can't make ipv4 dhcp and ipv6 static both exist

[Lennart Sorensen]

On Wed, Oct 30, 2013 at 09:56:14PM -0400, Neil Watson wrote:
> Greetings,
> 
> On a debian laptop I have the following interfaces file. For some reason the
> IPV6 address will not set. Why?
> 
> auto lo br0
> iface lo inet loopback
> iface lo inet6 loopback
> 
> allow-hotplug br0 wlan0
> 
> iface br0 inet dhcp
>         bridge_ports eth0
>         bridge_stop off
>         bridge_fd 0
>         bridge_maxwait 0
> 
> iface br0 inet6 static
>         address 2001:470:1d:a2f::4
>         netmask 64
>         gateway 2001:470:1d:a2f::1
> 
> 
> root at neptune:/etc/network# ifconfig
> br0       Link encap:Ethernet  HWaddr f0:de:f1:d8:0d:87
> inet addr:172.16.100.19  Bcast:172.16.100.255  Mask:255.255.255.0
>           inet6 addr: fe80::f2de:f1ff:fed8:d87/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:1965 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:1647 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0
>           RX bytes:1511472 (1.4 MiB)  TX bytes:217730 (212.6 KiB)
> 
> eth0      Link encap:Ethernet  HWaddr f0:de:f1:d8:0d:87           UP
> BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:7437 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:4924 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:7126724 (6.7 MiB)  TX bytes:650467 (635.2 KiB)
>           Interrupt:20 Memory:f2500000-f2520000
> 
> lo        Link encap:Local Loopback           inet addr:127.0.0.1
> Mask:255.0.0.0
>           inet6 addr: ::1/128 Scope:Host
>           UP LOOPBACK RUNNING  MTU:65536  Metric:1
>           RX packets:10 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0
>           RX bytes:1380 (1.3 KiB)  TX bytes:1380 (1.3 KiB)

Very likely everytime the dhcp client for IPv4 gets an addres, it wipes
all the addresses on the interface.

I wonder if using network-manager to handle things instead would work
better.  I haven't tried doing both IPv4 and IPv6 at the same time that
I recall with it (although maybe I did, but they would both havre been
static in that case).

Also why are you using ifconfig?  ip addr and ip -6 addr are the modern
ways to check IP settings.  ifconfig doesn't generally work well with
multiple IPs on an interface, and is just obsolete (and also uses /proc
parsing rather than netlink).

-- 
Len Sorensen
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