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Subnets and reverse DNS
![[si]](/s/countries/si.gif) Shadow Hawkins on Wednesday, 06 April 2011 23:52:42
I have just a quick question.
Is it acceptable to request a subnet for the sole reason of being able to set the reverse DNS record for one host? There would be only one host on the whole subnet.
Subnets and reverse DNS
![[gb]](/s/countries/gb.gif) Shadow Hawkins on Sunday, 17 April 2011 19:20:09
Well you are allowed to request a subnet for personal use! It is kind of how IPv6 works, you are not being greedy :)
This is also the only way you can setup reverse DNS and setting up a working reverse DNS is not against the law, some network related services require/mandate it for extra security.
It is also kind of expected that ideally you would have a firewall/router device at your site between your equipment (the one host you have) and the public Internet. This does not have to be the same piece of equipment.
Therefore in order to operate IPv6 in this situation you would be required to obtain a subnet. Gasp!
So therefore I can't see anything wrong with your request. There are indeed enough possible subnets around for every man-woman-child on planet (and forecast to be on planet for next 100 years) to have some million each to their name, so might as well get started and take a single one for now.
Subnets and reverse DNS
Shadow Hawkins on Monday, 18 April 2011 00:15:57
Well, you are correct as far a IPv6 in general is concerned. There are enough (and way more) /48 subnets for everyone. I was asking, however, if this is a violation of SixXS's specific policy.
I find it rather strange that all subnets are /48 here at SixXS. On PoP I am primarily using (simbx01), there are two /40s designated for subnets and there are 448 subnets active at the moment. That's almost 1/128 of a /32. I expect that demand for IPv6 tunnels (and hence subnets) will skyrocket over the next few months due to IPv4 exhaustion and I don't think that ISPs will be happy about designating large parts of their /32 just for SixXS subnets (especially if they have a different policy for subnet size for their own clients).
This is why I am asking whether requesting a subnet solely for rDNS delegation is acceptable under SixXS policy. My host is performing tunneling directly and there is no firewall in between (well, Windows Firewall is ;), so it is really a single host by all definitions.
I may be completely wrong though and this predicament is completely irrelevant. It is also true that once you DO have a subnet, you start to experiment :) You can for example set up IP-based virtual hosts in Apache or such things.
Anyhow, my subnet request was accepted nevertheless so I guess it is not a violation :)
Subnets and reverse DNS
Shadow Hawkins on Wednesday, 20 April 2011 23:26:21
There is a policy SixXS policy about not doing it to gain reverse DNS naming for IRC (vanity rdns). While I don't do this myself, I also don't appreciate the problem, my personal opinion is so what.
However it is accepted that rdns is a necessary function of using the internet, for example SSL (and other improved security mechanisms). There are alternative solutions but one might think of these as being like NAT a bandaid for the problem that is IPv4.
I think the existing SixXS PoPs will run out of steam well before there are concerns by their hosted ISPs to require more address space.
Each ISP with the single standard /32 is able to manage and allocate a /32 worth of sub-networks. So this is like the current number of individual addresses in IPv4 can now each be a network within a single ISP. Each of these sub-networks can be a /64. Even when a single ISP exhausts this pool they can get another such allocation.
There are maybe only a maximum of 128k ISPs in whole the world (even accounting for future growth) and 128k into 4gig goes 32k times. So they can extend their allocation 32k times and still not be taking more IPs than any other ISP is entitled too. But obviously there are small ISPs and big ISPs and obviously the whole 128bit of IPv6 address is not available for unicast use.
SixXS is quite generous with providing /48 to users, but for regular mobile devices and other consumer grade internet termination maybe they will only get a single network /64. Since it is possible to run both automatic addressing with the same network (via ethernet MAC and some amount of fixed addressing like <my-network-prefix>:0000:0000:0000:0001 since the automatic addresses always enforce xxxx:xxff:fexx:xxxx in the middle).
However even continuing /48 for all; how many ISPs in the world have more than say 20million customers? This would require them to go back to their RIR around 300 times to extend their IPv6 ranges. But they could extend upto 32k times and still not be considered greedy.
So it looks like about 3 ISPs could between them service 6 billion customers with a /48 for each customer and there would still be room for another 131069 equal sized ISPs to exist in the world.
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