Hi, Am 12.04.20 um 20:12 schrieb Uwe Schindler: > Hi, > >> thanks for the elaborate reply! > > No problem!
and thanks again :-). > >> There's a slightly more special case for us: We have one central firewall >> (which >> gets the full /56 net on the upstream interface routed to it) and most >> gateways >> are separate nodes >> (i.e. most VLANs are not connected to the central FW). >> So I believe in that case I just need an ip6tables rule (per /64 subnet) on >> the >> central firewall to redirect all traffic to the gateway for the /64 subnet, >> right? > > It's important to don't have the /56 or /64 network assigned to an interface > on the router (otherwise you would need proxyNDP)! Noted. Indeed, that's reasonable, and achieved by design for those VLANs not connected to the central router ;-). > If it's prefix delegation, don't assign the 64 or 54 subnet to any interface > on the main router, just bring interfaces up and assign link-local-addresses > to them! On the central firewall just do routing with link-local addresses > (basically, this subnet goes to this adaptor and this mac address - as link > local addresses are basically MAC addresses). Of course the packet filtering > uses the global addresses, but the routing is done with link-local. > > The router box gets the packets from the provider all delegated to its own > link-local address of the upstream interface (that's what most providers do, > including DSL providers with PPP or servers in data centers like Hetzner). So > all incoming packets are sent to the same fe80:XXXX address based on the MAC > known to upstream or negotiated via PPP and the router just forwards them > based on the global address inside of the packets. In our case, they waste a dedicated /64 global address network for the connection network between our firewall and their endpoint... That also works, but it's rather wasteful of course ;-). > In the routing table of the main firewall you just add entries like global > subnetA/64 goes to link-local address fe80:xxxx on interface XY, and so on. > If you don't like the automatic assigned link-local-addresses based on the > mac interface you can easily change them. In my office I have the router > assigned fe80::1, you could assign fe80::2, fe80::3 to the secondary > routers's network interfaces and then routing tables look easy: > > 2001:abcd:1234:1::/64 => fe80::2@en1 > 2001:abcd:1234:2::/64 => fe80::3@en1 > 2001:abcd:1234:3::/64 => fe80::email@example.com (a VLAN #24 on en1) > 2001:abcd:1234:3::/64 => fe80::4@en2 (other network interface) > > Fe80::2, 3, 4 are the separate boxes which route the traffic and have the > dnsmasq. If you don't want to use fe80 link-local addresses, you can use > ULAs, but for routing purposes the link-local ones with interface name are > the easiest. Thanks, that example clarified it for me. Good thinking in using the link-local addresses here, that's completely sufficient. It really helps to talk about these things to clear up my mind from the IPv4 legacy of thinking. > > Another idea is to use one of the /64 subnets as the "inter-router" > communication, but that's not needed for IPv6, because we have > link-local-addresses for that purpose! > > On the internal routers you only assign the full global 64 subnet to the > client facing network adaptors. The connection to the router uses a > link-local address only (as described before). No additional firewalling is > needed, you just need to setup routing entries like above (the other way > round). Thanks, that cleared up my last question completely. Now I just have to explain my colleagues and we can start implementing that in the next weeks (in slow steps, but it seems much more straightforward than I thought) :-). >>> Just some recommendation: I'd NOT go with DHCPv6, as no Chromebook or >> Android device supports it. I'd go for SLAAC. Very easy. As you can setup a >> separate /64 subnet (up to 256 of them), you have enough flexibility to >> handle >> all of them in a separate network with full /64 SLAAC address space. Each of >> those networks have firewalling on the router box and are delegate to the >> network switch .e.g, via VLANs. >> >> I know (while I knew about Android, good point about the Chromebooks!). Our >> main usecase is addressing of Linux servers (i.e. there will only be "DHCP >> reserved" entries). >> Indeed, for a general purpose network (one of those /64s), we need to think >> whether we'll go with DHCPv6 (and lose Android and Chromebooks) or really >> stay with DHCPv6. For now, I'll plan with DHCPv6 ;-). > > No problem. You can have both, depending on subnet. > > Uwe > Cheers and thanks again, Oliver _______________________________________________ Dnsmasq-discuss mailing list Dnsmasqfirstname.lastname@example.org http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss