Stephen Spector suggested these questions may be best answered by the dev email
My team and I have been working diligently since early this year working on
automation and deployment of Xen for a new VPS service at DynDNS. Along the
way, we decided to have IPv6 as one of our features, and had to make a handful
of changes to the Xen network scripts to successfully and safely do so in a VPS
While our priorities have first and foremost getting our Spring Server VPS
service out the door (which as of a few weeks ago, it is!), now I'd like to see
if the community could benefit from this work.
a) Have people already solved and dealt with IPv6 in Xen successfully (i.e., is
it a non-issue at this point)? If not, I'd be happy to submit the changes and a
guide to making it work and work well.
Along the way, we also ran into some issues where domUs were able to:
1) "steal" IP addresses through IP aliasing (e.g., domU has 188.8.131.52, and domU
root does "ifconfig eth0:0 184.108.40.206/32" in Linux, and now has two working IPs),
2) and more importantly, were able to impact the network connectivity of
another domU by aliasing or assigning its in-use IP address,
3) and MOST importantly, were able to impact the network connectivity for all
domUs on a subnet by aliasing a gateway IP address (e.g., in Linux "ifconfig
220.127.116.11" for a typical /24 subnet).
4) Also, sending out invalid or poisoned ARP packets from one domU were able to
introduce network connectivity problems for other domUs.
We were able to make a handful of changes to the Xen scripts to resolve these
issues as well for safe and secure operation (especially for a VPS environment,
where individual owners of domUs are likely unrelated to each other).
b) As above, have folks already addressed these issues for stealing IPs/ARP
poisoning? Have they just not encountered them yet? Would it be useful to
submit these modifications for review by the community?
We're more than happy to help, just don't want to duplicate work or step on
anyone's toes for work they already have in progress.
Cory von Wallenstein
Spring Server Engineer
Dynamic Network Services
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