• radvd 1.9 using fe80::1 as gateway address

    From Marc Haber@21:1/5 to All on Sat Dec 12 19:20:02 2015

    radvd 1.9 in jessie behaves annoyingly different from what radvd 1.8
    in wheezy used to do.

    I commonly configure fe80::1 as a manually configured IPv6 address on
    inward pointing router interfaces that might be used as default
    gateway towards the Internet. This makes it easy to set a default
    route in case one needs to set one manually. I regularly run radvd on
    such interfaces as well, and I do believe that this is a rather common
    setup on IPv6 enabled routers.

    The kernel automatically auto-configures a link local EUI-64 address
    on the interface in addition, resulting in:

    |[1/500]mh@barrida:~$ ip -6 addr show dev int182
    |10: int182@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000 | inet6 2a01:238:4071:3282::a3:100/64 scope global
    | valid_lft forever preferred_lft forever
    | inet6 fe80::1/64 scope link
    | valid_lft forever preferred_lft forever
    | inet6 fe80::7c79:61ff:fe31:5528/64 scope link
    | valid_lft forever preferred_lft forever

    Radvd 1.9.1 in jessie in this case uses fe80::1/64 as a gateway
    address in its Router Announcements. Same with Radvd 2.1 on sid.

    Radvd 1.8 in wheezy advertises the gateway to be
    fe80::7c79:61ff:fe31:5528/64, using the link local EUI-64 address.

    Unfortunately, a SLAAC client running a recent Linux won't take
    fe80::1 for a gateway address if it has fe80::1 configured on a
    different interface itself, as it is commonly the case for VM hosts
    routing IP towards its VMs. Those hosts will silently ignore the
    gateway address, rendering them defaultgatewayless.

    Was that an intended change in radvd? Is there any way to get the old
    behavior back?


    -- ----------------------------------------------------------------------------- Marc Haber | "I don't trust Computers. They | Mailadresse im Header Leimen, Germany | lose things." Winona Ryder | Fon: *49 6224 1600402 Nordisch by Nature | How to make an American Quilt | Fax: *49 6224 1600421

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