Live data from Hacker News

I spent a week without IPv4 to understand IPv6 transition mechanisms

apalrd.net

111–120 of 511 posts

Re: I spent a week without IPv4 to understand IPv6 transition mechanisms

#111
post #67

Earlier quoted context omitted.

My ISP does not allow BYOM (bring your own modem) and assigns me a /64 net, so I have a hard time running an (ipv6) router behind it that would do the firewalling.. I guess I'm stuck with ipv4 for the time being...

Does your ISP's router not have a firewall?

A very very inconvenient one.

Re: I spent a week without IPv4 to understand IPv6 transition mechanisms

#112
post #78

Question from a (relative) IPv6 newbie that wasn't addressed in TFA: Let's say I have a very small home lab. I have a handful of hosts that get their IP addresses via DHCP from my router. In the router, DHCP and DNS are tightly coupled such that the router essentially always knows the MAC address, IP address and hostname of each device. Now I want to run IPv6 on this network as a first-class citizen. Since DHCPv6 is…

Can't answer your main question, but from what I recall, DHCPv6 is kind of necessary anyway. It's the easiest/main way for the client to receive DNS server information, even if default gateway discovery is now down through multicast.

I believe there is another way, but the router has to support it and I forget what it's called.

Re: I spent a week without IPv4 to understand IPv6 transition mechanisms

#113

Earlier quoted context omitted.

> I don't want anything on my network to be globally routable. Then... don't route anything on your network. NAT is address translation, not routing. NAT makes it difficult for you to host services on your network, forcing dependency on cloud services, and when ISPs do it (CGNAT), it makes it just about impossible unless you want to thread your traffic back through a third-party service. If you want a good chance of…

Presumably what thesuitonym means is: Imagine if I'm a medium-sized ISP, or a medium-sized software company, or a medium-sized website. There's a bunch of hassle involved in deploying IPv6. Who knows what it'll do to my users' privacy? Or whether everyone's firewall rules will keep working right? Or whether it'll have some random impact on e-mail deliverability? Or something else? The main benefit of IPv6 is providin…

The sad part to me is that the original IP header included variable-length addresses up to 128 bits, using two 4-bit fields called Source Address Length (SAL), and Destination Address Length (DAL). [1]

Early hardware implementations could have settled on 32-bit, but 48-bit would make more sense to be in line with EUI-48/MAC-48 (ethernet frame). The world could then gradually upgrade hardware over the decade to handle a larger address.

[1] https://www.rfc-editor.org/ien/ien28.pdf

Re: I spent a week without IPv4 to understand IPv6 transition mechanisms

#114

Earlier quoted context omitted.

That's what a firewall is for, NAT does nothing here.

In theory, sure. In practice firewalls can be misconfigured. NAT doesn't have that problem.

NAT cannot be misconfigured? Really?

Re: I spent a week without IPv4 to understand IPv6 transition mechanisms

#115
post #78

Question from a (relative) IPv6 newbie that wasn't addressed in TFA: Let's say I have a very small home lab. I have a handful of hosts that get their IP addresses via DHCP from my router. In the router, DHCP and DNS are tightly coupled such that the router essentially always knows the MAC address, IP address and hostname of each device. Now I want to run IPv6 on this network as a first-class citizen. Since DHCPv6 is…

It isn't really true that DHCP and DNS are coupled, it's just a common feature for power user routers as it's convient.

There are options for IPv6: PFSense, as an example, has "Assisted" RA mode where devices can use SLAAC or DHCPv6, so you have SLAAC for general clients that don't need more (e.g: phones that don't support DHCPv6), but clients that want more can use DHCP to provide specific reserved addresses and DNS names, etc...

Re: I spent a week without IPv4 to understand IPv6 transition mechanisms

#116
post #67

Earlier quoted context omitted.

My ISP does not allow BYOM (bring your own modem) and assigns me a /64 net, so I have a hard time running an (ipv6) router behind it that would do the firewalling.. I guess I'm stuck with ipv4 for the time being...

A firewall can be run "in-line" and not have IP addresses on the interfaces. On a Palo Alto firewall this would be a "virtual wire", and "transparent firewall" or "bridging firewall" would be other common terms. Examples: https://docs.opnsense.org/manual/how-tos/transparent_bridge.... https://docs.netgate.com/pfsense/en/latest/bridges/index.htm... https://www.fortinet.com/resources/cyberglossary/transparent...

Thanks for the hints. Currently, I have a fully routed setup with two routers behind the IPSs box, multiple wireless networks and VPN uplinks (via wireguard) to my servers. It's just that all of this is ipv4, because I don't see any way of doing that using a single /64 network.

Re: I spent a week without IPv4 to understand IPv6 transition mechanisms

#117

Earlier quoted context omitted.

It just makes little sense. With IPv6 instead of NAT deciding that port 2000 maps to 192.168.1.3 port 22, you have a firewall that may or not choose to route to xx:yy:zz or not, and to allow an incoming connection over port 22 to that host or not. If you don't want to accept incoming connections to a given machine or network on IPv6 without NAT that's very easy to have.

Maybe people don't want to disclose the number and purposes of interior machines?

That's what the privacy extensions are for. You can have a regularly changing, randomly generated IP address on each machine.

Re: I spent a week without IPv4 to understand IPv6 transition mechanisms

#118

Earlier quoted context omitted.

It just makes little sense. With IPv6 instead of NAT deciding that port 2000 maps to 192.168.1.3 port 22, you have a firewall that may or not choose to route to xx:yy:zz or not, and to allow an incoming connection over port 22 to that host or not. If you don't want to accept incoming connections to a given machine or network on IPv6 without NAT that's very easy to have.

Maybe people don't want to disclose the number and purposes of interior machines?

Your machines could change their IPs for every second of every day and you wouldn't come close to exhausting your /64 subnet for the next billion years.

Re: I spent a week without IPv4 to understand IPv6 transition mechanisms

#119
post #81

Earlier quoted context omitted.

There's no chance of anybody guessing your infrastructure just by looking at your subnet. (Minimum is /64, which is HUGE!)

Every packet leaving an IPv6 network that isn't NATed has an effective node ID in the packet. No need to guess just look at the packets.

Your machines could change their IPs for every second of every day and you wouldn't come close to exhausting your /64 subnet for the next billion years.

Re: I spent a week without IPv4 to understand IPv6 transition mechanisms

#120
post #92
post #81

Earlier quoted context omitted.

Every packet leaving an IPv6 network that isn't NATed has an effective node ID in the packet. No need to guess just look at the packets.

Most devices support privacy extensions (temporary v6 addresses) for this exact reason. https://www.rfc-editor.org/rfc/rfc4941

This helps mitigate correlations over time but doesn't do anything to mask the identity of the node within a given refresh interval (default one day).
Post reply on HN