IPv6 genuinely made some really good decisions in its design, but I do question the default “no NAT, no private network prefixes” mentality since that’s not going to work so well for average Janes and Joes
No NAT doesn’t mean no firewall. It just means that you both don’t have to deal with NAT fuckery or the various hacks meant to punch a hole through it.
Behind NAT, hosting multiple instances of some service that uses fixed port numbers requires a load-balancer or proxy that supports virtual hosts. Behind CGNAT, good luck hosting anything.
For “just works” peer to peer services like playing an online co-op game with a friend, users can’t be expected to understand what port forwarding is, let alone how it works. So, we have UPnP for that… except, it doesn’t work behind double NAT, and it’s a gaping security hole because you can expose arbitrary ports of other devices if the router isn’t set up to ignore those requests. Or, if that’s not enough of a bad idea, we have clever abuse of IP packets to trick two routers into thinking they each initiated an outbound connection with the other.
IPv6 has two main types of non-broadcast addresses to think about: link-local (fe80::) and public.
A device can self-assign a link-local address, but it only provides direct access to other devices connected to the same physical network. This would be used for peer discovery, such as asking every device if they are capable of acting as a router.
Once it finds the router, there are two ways it can get an IP address that can reach the wider internet: SLAAC and DHCPv6. SLAAC involves the device picking its own unique address from the block of addresses the router advertises itself as owning, which is likely what you’re concerned about. One option for ensuring a device can’t just pick a different address and pretend to be a new device is by giving it a subset of the router’s full public address space to work with, so no matter what address it picks, it always picks something within a range exclusively assigned to it.
Edit: I butchered the explanation by tying to simplify it. Rewrote it to try again.
In most cases, the router advertises the prefix, and the devices choose their own IPv6. Unless you run DHCPv6 (which really no-one does in reality, I don’t even think android will use it if present).
It doesn’t allow firewall bypass though, as the other commenter noted.
Unless you run DHCPv6 (which really no-one does in reality)
Question for you since I have very little real world IPv6 experience: generally you can provide a lot of useful network information to clients via DHCP, such as the DNS server, autoconfig info for IP phones, etc. how does a network operator ensure that clients get this information if it’s not using DHCPv6?
As a tech nerd who self hosts stuff, I’m more like “what is IPV6 and why is it causing me issues, I can’t figure this out, I guess I’ll disable it, wow my problems are fixed now.”
I guess I can see why people don’t like it, as it’s caused me issues, but just because I don’t understand it doesn’t mean it’s dumb. I’d need to understand how it works before I could say anything about it, positive or negative. I guess all I could say is that it’s been way less intuitive to me, I can’t memorize the numbers, and the reason it exists makes sense. Beyond that, I unno.
I should probably spend the time to learn about it, but I already have a full time job where I work on computers all day, I’d rather focus on my other hobbies while I’m at home.
It’s not terribly difficult to learn when you avoid trying to relate it to IPv4 concepts. Particularly: forget about LAN addresses and NAT, and instead think about a large block of public addresses being subdivided between local devices.
instead think about a large block of public addresses being subdivided between local devices.
Thinking about all my devices being exposed like that gives me the heebie jeebies. One public facing address hiding everything else on a private network is much less frightening to my monkey brain.
IP4 is running out, that’s the problem. Or better, IP4 is hoarded by companies and they don’t give them up. The insane amount of network devices every human being uses on a daily basis doesn’t make the situation better. It exploded the last 10 years and only gets worse. The fuckery ISPs are doing to solve it without IP6 is insane, fuck cgnats and co. The whole networking world would be so much better to get it over with and adopt IP6 everywhere and let the hoarders drown in their mountain of IP4.
My ISP gave me a IPV6 router. I have it bridged (or whatever the right term is) to another router that serves IPV4 addresses to all my devices. Worked well so far with the added bonus that the ISP can’t see what’s going on within my network.
As a networking nerd, I am endlessly frustrated with how many otherwise smart people are just ‘fuck ipv6 lmao’
Giving me goddamn flashbacks to this https://www.youtube.com/watch?v=v26BAlfWBm8
IPv6 genuinely made some really good decisions in its design, but I do question the default “no NAT, no private network prefixes” mentality since that’s not going to work so well for average Janes and Joes
No NAT doesn’t mean no firewall. It just means that you both don’t have to deal with NAT fuckery or the various hacks meant to punch a hole through it.
Behind NAT, hosting multiple instances of some service that uses fixed port numbers requires a load-balancer or proxy that supports virtual hosts. Behind CGNAT, good luck hosting anything.
For “just works” peer to peer services like playing an online co-op game with a friend, users can’t be expected to understand what port forwarding is, let alone how it works. So, we have UPnP for that… except, it doesn’t work behind double NAT, and it’s a gaping security hole because you can expose arbitrary ports of other devices if the router isn’t set up to ignore those requests. Or, if that’s not enough of a bad idea, we have clever abuse of IP packets to trick two routers into thinking they each initiated an outbound connection with the other.
can you tell me if any device in an IPv6 LAN can just assign itself more IP v6 adresses and thereby bypass any fw rule?
IPv6 has two main types of non-broadcast addresses to think about: link-local (fe80::) and public.
A device can self-assign a link-local address, but it only provides direct access to other devices connected to the same physical network. This would be used for peer discovery, such as asking every device if they are capable of acting as a router.
Once it finds the router, there are two ways it can get an IP address that can reach the wider internet: SLAAC and DHCPv6. SLAAC involves the device picking its own unique address from the block of addresses the router advertises itself as owning, which is likely what you’re concerned about. One option for ensuring a device can’t just pick a different address and pretend to be a new device is by giving it a subset of the router’s full public address space to work with, so no matter what address it picks, it always picks something within a range exclusively assigned to it.
Edit: I butchered the explanation by tying to simplify it. Rewrote it to try again.
In most cases, the router advertises the prefix, and the devices choose their own IPv6. Unless you run DHCPv6 (which really no-one does in reality, I don’t even think android will use it if present).
It doesn’t allow firewall bypass though, as the other commenter noted.
Question for you since I have very little real world IPv6 experience: generally you can provide a lot of useful network information to clients via DHCP, such as the DNS server, autoconfig info for IP phones, etc. how does a network operator ensure that clients get this information if it’s not using DHCPv6?
You can include some information in router advertisements, likely there will be rfcs for more. Not sure of the full list of stuff you can advertise.
For sure I’m quite sure I had dns servers configured this way. I’ll check when not on a phone to see what options there are.
If I recall correctly, you can do stateless DHCPv6 to just hand down a DNS server without also managing the devices’ IP addresses.
As a tech nerd who self hosts stuff, I’m more like “what is IPV6 and why is it causing me issues, I can’t figure this out, I guess I’ll disable it, wow my problems are fixed now.”
I guess I can see why people don’t like it, as it’s caused me issues, but just because I don’t understand it doesn’t mean it’s dumb. I’d need to understand how it works before I could say anything about it, positive or negative. I guess all I could say is that it’s been way less intuitive to me, I can’t memorize the numbers, and the reason it exists makes sense. Beyond that, I unno.
I should probably spend the time to learn about it, but I already have a full time job where I work on computers all day, I’d rather focus on my other hobbies while I’m at home.
It’s not terribly difficult to learn when you avoid trying to relate it to IPv4 concepts. Particularly: forget about LAN addresses and NAT, and instead think about a large block of public addresses being subdivided between local devices.
Thinking about all my devices being exposed like that gives me the heebie jeebies. One public facing address hiding everything else on a private network is much less frightening to my monkey brain.
Ye fuck ipv6 lol. I still have no need to move to it lol.
IP4 is running out, that’s the problem. Or better, IP4 is hoarded by companies and they don’t give them up. The insane amount of network devices every human being uses on a daily basis doesn’t make the situation better. It exploded the last 10 years and only gets worse. The fuckery ISPs are doing to solve it without IP6 is insane, fuck cgnats and co. The whole networking world would be so much better to get it over with and adopt IP6 everywhere and let the hoarders drown in their mountain of IP4.
My ISP gave me a IPV6 router. I have it bridged (or whatever the right term is) to another router that serves IPV4 addresses to all my devices. Worked well so far with the added bonus that the ISP can’t see what’s going on within my network.