Re: ipv6 accept_ra

[Anssi Saari <as@sci.fi>]

Lee <ler762@gmail.com> writes:

> I have a desktop and a laptop - neither one is picking up the ipv6
> network prefix from the router advertisement.  'ifconfig -a' on both
> show a single 'inet6 fe80::' line under each interface.

Well, how do you manage your network? Is there a checkbox to check or
uncheck somewhere? A firewall blocking the RAs?

For me IPv6 works without enabling anything specifically. On my
computers I mostly use systemd-networkd but I seem to have nothing
IPv6-related in configuration. Except in the router but there it's to
make sure RAs are sent and since I only have 6rd, the tunnel is created.

> I checked with wireshark - the RAs look good.

Checked how?

> but so is accept_ra
> $ sysctl -a 2>/dev/null | grep 'accept_ra '
> net.ipv6.conf.all.accept_ra = 1
> net.ipv6.conf.default.accept_ra = 1
> net.ipv6.conf.enp1s0.accept_ra = 0
> net.ipv6.conf.lo.accept_ra = 1
> net.ipv6.conf.wlp2s0.accept_ra = 0
>
> How do I get the default "accept_ra = 1" set on _all_ interfaces?

You use sysctl -w to set those permanently. For testing, manipulate the
virtual files in /proc/sys/net/ipv6/conf/.

Although, to me that looks OK, as in, it's what I have and for me IPv6
works, weird as it is. Forwarding is off and accept_ra is like yours:

net.ipv6.conf.all.accept_ra = 1
net.ipv6.conf.default.accept_ra = 1
net.ipv6.conf.docker0.accept_ra = 0
net.ipv6.conf.enp5s0.accept_ra = 0
net.ipv6.conf.lo.accept_ra = 1

and yet enp5s0 has a public IPv6 address.