IPv6 addresses

[Paul Makepeace]

On Sun, Mar 11, 2012 at 15:43, Chris Dennis <cgdennis at btinternet.com> wrote:
> Hello folks
>
> I'm hacking together a quick script to parse the output from the 'ip'
> command on Linux, e.g.
>
> $ ip a s
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
>    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>    inet 127.0.0.1/8 scope host lo
>    inet6 ::1/128 scope host
>       valid_lft forever preferred_lft forever
> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen
> 1000
>    link/ether 00:19:b9:06:4c:86 brd ff:ff:ff:ff:ff:ff
>    inet 192.168.1.7/24 brd 192.168.1.255 scope global eth0
>    inet6 2001:dead:beef:cafe::1/64 scope global dynamic
>       valid_lft 86147sec preferred_lft 14147sec
>    inet6 fe80::1/64 scope link
>       valid_lft forever preferred_lft forever
>
> -- which is straightforward.  But then I need to process the IPv6 addresses
> to be able to extract subnet prefixes etc.

$ /sbin/ifconfig  | perl -MRegexp::IPv6=\$IPv6_re -lne
'/(?:($IPv6_re)(\/\d+))/ and print "net $1 size $2"'
net fe80::fcff:ff:fe00:5272 size /64
net ::1 size /128

HTH,
Paul

>
> CPAN has so many IPv6-mangling modules that I don't know which to choose, or
> which will emerge as the best/most stable etc. in the future.  Certainly
> some of the ones I've looked at are badly written or badly documented or
> just plain broken.
>
> Any recommendations?
>
> cheers
>
> Chris
> --
> Chris Dennis                                  cgdennis at btinternet.com
> Fordingbridge, Hampshire, UK