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Is `sysctl -w net.ipv6.conf.eth0.accept_ra=2` still necessary?
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Asked by beamerblvd on Feb 6 2018, 2:12 AM.

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According to this documentation, there is no configuration option for listening to / accepting router advertisements from neighbors. VyOS apparently supports this, but the documentation says that you must do this to enable it:

sysctl -w net.ipv6.conf.eth0.accept_ra=2

Furthermore, it says that you must do this on every boot, as it does not survive reboot.

Is this still applicable in the latest 1.1.8? What about the upcoming 1.2.0? We definitely need some roadmap for a reboot-survivable config path to this.

Answers

beamerblvd
Updated 538 Days Ago

And I found my answer.

The answer is yes ... and no. Yes, there isn't yet anything like this:

set interface ethernet eth1 ipv6 accept_ra [never=0|only-if-no-forwarding=1|always=2]

However, version 1.1.8 added this little gem, which works perfectly and survives reboot:

set system sysctl custom $key value $value

So I did this:

set system sysctl custom net.ipv6.conf.eth0.accept_ra value 2

And I'm receiving the default route from my neighbor now.

I still believe that we need a clearer config path for this very common value (see recommendation above), but this meets my needs.

gadams
Updated 290 Days Ago

Yes, I've run into this, too. I have a fix that makes that step not necessary. It is covered in this EdgeRouter forum discussion, which contains the excellent summary:

when you configure an interface for SLAAC, it should automagically set accept_ra=2 [...]. It is a router afterall, it is always going to be forwarding.

I'll create a task for this and send my pull request shortly.

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