Com Hem offering IPv6 via DHCPv6 to its customers
Sunday, December 17. 2017
A month ago my ISP sent information that they're upgrading my connection speed without increasing the monthly cost! Nice. Totally unexpected from them.
Couple weeks ago my internet connection had dropped during night and I just flicked the switch on the cable router and it all came back. What I didn't initially realize, that I had an IPv6-address! WHOA!
Given zero public information about this on their public website, customer portal or anywhere, I just saw that on my network interface while investigating an another issue. They are broadcasting router advertisements and allocating a /64 from 2A04:AE00::/26 (SE-COMHEM-20140210). It looks like this on radvdump:
interface enp1s0 {
AdvSendAdvert on;
# Note: (Min,Max)RtrAdvInterval cannot be obtained with radvdump
AdvManagedFlag on;
AdvOtherConfigFlag on;
AdvReachableTime 600000;
AdvRetransTimer 0;
AdvCurHopLimit 64;
AdvDefaultLifetime 9000;
AdvHomeAgentFlag off;
AdvDefaultPreference high;
AdvSourceLLAddress on;
AdvLinkMTU 1500;
}; # End of interface definition
Since the O-bit for "other" (AdvOtherConfigFlag on) is enabled, it means that a DHCPv6-request will get more usable information. A DHCPv6 lease will look like this:
lease6 { interface "enp1s0";
ia-na xx:xx:xx:xx {
starts 1512476381;
renew 302400;
rebind 483840;
iaaddr 2a04:ae07:yyyy:yy::yyyy {
starts 1512476381;
preferred-life 604800;
max-life 2592000;
}
option dhcp6.status-code success;
}
option dhcp6.client-id 0:1:2:3:4:5:6:7:8:9:a:b:c:d:e:f:10:11;
option dhcp6.server-id 0:1:0:1:53:f:97:74:0:50:56:a8:22:a4;
option dhcp6.name-servers 2a04:ae3a:ae3a::1,2a04:ae3a:ae3a::2;
}
It works and is fast and all, but ... (there's always the but part). Given SLAAC, they issue only a /64 prefix. Why is that a problem you ask. Well, to be able to issue an IPv6 address to all devices in my LAN, that's not enough.
I tried sending a Prefix Delegation -request via DHCPv6, but no. They didn't honor that request. Should that worked, I'd be happy. I'd have my own /48 prefix for my LAN-devices.
In the current form Com Hem's IPv6 is mostly useless as none of my actual devices have IPv6 addresses in them. I'm investigating this and if/when I find a solution for this, I'll post something about it. Meanwhile, if you know how to get a prefix out of them, please inform!
