2011/6/6 Jeroen Massar <jer...@unfix.org>: > On 2011-Jun-06 16:18, Guillaume Leclanche wrote: >> 2011/6/6 Jeroen Massar <jer...@unfix.org>: >>> ULA would still require NAT66 if you want those hosts to be able to >>> communicate to the outside, unless of course you want to firewall your >>> internal machines based on the global prefix and update those firewall >>> rules and all other dependencies all the time when your prefix >>> changes... (the prefix change is why I mention NAT66 as renumbering is >>> not funny, anywhere). >> >> So, first of all we talk about sites that would have today a dynamic >> IPv4 address. That would be residential, mobile, and SOHO. >> >> In the worst case, these sites can deal with LAN communication using >> ULA addresses, and then any public communication should be handled via >> public IPv6, which are at the moment all in 2000::/3, so clearly easy >> to identify and to put in a firewall. Readdressing the public >> addresses in the LAN is done easily with RAs, or DHCPv6-PD if the LAN >> is subdivided (an still in that case we've most likely left the normal >> SOHO, and we're in a bigger company that will have static v4 and most >> likely IPv6oE or in the home of a geek). > > So did you try the above out? Because if you did you would find the > following minor problems:
No I did not do the test completely, but I've been in the process of seeing how to get things work together in a nice way over the last month. Details below. > - what updates the firewall rules that the internal host has it's > global changed IPv6 address? Swapping out the first 64bits could > work in theory, but might just break existing connections. If you've changed your IPv6 prefix, you will break existing connections anyway. I think in IPv6 the firewall should be filtering what really has to be filtered, that is LAN stuff: netbios, mDNS, nfs, printing, etc. Such a stateless filter can be done simply by "in/out" interfaces without knowing the real IP addresses. You'd need the addresses to maintain a stateful filter (or want address-specific filters, but then again you can't do it better with NAT, where you use the Layer 4 ID to do port redirection). My personal opinion is that it's not necessary, but I admit that views can differ here. > - how do you 'address' the internal services, everything goes by > address or do you allow people to use hostnames? Who updates > those hostnames, and does that hostname mean the internal one > or the external address or both? mDNS should kick in here. That's definitely the way to go for most deployments. Apple did a good job on that one, and it's fair to say that it's a well-thought technology. An mDNS responder should respond with the ULA address of a service (if available of course). I agree that mDNS is in a developing state, and it's not all working as expected for IPv6. > > - when you have printer configured, and you take your laptop to > the lake, and you want to print, does it use the internal address > or the external one? Corner case. If you do that, you start your VPN and you're in your LAN. > And then the other bunch of issues which effectively come down to a > split-horizon view of a network. Folks are worried about IPv4+IPv6 > fallback-connect issues as their browsers try both IPv6 and IPv4, be > very worried when a host is both ULA and global though, which one to > pick and when... There's a major difference here. IPv4 vs IPv6 selection is left to the application, or if available, to a high level library with named based sockets. ULA vs Global is left to the OS, which will do the selection following IETF standards. This means that applications don't have to be fixed. > > One of the biggest things with IPv6 which IPv4 does not allow for > everyone on the world (as it works too with IPv4 if you got a large > enough chunk of addresses) is that your address is globally unique, and > thus you can keep on sending packets to that single address without > issues. That concept breaks with ULA. No, ULA has to be used for LAN-LAN communications, and Global for internet communications. Each equipment should have both addresses. If this is not respected, and ULA is used as RFC1918 with NAT66, then the goal is not reached, and as you say, it doesn't make much sense. > > ULA is nice, it solves some problems, but it does not solve the problem > when a host is also connected to a public network and does get a > globally unique address through there. ULA does solve the problem when > the network is not connected to anything else and you don't want to > bother with getting a prefix for a private network. > >> And finally, 6rd is a transition technology, and will be certainly >> removed in a few years to go to IPv6oE, once incompatible hardware >> will be phased out. Well, that's a wish, don't take it for granted :) > > Right, because like we have not been doing IPv6 tunneling for about 18 > years already... and so much went native. The difference is that in the last year, big ISPs and big content providers have been busy activating it, so the comparison with the last 18 years, where it was a toy and research thing, is no longer relevant. Guillaume _______________________________________________ swinog mailing list swinog@lists.swinog.ch http://lists.swinog.ch/cgi-bin/mailman/listinfo/swinog
