I’ve run across this peculiar problem. I was trying to set up IPv6 on a Centos 6 machine. I thought that it would be a simple task – a couple of minutes at most – as I had done that on other Centos 6 machines before. But I was wrong.<\/p>\n
My initial configuration steps were:<\/p>\n
# cat \/etc\/sysconfig\/network | grep IPV6\r\nNETWORKING_IPV6=yes\r\n<\/pre>\n# cat \/etc\/sysconfig\/network-scripts\/ifcfg-eth0\r\nDEVICE=eth0\r\nTYPE=Ethernet\r\nONBOOT=yes\r\nNM_CONTROLLED=no\r\nBOOTPROTO=none\r\n...\r\nIPV6INIT=yes\r\nIPV6_AUTOCONF=no\r\nIPV6_DEFROUTE=yes\r\nNAME=\"System eth0\"\r\nIPV6ADDR=2a01:xxxx:xxxx:xxxx::1\/64\r\nIPV6_DEFAULTGW=2a01:xxxx:xxxx:yyyy::1\r\n<\/pre>\nTake note of the two (obfuscated) IP addresses, the machine IP address\u00a02a01:xxxx:xxxx:xxxx::1 is in a different subnet than the IP address 2a01:xxxx:xxxx:yyyy::1 of the default gateway given to me by the ISP.<\/p>\n
On other machines I had configured in the past, IPV6_DEFAULTGW was 2a01:xxxx:xxxx::1,<\/em>\u00a0in other words – my own machine’s IP address 2a01:xxxx:xxxx:xxxx::1<\/em> was in a subnet that was a part of the bigger\u00a02a01:xxxx:xxxx::<\/em> subnet in which the ISP’s gateway machine was located. In those cases, IPv6 worked without any problems when I used the above mentioned simple configuration. But here, it didn’t work, I was getting the following warning and wasn’t able to connect\/ping anywhere:<\/p>\n
WARN : [ipv6_add_route] 'No route to host' adding route '::\/0' via gateway '2a01:xxxx:xxxx:yyyy::1'\r\n<\/pre>\nI tried specifying the interface, like this:<\/p>\n
IPV6_DEFAULTGW=2a01:xxxx:xxxx:yyyy::1%eth0\r\n<\/pre>\nbut that didn’t help either.<\/p>\n
Eventually, I got an advice from a friend who’s far more IPv6 savvy than I am. I had thought that it was not possible to have default gateway in a completely different subnet and that this was the reason why I was running into this problem, but I was told that IPv6, unlike IPv4, did actually allow for a gateway to be in a different subnet, but in those cases, addtional network script has to be configured like this:<\/p>\n
# cat \/etc\/sysconfig\/network-scripts\/route6-eth0 \r\n2a01:xxxx:xxxx:yyyy::1 dev eth0\r\ndefault via 2a01:xxxx:xxxx:yyyy::1\r\n<\/pre>\nHaving set the gateway this way, I had to remove it from the interface configuration file, of course:<\/p>\n
# cat \/etc\/sysconfig\/network-scripts\/ifcfg-eth0\r\n...\r\nIPV6ADDR=2a01:xxxx:xxxx:xxxx::1\/64\r\n#IPV6_DEFAULTGW=2a01:xxxx:xxxx:yyyy::1\r\n<\/pre>\nAfter restarting network, this machine was finally IPv6 ready.<\/p>\n","protected":false},"excerpt":{"rendered":"
I’ve run across this peculiar problem. I was trying to set up IPv6 on a Centos 6 machine. I thought that it would be a simple task – a couple of minutes at most – as I had done that …<\/p>\n