RHEL instance not getting a default IPv6 route

I had to change IPV6_ADDR_GEN_MODE from stable_privacy to eui64 and set IPV6_PRIVACY=no to get my SLAAC address, but I'm still not getting a default route on the v6 stack:

[joliver@leaf ~]$ ip -6 route sh
::1 dev lo proto kernel metric 256 pref medium
fe80::/64 dev enp0s3 proto kernel metric 1024 pref medium
default via fe80::1 dev enp0s3 proto ra metric 100 pref medium

I'm fissling with tcpdump to see if I can grab the router advertisements and see if I can discover my gateway that way, but I'd prefer to fix this so SLAAC "just works".

1 Reply

The easiest way to configure your SLAAC address automatically would be to deploy servers with Network Helper on. I've tested this on Centos 8 Stream as an example, and I was able to use my SLAAC address right away both with and without Network Helper, but some distributions may work differently. If a distro is supported, Network Helper is usually the best option for this.

If you're using a supported distro, you can change your global settings so that all new instances are deployed with this feature on.

If Network Helper doesn't work for you, you may have to also change one setting that you didn't mention, based on our guide to manual network configuration using Network Manager. In addition to the changes you mentioned, that also suggests IPV6INIT to yes in /etc/sysconfig/network-scripts/ifcfg-eth0.:


In CentOS Stream 8, all the configurations you've mentioned seemed to be the default whether I had Network Helper on or not. Depending on the distribution you're using, you may or may not see the same configurations.

If Network Helper isn't an option for you for some reason, it may be possible to find configurations that work for you on your current server. You may be able to automatically configure your IPs using these SLAAC configurations for IPv6 and DHCP for IPv4, and then make a Golden Image to use to deploy future servers so that things work the way you want them to at the time of deployment.


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