HostHatch: Private Networking and Broken IPv6

Thanks to brueggus on LowEndTalk for pointing this out and giving the solution.

If you have private networking enabled on a HostHatch VPS and your IPv6 connectivity is broken, it might be because of the lack of isolation between customers. The result is that someone can send IPv6 router advertisements via the private network and cause issues.

The fix relies on the fact that you have IPv6 manually configured on your VPS to access the public internet over IPv6, so make sure you have that as well.

1. Add net.ipv6.conf.eth1.accept_ra=0 to /etc/sysctl.conf
   • Make sure that eth1 matches the interface for your private network. Check using ip a and see what interface the 10.0.0.0/8 address on your VPS uses.
     • Typically eth1 = private network, while eth0 = public network. Though you might have something like enp0s3 or similar.
   • echo 'net.ipv6.conf.eth1.accept_ra=0' >> /etc/sysctl.conf
2. Run sysctl -p to apply the changes to /etc/sysctl.conf
3. Test IPv6 connectivity using something like curl: curl -6 -v https://icanhazip.com/