Hi listers I have activated an IPv6 router in the local network. Every host has, as expectect, grabbed the prefix and constructed its own Link local, Site local (if requested), and Global addresses. Problem is: from when on is IPv6 adress information available for a certain interface?
I have a laptop which I normally use via Ethernet (interface eth0). But at times, I use it via wlan0. As I have installed a test enironment for two Web applications on the laptop, I need to dynamically change the DNS for these applications, depending on which IP address (IPv4 as well as IPv6) the laptop is on. I had developped a script, which automatically changes DNS for the laptop, when I restart the network on the laptop (/etc/init.d/network restart). The IPv4 address for the laptop comes in via DHCP, IPv6 address comes in via neighbor and router solicitation. After DHCP and neigbor/router solicitation, the script to update the dynamic DNS asks for the actual IPv4 address, which is readily available at that point in time. Then it asks also for the IPv6 address, and gets the empty string. A snippet of the output of this DNS update script when used with wlan0 follows:
... Shutting down loopback interface: [ OK ] Bringing up loopback interface: [ OK ] Bringing up interface eth0: Determining IP information for eth0... failed; no link present. Check cable? [FAILED] Bringing up interface wlan0: Determining IP information for wlan0...++ ip -o -f inet6 addr show dev wlan0 scope site + ad= ++ echo ++ /usr/local/scripts/extract-field.pl '' 4 + ax= ++ echo ++ cut -d/ -f1 + ay= + echo server ns.mydomain.com update delete dick.dyn.lan A update delete dick.dyn.lan AAAA update add dick.dyn.lan 86400 A 192.168.97.20 update add dick.dyn.lan 86400 AAAA update delete bg.dyn.lan CNAME update add bg.dyn.lan 86400 CNAME dick.dyn.lan update delete auth.dyn.lan CNAME update add auth.dyn.lan 86400 CNAME dick.dyn.lan send Creating key... ...
As you can see from the DNS update command list, the IPv4 address is present, whereas the IPv6 address is empty. The IPv6 address is asked for via the command ip -o -f inet6 addr show dev wlan0 scope site which returns an empty string.
When, after this procedure, I recall the DNS update script manually, everything works fine including the IPv6 address.
Has anybody had similar troubles when asking for IPv6 address data from an interface?
Thanks in advance for any hint.
suomi
On Mon, Mar 15, 2010 at 02:20:55PM +0100, fedora wrote:
As you can see from the DNS update command list, the IPv4 address is present, whereas the IPv6 address is empty. The IPv6 address is asked for via the command ip -o -f inet6 addr show dev wlan0 scope site which returns an empty string.
See MinRtrAdvInterval and MaxRtrAdvInterval in your /etc/radvd.conf on your router that advertises the IPv6 prefix. Default is minimum 30 seconds, max 100 seconds, which in means you're slipping in to bring up the interface and set your DDNS between announcements.
Thanks, Matt
Thanks Matt that was it.
suomi
On 2010-03-15 14:33, Matt Domsch wrote:
On Mon, Mar 15, 2010 at 02:20:55PM +0100, fedora wrote:
As you can see from the DNS update command list, the IPv4 address is present, whereas the IPv6 address is empty. The IPv6 address is asked for via the command ip -o -f inet6 addr show dev wlan0 scope site which returns an empty string.
See MinRtrAdvInterval and MaxRtrAdvInterval in your /etc/radvd.conf on your router that advertises the IPv6 prefix. Default is minimum 30 seconds, max 100 seconds, which in means you're slipping in to bring up the interface and set your DDNS between announcements.
Thanks, Matt
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fedora -
Matt Domsch