[franklyworks]

Android supports SLAAC and has good support transitional tech like xlat464 and DHCP option 108.

I have used these on my network and office to move to IPv6-only for Android.

What about lack of DHCPv6 prevents you from using IPv6 on Android?

[candiddevmike]

I can't run SLAAC and DHCPv6 at the same time without giving devices multiple addresses, and Android doesn't support DHCPv6, so I'd have to carve out a separate, SLAAC-based, android-only network. And then figure out firewall rules, multicast reflection, etc.

[gspr]

I thought this was a problem too. Then I realized that addresses are not in short supply, so I stopped caring that some devices get multiple addresses. The ones I care about are handed out over DHCPv6, and the firewall works accordingly. The rest gets basic connectivity and nothing else.

Works great for me.

[candiddevmike]

Don't you have problems with clients using the wrong source address and not matching firewall rules?

[gspr]

No. Admittedly, my firewall rules are all about granting something extra beyond the basics. I only do this for clients I care about anyway, so I can always tell them to use the right address.

[kstrauser]

Different person here, but no. I never write firewall rules based on individual source addresses. They’re too easy to fake. And with IPv6’s privacy extensions, you never know what source address a given machine will have anyway.

[gspr]

Interesting. How do you deal with destination addresses on your local network? DHCPv6 like the other poster and myself?

[kstrauser]

I haven’t had a need for DHCPv6. I’d use DNS (or better, mDNS) to assign a hostname to the destination’s fixed IPv6 address or ULA, both of which are static. I don’t ever manually assign an IPv6 address to a host, though. I just let SLAAC do the thing it was designed for.

[justincormack]

Why is giving multiple addresses a problem?

[candiddevmike]

No control over which source address is used. I'm assigning a lot of clients DHCP reservations so I can use static addresses for monitoring and firewall rules. With multiple addresses on the same network, clients may use their SLAAC address which won't match the firewall rule.

[db48x]

That still doesn’t really make sense. Why not run SLAAC on one subnet and have a single firewall rule for the whole thing? You’re not running any major servers on an Android phone, so it won’t be anything complex.

[tsimionescu]

SLAAC can only run on a subnet that's larger than /64, which they might not have access to.

[db48x]

Strictly speaking it can and does run on subnets that are exactly /64. Does anyone actually hand out smaller delegations today?

[justincormack]

There are APIs in Linux to control source address selection but might be fiddly https://www.davidc.net/networking/ipv6-source-address-select...

[franklyworks]

Ah, this makes sense.