IPv6 on AWS EC2 - Debian 11

[Squiggly9461]

I just noticed when I install either wireguard or OpenVPN created by angristan the IPv6 is no longer reachable.

IPv6 has been properly configured on VPC and is reachable on the internet. I have a Vultr VPS as well and its working fine.

Any idea or are there any changes should we made for AWS EC2 instances? This also affects AWS Lightsail.

[angristan]

Can you precise:

the IPv6 is no longer reachable

Which IPv6, and from where?

[MSe1969]

Wireguard requires IP-Forwarding, which is therefore enabled by the 'wireguard-install' script.

Your issue is indeed a VPS-provider specific issue:
On Debian (Ubuntu seems different here), enabling ip6 forwarding disables the so-called "router advertisement", you can see that in the comments section of /etc/sysctl.conf:

# Uncomment the next line to enable packet forwarding for IPv6
#  Enabling this option disables Stateless Address Autoconfiguration
#  based on Router Advertisements for this host
#net.ipv6.conf.all.forwarding=1

So if your provider uses router advertisement as part of the IPv6 autoconfiguration, you get - at least on a Debian system - an issue with IPv6, when you enable IPv6 forwarding.

On an AWS Lightsail instance with Debian, the problem is solved as follows:
First, get the interface name (e.g. ip route show default) - it returns something like "default via [ip-address] dev [interface] [further stuff], so you take the expression after "dev" - should normally be eth0 on a Lightsail instance.

Next add the entry "net.ipv6.conf.eth0.accept_ra=2" into /etc/sysctl.conf (adapt accordingly with the real interface used) :

# Uncomment the next line to enable packet forwarding for IPv6
#  Enabling this option disables Stateless Address Autoconfiguration
#  based on Router Advertisements for this host
net.ipv6.conf.all.forwarding=1
net.ipv6.conf.eth0.accept_ra=2

(If your IPv6 is already screwed, reboot the instance afterwards sudo shutdown -r)

[nameup2]

Thanks bro,you solved my problem!this problem has troubled me for a month