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Category Archives: IPv6

Configuring an IPv6 Address in GCP

Posted on November 22, 2018 by cbroccoli

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Once I had a working Instance Group I was able to then able to begin configuring the load balancer. IPv6 load balancing is described in this article. Essentially they are configuring a reverse proxy which terminates the IPv6 connection and builds a new IPv4 connection to the backend server.

The first step is to select a load balancer and in this case I selected an HTTP(S) load balancer. Once selected you need to configure the Backend, the Path Rules/URL Map and the Frontend as shown in the following diagram:

The Back End maps the load balancer to the instance group. I chose to disable autoscaling and limit the total number of hosts to 1. If you have a stateless server you can allow the load balancer to autoscale the service as needed based on load. Since my LAMP server has a local MySQL database this would not work.

For the Path Rules I added the name and pointed it to the main page for WordPress. You need to enter a name for the server since GCP does not take IPv6 IP addresses (IPv4 works fine). Without this rule the load balancer will not know where to route the incoming http packet.

For the Front End I added both IPv4 and IPv6 addresses for testing purposes, in case I needed IPv4 access.

Once that was complete I could begin testing. Luckily for me my ISP has already rolled out IPv6 to my house so I already had IPv6 access. For the client configuration, I added a new static entry in my hosts file to allow me to use a name to access the server. I only configured the IPv6 address and to make sure IPv4 was not used at any point in the connection, I removed IPv4 from my network adapter. Once this was done, I was able to use my web browser and access the WordPress host.

In Wireshark you can see the entire IPv6 connection which shows clearly that the configuration works.

IP Addresses in WordPress

Posted on November 19, 2018 by cbroccoli

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Since I was just working in a test instance of GCP, I didn’t have DNS running for the server and was using IP addresses for everything. This posed a problem with WordPress since it stored the IP addresses from the original installation server in the configuration. Naturally when I booted the new instance group using the disk image created from the original WordPress server, GCP assigned a new IP address to the server and the site no longer worked.

The fix is to update the database to reflect the new public IP address via ssh. After some searching in the WordPress blogs, I was able to find the following changes which seem to have done the trick. If you don’t do this step, then whenever you access the site it will attempt to access the old IP address and fail.

chris@instance-group-wordpress-lmfd:$ sudo mysql -u root -p
password:##########
mysql> use wordpress;
mysql> show tables;
+-----------------------+
| Tables_in_wordpress   |
+-----------------------+
| wp_commentmeta        |
| wp_comments           |
| wp_links              |
| wp_options            |
| wp_postmeta           |
| wp_posts              |
| wp_term_relationships |
| wp_term_taxonomy      |
| wp_termmeta           |
| wp_terms              |
| wp_usermeta           |
| wp_users              |
+-----------------------+
mysql> UPDATE wp_options SET option_value = "http://NEW_IP_ADDRESS" 
WHERE option_value = 'http://OLD_IP_ADDRESS';
mysql> exit;

I originally did this with IPv4 addresses. However, since my goal was to get the site running with IPv6, I first changed the addresses to IPv6 via the console to test if a raw IP address would work, then I changed both addresses to the domain name, which would be the preferred option when working with a production site. In both cases WordPress accepted the changes and the site worked as expected. Below is a screenshot of the console with a mix of IPv6 and domain name configured.

IPv6 in GCP

Posted on November 18, 2018 by cbroccoli

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I recently attended training on Google Cloud Platform to become a Google Certified Professional Cloud Architect. During the training I learned that GCP does not support IPv6 natively on Compute Engine instances. I have been using IPv6 at home for years and I know that Google has been supporting IPv6 on its search engine for the same amount of time, so the lack of support was disappointing. The solution for IPv6 on GCP is to implement a public facing load balancer which will expose an IPv6 address to the Internet and NAT that address to the internal RFC1918 private IPv4 address. Although this is a valid short term option when migrating to IPv6, one of the great benefits of implementing IPv6 is to eradicate NAT from the world, so hopefully this situation is only temporary and in the future native end to end IPv6 will be supported on GCP. In the mean time, since we need to live with this solution, I thought it would be worth while to test it and see how it works.

So that I was not just doing a basic protocol test, I decided to use WordPress as the target application. This would allow for more robust testing of the solution and had the advantage of allowing me to practice what I had learned in training on something more than just a basic Apache server. Another advantage is that this test would allow me to evaluate if I should move this Blog to GCP and make it IPv6 capable, since at the moment it is not.

With this in mind, I will publish a series of posts covering the steps I am following to get WordPress running on IPv6. Not all of the steps are directly related to IPv6, but are necessary when setting up a load balanced service in GCP. Along the way I will share experiences and tips which might prove helpful for future installations.

In the first step, I will setup a reusable Compute Engine image with a LAMP stack and WordPress. Using the WordPress Image I will then setup the load balancer with an IPv6 address. Finally, I will test using a native IPv6 host. The diagram below shows an overview of the design: