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  • IPv6-only with SLAAC doesn't update resolv.conf

    From Alexander Koeppe@21:1/5 to All on Thu Sep 27 21:00:02 2018
    Hello list,

    I'd like to make some experiences what would happen if tomorrow I'd wake
    up in a IPv6-only world.

    Therefore I've updated my /etc/network/interfaces file so to have only a
    "iface wlan0 inet6 auto" statement w/o a "iface wlan0 inet dhcp" statement.

    The observation I've made was that interface addressing works as
    expected, but name resolution doesn't work, since /etc/resolv.conf still
    points to the IPv4 address set by the DHCP config before.

    I've also installed and started resolvconf package but this didn't help
    either.
    I've also read the Kernel IPv6 networking documentation (suspected a /proc/sys/net flag) but found no variable that would influence this
    behaviour.

    What would be Linux' solution to such a typical setup where no DHCPv6
    server is around, like in any consumer environment?

    Is there a gap of thinking, either on my side or on Linux's developers side?

    Regards
    - Alex

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jens Link@21:1/5 to Alexander Koeppe on Thu Sep 27 21:20:01 2018
    Alexander Koeppe <[email protected]> writes:

    Hello list,

    I'd like to make some experiences what would happen if tomorrow I'd wake
    up in a IPv6-only world.

    Therefore I've updated my /etc/network/interfaces file so to have only a "iface wlan0 inet6 auto" statement w/o a "iface wlan0 inet dhcp"
    statement.

    The observation I've made was that interface addressing works as
    expected, but name resolution doesn't work, since /etc/resolv.conf still points to the IPv4 address set by the DHCP config before.

    So with out dhcpv6 client you can use "IPv6 Router Advertisement Options
    for DNS Configuration" (RFC 5006^W6106^W8106)

    To use this on Linux you need to install the rdnssd client. radvd also
    supports this option if you are using Linux as router.

    Note: This is not supported on several older model routers so you can
    either change the router, use dual-stack or DHCPv6 (which wont work for
    Android devices).

    Jens
    --
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    | Foelderichstr. 40 | 13595 Berlin, Germany | +49-151-18721264 |
    | http://blog.quux.de | jabber: [email protected] | --------------- | ----------------------------------------------------------------------------

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Alexander Koeppe@21:1/5 to All on Thu Sep 27 23:00:02 2018
    Am 27.09.2018 um 21:02 schrieb Jens Link:

    So with out dhcpv6 client you can use "IPv6 Router Advertisement Options
    for DNS Configuration" (RFC 5006^W6106^W8106)


    I've checked of course that the option is set in the router
    advertisement in a packet capture.

    Let me have a look at the rdnssd client.

    Thanks
    - Alex

    P.S.
    This box is just a netbook. Not running as a router.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Pascal Hambourg@21:1/5 to All on Thu Sep 27 23:20:02 2018
    Le 27/09/2018 à 20:49, Alexander Koeppe a écrit :

    I've also installed and started resolvconf package but this didn't help either.

    Of course not. resolvconf does not create DNS, it just manages DNS
    sources. It is useful if you have several DNS sources conflicting with
    each other such as DHCP, SLAAC...

    What would be Linux' solution to such a typical setup where no DHCPv6
    server is around, like in any consumer environment?

    Install rdnssd.

    Is there a gap of thinking, either on my side or on Linux's developers side?

    The kernel alone receives IPv6 router advertisements (RAs) but will not
    modify any file such as resolv.conf. So a userland process must do it.
    This is the purpose of rdnssd.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Alexander Koeppe@21:1/5 to All on Mon Oct 1 00:20:01 2018
    Am 27.09.2018 um 23:14 schrieb Pascal Hambourg:

    The kernel alone receives IPv6 router advertisements (RAs) but will not modify any file such as resolv.conf. So a userland process must do it.
    This is the purpose of rdnssd.



    Thanks for the explanation.

    rdnssd works out perfectly which Jens Link had already suggested in a
    previous message.

    Thank you both.


    - Alex

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jens Link@21:1/5 to Alexander Koeppe on Mon Oct 1 11:20:01 2018
    Alexander Koeppe <[email protected]> writes:

    This box is just a netbook. Not running as a router.

    But there are people using other things as Linux boxes as router. I
    guess Cisco Cat 6500 or 4500 are still quite common and I know that they
    wont support RFC5006/6106/8106 (at least in older versions of the
    supervisor engine).

    Jens
    --
    ----------------------------------------------------------------------------
    | Foelderichstr. 40 | 13595 Berlin, Germany | +49-151-18721264 |
    | http://blog.quux.de | jabber: [email protected] | --------------- | ----------------------------------------------------------------------------

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)