How to properly configure a /128 IPv6?

[eduperez]

In it's infinite generosity, my ISP has decided to assign a whole /128 (public!) IPv6 address to my LTE connection... well, being LTE, I can understand it is supposed to feed a single mobile phone, instead of a router.

I can reach the router on IPv6 from outside, and I can live not having IPv6 at all, for the other devices in my network. The question is, is there anything else I could/should do, to consider this a proper configuration?

[NPeca75]

Hi @eduperez

as you have single v6 addr, you could masquerade private (fc00/fd00) LAN addresses to single WAN v6 address with

config zone
    option name 'wan6'
    option input 'ACCEPT'
    option output 'ACCEPT'
    option forward 'REJECT'
    list network 'wan6'
    option masq6 '1'

and you could make port forward to specific LAN device with

config redirect
    option dest 'vlan202'
    option target 'DNAT'
    option name 'frater80v6'
    list proto 'tcp'
    option src 'wan6'
    option src_dport '80'
    option dest_ip 'fd00:25:202::1004'
    option dest_port '80'

[bmork]

@eduperez

In it's infinite generosity, my ISP has decided to assign a whole /128 (public!) IPv6 address to my LTE connection...

Are you sure? I believe this is hard to do on a mobile connection. A single /64 is much more likely. But your modem might try to fool you by making up some interface identifier

[AndrewZ]

If you're using QMI, /128 on the outer interface is hardcoded in the connection script
Highly likely you have /64 as @bmork said.

[eduperez]

I do not really need IPv6, but I also like to overcomplicate everything, so I will probably end trying this. Thanks!

[eduperez]

@bmork @NPeca75 : I am sure 'ifconfig' shows only a /128 and nothing else, but I am using QMI. I will try to tinker with the parameters, and see what happens. Many thanks!

[eduperez]

I just activated option "dhcpv6" on the WAN config, and now I receive a /64 from my ISP; many thanks!

[_bernd]

Maybe play around and request a larger prefix and see what's happening. Because as far as I know LTE 5g and such have no limitations of how the ISP routes to you. It is not uncommon to serve with LTE routers/modems many clients behind it. Then a single address would put us back into the late last millennia.