From d50258532095582515b56dad5ab8b3ddb62964e5 Mon Sep 17 00:00:00 2001 From: Pavel 'LEdoian' Turinsky Date: Mon, 30 Oct 2023 02:18:48 +0100 Subject: [PATCH] Fix footnotes --- content/forgetting-dns6.rst | 37 ++++++++++++++++++++++++------------- 1 file changed, 24 insertions(+), 13 deletions(-) diff --git a/content/forgetting-dns6.rst b/content/forgetting-dns6.rst index e7eca02..7df6990 100644 --- a/content/forgetting-dns6.rst +++ b/content/forgetting-dns6.rst @@ -42,9 +42,7 @@ There are :s:few many sites that still only support IPv4. To reach them, we need someone, who can reach both the IPv4- and IPv6-land, to go there on our behalf – a proxy. This proxy can be ad-hoc (I often use ``ssh -D``), or there are well-known protocols like NAT64 with DNS64 to do that in a standard and -lightweight manner.[^This is very much the same as when you try to reach the -IPv4-public-land from IPv4-private-land, that is, from a private range of IP -addresses. This is called either just NAT, or NAT44, meaning IPv4-to-IPv4 NAT.] +lightweight manner. [#nat44]_ In that case, the connection looks like this: .. figure:: {static}/images/forgetting-dns6/image3.svg @@ -58,8 +56,7 @@ What I think you didn't know, you need similar workaround to reach the Wikipedia Disclaimer: While I am sad that GitHub lives in the past and it is stupid that they do not have IPv6, I do not want to shame Wikipedia in particular. It is just an example I found out recently. I am aware of several other -sites suffering from the same problem, including at least one IPv6 test.[^There -are several more tests that do not even have the AAAA record, lol.] (It would +sites suffering from the same problem, including at least one IPv6 test. [#test-aaaa]_ (It would be nice if they added the missing piece in the puzzle, though.) Enter DNS @@ -75,9 +72,7 @@ There are three interesting types of records: A records give IPv4 addresses, AAAA give IPv6 addresses, and NS give names of servers who know about the particular subtree of the database. And to actually resolve the final AAAA record, the (recursive) resolver starts at the *root zone* and tries to find -the answer.[^In my example, there is a recursive DNS resolver external to my -machine, in order not to complicate it too much. Yes, the real deployment is -often trickier.] The resolution algorithm can be visualised like this: +the answer. [#dns-simplification]_ The resolution algorithm can be visualised like this: .. figure:: {static}/images/forgetting-dns6/image4.svg :width: 100% @@ -103,11 +98,7 @@ similar to the SSH, NAT64 and NAT44 ones mentioned earlier. This may not be much of a problem for many people. But if you have any reason to use your own recursive DNS server (privacy reasons, DNSSEC validation, ISP provides bad service, you are the ISP, …) *inside* an IPv6-only network, you *will* have -issues.[^I have not yet tried to run a recursive DNS in a network with DNS64 -and NAT64. Could be fun :-D My wild guess is that I would need CLAT (i.e. the -full 464XLAT deployment) to make that work, since the resolver is connecting -directly to IPv4 addresses and would need to learn to use NAT64 to resolve -them. (The CLAT could be built right into the resolver, though).] +issues. [#dns-behind-nat64]_ Example: Wikipedia ================== @@ -310,3 +301,23 @@ subdomain, which, incidentally, was the *only* one that was IPv6-capable. So, while all the correct records were present in DNS (somewhat/somewhere), this still meant that IPv6-only resolution was doomed to fail, because the IPv6 nameserver chain was broken. + +----- + +.. [#nat44] This is very much the same as when you try to reach the + IPv4-public-land from IPv4-private-land, that is, from a private range of IP + addresses. This is called either just NAT, or NAT44, meaning IPv4-to-IPv4 NAT. + +.. [#test-aaaa] There are several more tests that do not even have the AAAA + record, lol. + +.. [#dns-simplification] In my example, there is a recursive DNS resolver external to my machine, + in order not to complicate it too much. Yes, the real deployment is often + trickier. + +.. [#dns-behind-nat64] I have not yet tried to run a recursive DNS in a network + with DNS64 and NAT64. Could be fun :-D My wild guess is that I would need + CLAT (i.e. the full 464XLAT deployment) to make that work, since the + resolver is connecting directly to IPv4 addresses and would need to learn to + use NAT64 to resolve them. (The CLAT could be built right into the resolver, + though).