The following article was contributed by Paul Heinlein, a systems administrator at Galois. Paul attended my full day IPv6 training course at USENIX LISA 2013 and just a couple of months later sent me a report of his successful deployment of IPv6. So I asked if he'd like to contribute an article on the topic.
It's great to hear of IPv6 success stories like this. (And of course, I'm glad folks are finding my courses useful). Significantly, his network is already seeing a very substantial amount of IPv6 traffic!
(A note: the version of iptables in Redhat Enterprise Linux6/CentOS 6 has fixed the stateful IPv6 inspection capability. We use it successfully at Penn).
You can find the slides from my IPv6 training course on my website.
An IPv6 Success Story
Galois is a software-engineering firm located in Portland, OR that specializes in the hard problems of computing trust and assurance.
One of our IT goals for 2014 is enabling IPv6 on all our current IPv4 subnets. I was pleased to see Shumon's full-day IPv6 tutorial on the LISA '13 schedule. I hoped he could fill the gaps in my limited experience with IPv6 and provide me the knowledge I'd need to configure our network hardware and applications.
Full-day technical tutorials can sometimes test my patience, but Shumon's presentation moved quickly while remaining clear. I came away from the day thinking that I had enough basic knowledge to plan and implement our IPv6 rollout.
Returning to Portland, I had to upgrade upgrade a couple core switches and apply to our ISP for a netblock prior to enabling it on our network, but once the hardware was in place, everything went reasonably well.
Shumon's overview had done exactly what I'd hoped it would: allow me to interpret the various bits of vendor-specific and application-specific documentation and assemble a reasonable roll-out plan.
Our DMZ and client networks are now fully IPv6 enabled. (Internal development networks will take a bit more time due to VPN-related complexity.)
Along the way, I learned a couple things Shumon didn't explicitly cover in his presentation.
First, make sure that reverse DNS pointers are in place for any mail server before enabling IPv6. gmail (among others) will reject messages from any mail server without reverse DNS pointers in place.
Second, the ip6tables that ships with RHEL/CentOS 5 has a limited ability to do stateful packet inspection. The generic rule allowing packets from established or related sessions does not work:
# this is broken in RHEL/CentOS 5 -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
(We've only got one CentOS 5 machine in our DMZ, so this issue hasn't impacted us in any major way.)
Third, it was a lot of fun! Nearly all our DMZ services (NTP, DNS, Jabber, e-mail, www, ssh, host-based firewalls) needed updated configurations, so I learned a bunch. The day after I did the initial rollout, one of our engineers came into the office, turned off IPv4 on his Mac, and tested what percentage of Google result links he could follow. (He thought about 5%, though he said the queries he chose probably resulted in a higher success rate than might be normal.)
Finally, I've been mildly surprised at the quantity of IPv6 packets traversing our border firewall. Over the past week, IPv6 has comprised 38% of overall inbound traffic and 11% of outbound. The numbers are similar when scoped to the past month.
I'd like to express my thanks to Shumon for the talk and the LISA organizers for putting it on the schedule!
-- Paul Heinlein firstname.lastname@example.org