IPv6 routing stops when openvpn devices is enabled (solved)

Installing and Using OpenWrt
1

I have an openwrt behind another router and when opening sites like ifconfig.io they report an IPv6 address.

When I enable one of my openvpn interfaces (no routing, no firewall zone defined), my IPv6 routing stops and when I open ifconfig.io I get my IPv4 address.
When I disable the openvpn interface, it goes back to IPv6.

How can I prevent my IPv6 routing from getting disabled?

Here is the config for the openvpn device:

client
remote <server> 443
dev tunCGcr
proto udp
auth-user-pass /etc/openvpn/cyberghost_cr.auth

resolv-retry infinite
#redirect-gateway def1
pull-filter ignore "redirect-gateway"
persist-key
persist-tun
nobind
cipher AES-256-CBC
auth SHA256
ping 5
ping-exit 60
ping-timer-rem
explicit-exit-notify 2
script-security 2
remote-cert-tls server
route-delay 5
verb 4

ca /etc/openvpn/cyberghost_ca.crt
cert /etc/openvpn/cyberghost_cr_client.crt
key /etc/openvpn/cyberghost_cr_client.key
2

Maybe IPv6 default routes are added.
Your log should show that, check with logread -e openvpn

To stop setting default route for IPv6 you need to add:

pull-filter ignore "redirect-gateway ipv6"

I have seen providers settings default routes by pushing ::/2 routes in that case you should use:

pull-filter ignore "route-ipv6 0000::/2"
pull-filter ignore "route-ipv6 4000::/2"
pull-filter ignore "route-ipv6 8000::/2"
pull-filter ignore "route-ipv6 C000::/2"

If you want to disable IPv6 altogether:

pull-filter ignore "route-ipv6"
pull-filter ignore "ifconfig-ipv6"
block-ipv6
pull-filter ignore "redirect-gateway ipv6"

If that does not help we need to see your configs and logs

4

I have disabled IPv6 as given in your example above and, yes, that cures it.
The route that is added without that is:

2000::/3 dev tunCGus metric 1024 pref medium

and that seems to ruin the routing.
Thanks very much!

1 Like
5

Great to hear it is solved.
I will add that to my list, but indeed 2000::/3 also mimics a default route.
Which provider is using that?