Time to cash in?
My company has just turned off all ip6 connectivity for its corporate laptops because it’s considered a security risk. I disagree, but I do agree that having 4 and 6 is a higher risk than 4 alone or 6 alone, and 6 alone sadly still doesn’t work reliably.
All the “promise” of ip6, direct connections etc, were lost when stateful firewalls became required and memory became cheaper than $20 a megabyte. Some bespoke old protocols don’t like ports changing, which can be a problem, but it’s a very small number and easier to work around with modern protocols than support a dual stack environment securely for the majority of places that struggle securing a single stack.
With ipv4 you have a two tier internet. Computers talk to servers, servers talk to servers, computers can't talk to computers so every video call must be routed through a server.
Some people will mention stateful firewalls. They're pretty easy to holepunch through because you just need each side to send a packet to the other, then each firewall sees it as an outgoing connection and allows it. It's nothing like IPv4 NAT.
For example here is how to achieve the same result in PF, note the single additional operator needed to specify nat.
block in on $EXT_IF
#NAT
pass in on $INT_IF to any rdr-to $EXT_IF
#statefullfirewall
pass in on $INT_IF to any
That the server can figure out that two computers in the same house are different since your laptop and phone no longer share the same ipv4 address but instead have two ipv6 address?
Your phone and laptop can just have multiple ipv6 addresses and rotate through them regularly... as apple does by default https://support.apple.com/en-ca/guide/security/seccb625dcd9/...
Security? NAT is not a firewall, you need a firewall, and switching to IPv6 does not remove your firewall.
Before IPv6: The server gets "1.2.3.4:56789" for your device. After IPv6: the server gets "1:2:3:4::56" or whatever for your device. In either case, if the server makes a connection to 1.2.3.4:56789 or 1:2:3:4::56, your router sees the packet and firewalls the connection. Cool.
Want to give me a concrete example of where IPv6 is hurting my privacy or security, because I've been using it for over a decade with zero mishaps, zero privacy issues, zero security issues (to my knowledge at least)
Using a random address (Privacy Extensions) solves this problem though, but do we expect everyone to know what that is and check it's enabled? Mine wasn't enabled by default (on Linux) and I only noticed when a bittorrent site warned me.
* https://support.apple.com/en-ca/guide/security/seccb625dcd9/...
As does Windows (since Vista), and Android (8+).
So why are we still talking about this?
I've only read that on HN, I've never heard this anywhere else. Since it's been a good 20+ years since my CCNA (and haven't needed to renew it since), could you please offer a real-world example where NAT is not a firewall w/ practical examples relating to 99.9% of cases of home use? I just can't get why people say this a lot here.
NAT works and passes the grandma test. If grandma buys a crappy vulnerable 40$ printer and plugs it in, even if it accepts unauthenticated stuff on every local port, you will not be able to connect to it behind NAT. So what's the difference? The only way I could think this can apply is if the ISP is compromised or criminally mismanaged, in which case you probably already have bigger problems.
But why would you rather have an always-broken network that might block attackers instead of a deliberate "deny incoming" rule that does exactly what you want -- and that you can punch holes in if desired?
Instead we have apps circumventing this accidental barrier with STUN, uPNP, etc with little/no oversight and we also regularly encounter brokenness.
Even if you want to ignore the fact that most attacks arrive via outbound connections and restrict the discussion to just inbound ones... remove NAT and the exact same set of people that could connect to you before can still connect to you, so it's doing nothing for your inbound connections.
Well-regarded networking architect, author, and instructor:
* https://blog.ipspace.net/2011/12/is-nat-security-feature/
> NAT works and passes the grandma test.
So does my Asus with a default deny IPv6 rule on incoming connections.
You're more likely to click on a link that installs malware that attacks your network from the inside, and that attack works regardless of IPv4 or IPv6.
Treating a firewall as some impenetrable moat has not been network security practice for a decade(+), and waving around RFC 1918 address space like systems with a 10.8 or 192.168/16 can't get infected is lazy thinking. It leads to complacency: I'm behind NAT, I'm safe.
(All of that hinges on the key question that people seldom ask: what is being protected, and from who. The "two-tier" Internet is, in a way, pointing out a case where regular users are seen as threat actors.)
I had a very concreteish security risk with IPv6 and openvpn. At least in Debian config openvpn tunneled only IPv4 by default. I only noticed this by being surprised I got results tailored to my origin country instead of the VPN out node country.
It's eternal (dual stack) paper cuts like this why just turning IPv6 off makes life a lot easier.
If your corporate laptops are running Windows, then you're going against the officially supported configuration of the vendor (Microsoft):
> Internet Protocol version 6 (IPv6) is a mandatory part of Windows Vista and Windows Server 2008 and newer versions.
> We don't recommend that you disable IPv6 or IPv6 components or unbind IPv6 from interfaces. If you do, some Windows components might not function.
* https://learn.microsoft.com/en-us/troubleshoot/windows-serve...
> Cg nat does everything that’s needed […]
Except for making it convenient for end-user to, say, play P2P video games, or host Mindcraft servers, etc.
> […] and 6 alone sadly still doesn’t work reliably.
It's so unreliable that half of all Internet traffic uses it. It's so unreliable that Microsoft has been going IPv6-only in their corporate networks (a decade ago):
* https://labs.ripe.net/author/mirjam/ipv6-only-at-microsoft/
It's so unreliable that Google is now 99% IPv6-only/mostly on their corporate networks: