:ff:fedd:df3e/128 13 Local Area Connection 2
No Manual 256 ff00::/8 1 Loopback Pseudo-Interface 1
No Manual 256 ff00::/8 13 Local Area Connection 2
No Manual 256 ff00::/8 12 Teredo Tunneling Pseudo-Interface
PS C:\Users\Administrator> netsh interface ipv6 show prefixpolicies
Querying active state...
Precedence Label Prefix
---------- ----- --------------------------------
50 0 ::1/128
40 1 ::/0
30 2 2002::/16
20 3 ::/96
10 4 ::ffff:0:0/96
5 5 2001::/32
Até agora, na VM, tentei:
netsh interface ipv6 set global randomizeidentifiers=disabled
Nenhuma alteração.
Desabilitando o adaptador Teredo: sem alteração. E de alguma forma foi reativado.
Usando o Microsoft Fix-It para preferir o IPv6 ao IPv4 : nenhuma alteração.
Até agora, no host que experimentei:
Verificado pelo sysctl de encaminhamento de IPv6:
net.ipv6.conf.all.forwarding = 1
net.ipv6.conf.br0.forwarding = 1
net.ipv6.conf.default.forwarding = 1
net.ipv6.conf.em1.forwarding = 1
net.ipv6.conf.lo.forwarding = 1
net.ipv6.conf.sit0.forwarding = 1
net.ipv6.conf.sixxs.forwarding = 1
net.ipv6.conf.virbr0.forwarding = 1
net.ipv6.conf.virbr0-nic.forwarding = 1
net.ipv6.conf.vnet0.forwarding = 1
net.ipv6.conf.vnet1.forwarding = 1
net.ipv6.conf.vnet2.forwarding = 1
Radvd reiniciado: sem alteração.