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> it also makes stuff like NAT, congestion control and QoS a lot less robust

That's a feature, not a bug. NAT is cancer. It killed the open internet by enabling a particular lazy form of "security" that forced everyone to hand control of their most important data to cloud services.

QoS is worse but has less fallout due to less deployment.

>NAT is cancer. It killed the open internet by enabling a particular lazy form of "security" that forced everyone to hand control of their most important data to cloud services.

Sorry I dont follow. What Cloud Services?

All cloud services.

Personal computers and devices are not allowed to talk to each other on the internet. They are only allowed to talk to specially designated servers -- specially designated by virtue of having a public IPv4 and open port. Enforcement happens through liability: if you put data in a cloud service and the cloud service gets hacked, it's the cloud service's fault, but if you run a program on an open port and the program gets hacked, it's your fault, not the program's fault. This is an arbitrary social choice that follows directly from enshrining NAT as a "best practice." Even the term "open port" presupposes that there is something unnatural about plebian computers talking to each other on the open internet! This effectively forces services to be centralized, or at least pushes very strongly in that direction.

Of course, we can quibble: what about video conferencing? What about gaming? They use direct connections! Yes, but they pay an extraordinarily steep complexity and reliability price to obtain them and the solutions still wind up using centralized servers. They are exceptions that prove the rule because they allow us to observe how "stepping out of line" is discouraged. It's an accidental line drawn by monkies rather than an intentional line drawn by lizard people, but it's strongly enforced and society-shaping all the same.

It's totally wild to consider the social and market consequences of NAT, the unassuming lazy and kludgy security hack. It got out of hand and reshaped the internet, the technology market, and society from the ground up! That's hardly even an exaggeration!

NAT is literally the only thing stopping every single personal device in the world from being hacked. It may be a kludge, but it's the best kludge in all of technology. And what do you have against QoS? Would it be better if your VoIP calls stuttered every time you loaded a fat web page?

> NAT is literally the only thing stopping every single personal device in the world from being hacked.

This is so wrong that it must be satire. NAT provides the very most basic protection possible, easily replicated (and surpassed) by every firewall that comes stock with every modern OS, and is completely insufficient (and not even necessary) to prevent personal devices being hacked.

I'll buy this for firewalls in end-user routers, but if you put the firewall on the personal device it's gonna get disabled the first time it supposedly interferes with a videogame or a movie stream or whatever. :(

NAT enables dogshit endpoint security, yes, but that's the problem. Without NAT as a crutch, endpoint firewalls and service security wouldn't suck. Compared to other feats of security engineering the industry has undertaken in order to make centralized cloud services happen, namely JavaScript and the ability to safely run untrusted code from the nastiest corners of the internet at high performance, this would be downright trivial. It just never happened because we had NAT.

It's really not. Like, really, really not. I won't try to make the case here, but just know that assertions like that aren't going to come across as credible. The systemic effects from NAT have actually made things worse.

No it isn't, that's basic stateful firewalling. NAT in no way provides security. At all.

The fact that a kid with a port scanner can't remotely connect to and exploit your printer is due to NAT not being able to route the traffic, whether you have a stateful firewall or not. The majority of internet-addressable devices in the world do not have firewalls. Hence, NAT keeps most devices safe from drive-by RCE. There are plenty of attacks to get around that, but by default, nothing else protects random devices like NAT does.

> The majority of internet-addressable devices in the world do not have firewalls. Hence, NAT keeps most devices safe from drive-by RCE.

According to System Preferences, my Mac's firewall is currently turned off. Here are the current non-NATed IPv6 addresses on it:

   $ ifconfig en1 | grep inet6 | grep -v fe80
 inet6 2607:f2c0:93c7:fe00:144f:b9a3:bcd4:ef6 prefixlen 64 autoconf secured 
 inet6 2607:f2c0:93c7:fe00:e04c:f356:f2:b9e2 prefixlen 64 autoconf temporary

You should be able to ping(6). Can you connect to tcp/22? If not, it shows that my router's stateful packet inspection (SPI) works even when NAT isn't present.

* http://www.ipv6scanner.com/cgi-bin/main.py

The results of an nmap of one of those address from the system itself:

    PORT     STATE SERVICE REASON
    22/tcp   open  ssh     syn-ack
    111/tcp  open  rpcbind syn-ack
    1022/tcp open  exp2    syn-ack
    2049/tcp open  nfs     syn-ack

If you have a device doing NAT, then that device is already doing SPI, and so the NAT part is redundant. It is the SPI that gives you the security.

Well first, IPv6 doesn't need NAT, and mostly never uses NAT. If IPv6 devices used NAT, they would be protected. But since they aren't using NAT, they aren't protected. You're right that devices that enable IPv6 (and network routers that give out IPv6 addresses) are not protected by NAT, but luckily it's still a small amount of traffic/devices worldwide. But this is changing, and so NAT won't help people for much longer.

Second, SPI isn't used for security here. It's true that SPI is used by NAT, and that SPI can be used to prevent, say, a specially crafted packet from passing from a public network through a router into a private network. But something other than SPI has to actually enforce that. That "something" is usually extra features of the network stack, like disabling source-routing, reverse-path filtering, ARP filtering, etc. All SPI is doing is helping the NAT engine track the connections it is translating.

For "good faith" traffic (that is, not crafted by an attacker to work around crappy NAT routers) NAT still provides security. Actually it's not NAT at all that's providing the security - it's just the routing. You can't pass traffic from a public network into a private network, and almost all devices behind NAT are on private networks. So NAT provides security merely by keeping devices on a private network.

> But since they aren't using NAT, they aren't protected.

I just demonstrated that protection exists without NAT.

> […] but luckily it's still a small amount of traffic/devices worldwide.

I don't think this is correct. Just about all devices on a cellular/mobile network nowadays are probably using IPv6 natively, with CGNAT for IPv4. That's a lot of devices.

* https://blogs.akamai.com/2016/06/preparing-for-ipv6-only-mob...

An experiment: temporarily disable Wifi on your cell phone, go to your browser, search of "what is my ip address". Chances are that you'll see an IPv6 address there: if using Google they'll return something an IPv6 address at the top, and a list of different web sites that do the same thing. If you go to a website you'll probably get an IPv6 and an IPv4 address.

> But something other than SPI has to actually enforce that.

Connection tracking is sufficient for most modern protocols (i.e., not (active) FTP):

> A stateful firewall keeps track of the state of network connections, such as TCP streams, UDP datagrams, and ICMP messages, and can apply labels such as LISTEN, ESTABLISHED, or CLOSING.[2] State table entries are created for TCP streams or UDP datagrams that are allowed to communicate through the firewall in accordance with the configured security policy. Once in the table, all RELATED packets of a stored session are streamlined allowed, taking less CPU cycles than standard inspection. Related packets are also permitted to return through the firewall even if no rule is configured to allow communications from that host.

* https://en.wikipedia.org/wiki/Stateful_firewall

* https://en.wikipedia.org/wiki/Firewall_(computing)#Connectio...

> Actually it's not NAT at all that's providing the security - it's just the routing.

Yes, that's exactly my point. And as part of routing packets one can inspect their headers and drop or allow them as desired.

I think we're sort of agreeing on the same things. NAT protects devices, and stateful firewalls protect devices, and if you have neither, you're not protected. My point was that more devices exist behind NAT than come bundled with a stateful firewall, hence NAT protects more devices. The NAT devices/routers might additionally have a stateful firewall (which really only protects the router, not the other devices), but I wouldn't trust it as much as the security of a non-routable network.

> My point was that more devices exist behind NAT than come bundled with a stateful firewall, hence NAT protects more devices.

The popularity of a mechanism does not necessarily correlate with the effectiveness of its security. The fact that we're using IPv4 with NAT+SPI versus IPv6 with SPI is simply an accident of history.

If IPv4 had been designed with 64-bit addresses, or even 48-bit ones (like Ethernet MACs, which we still haven't run out of), then NAT probably would not have been invented, and we'd be using 'simple' (SPI) firewalls (see Cheswick 1994).

> […] but I wouldn't trust it as much as the security of a non-routable network.

Non-routable networks are not more secure than routable ones with SPI; at best the two are equal IMHO. Non-routable networks may actually be worse because of a false sense of security: all it may take is one end-point compromise and the enemy is one the other side of the moat.

Yes I agree with this but do note that in your gp you stated "every single personal device", not "half of all personal devices"

Even stateful firewalls don’t protect you from being hacked. Hacks occur when you run untrusted code on your machine. That untrusted code can easily bypass your stateful firewall by initiating a connection to a C&C server.

Thankfully, this is going away now with IPv6.

Unfortunately not. Most consumer and SOHO routers have reflexive ACLs enabled by default, and your average Joe doesn’t know or care to turn it off.

Oh, interesting, what is it exactly ?

Surprising that with over a year of discussions about this subject I only first hear of it ?

Would this be the reason why at least tens of millions of consumer routers don't have IPv6 firewalls (technically, opt-in firewalls, but you know how that goes...), and don't have their networks hacked ?

Wait, does it even work with UDP, which doesn't have a concept of "connection" ? (Especially IPv6 (no NAT) UDP ?)

I want to believe!

Well, IPv6 seems to be today (both in popularity and speed of adoption) where UTF-8 was about a decade ago. So, hopefully in a decade..?

NAT is a hack that only ever existed due to IP address exhaustion, and I’ve yet to find a good reason why congestion control and QoS handling in a router needs anything beyond what is already in the IP headers. SCTP’s flexibility is irrelevant since nobody uses it, arguably because of how much the Internet has ossified around TCP and UDP.

Hey, that's not true. People use it... in the telecom industry and everyone using WebRTC's DataChannel (SCTP over DTLS actually).

The protocol is probably mostly fine, but there are no quality library for using it in a general purpose way. Because of that, no one can really use the protocol to its full designed capabilities anyway (and the ossified network nodes don't help either).

It doesn't matter if SCTP has good features if no one is willing to implement quality libraries for it. The protocol exists for a while and only one general purpose library exists for it that's widely used. And it's not without a lot of flaws and limitations.

There are good reasons no one wants to invest in it, and I'm sure they did consider it.

I am sure there are even more implementations that I am not aware of.

* https://github.com/pion/sctp

* https://github.com/aiortc/aiortc/blob/main/src/aiortc/rtcsct...

* https://source.chromium.org/chromium/chromium/src/+/main:thi...

* https://github.com/sctplab/usrsctp

People don't make these decisions for technical reasons only. Career wise it is a bad choice to spend your time working on pre-existing technologies. You don't become a distinguished engineer by iterating on existing technologies. You become one by being the creator of something new.

I think QUIC is great and does a good job solving the problems it was designed to solve. It is disingenuous to pretend these decisions were made only for technical reasons.

3 of those are related to DataChannels in WebRTC, which at this point is baked into the standard and can't be replaced by another protocol. The SCTP in DataChannels is quite limited, that subset is reasonable to implement somehow.

Only the last one is really general purpose and has had a lot of security issues as well.

Fun fact: I do work on one of those implementations and with another one, and it's out of necessity rather than a career choice.

I know you understand libusrsctp Florent. I created Pion, I feel prety comfortable with SCTP and WebRTC in general as well.

RtcQuicTransport tried to replace SCTP and it didn't work. It would be possible to replace SCTP if something better was available. SCTP has lots of great stuff like FORWARD-TSN. QUIC didn't offer anything compelling over it. Also would come with a huge cost of making WebRTC larger and losing interop with all the existing clients.

libusrsctp has had security issues, but I don't think the protocol is the problem. The issue is C/C++. QUIC implementations are going to have the same class of bugs. Chrome/libwebrtc has plenty of security issues in other areas besides SCTP. Rust/Go doesn't fix everything, but one less thing to worry about at least.

If Google has a chance to use an industry standard or use their clout to create a new standard, you get one guess at what they're going to do.

Having a standard doesn't mean you're not allowed to innovate and create another one.

SCTP dates from RFC2960, first draft was published in 1999. It had enough time to get traction, and it didn't. Why would anyone build something new with it now, knowing that it doesn't answer some of the issues with the current Internet?

Even WebRTC's DataChannels were introduced at the IETF in 2012, that's 9 years ago (although ironically, the RFC just got published in January...).

Correct me if I'm wrong, but bypassing NAT, congestion control and QoS is also a benefit when you want to build things like P2P services where you want a direct connection between peers and full control over the connection itself. QUIC will help a lot with those use cases.

I'm happy whenever anyone brings up SCTP. Such a maligned protocol. Congestion control and QoS, however, are a loser's game. If you're running into realistic issues meeting demand due to statistical multiplexing breaking down to the point you must rely on caring about the internal state of traffic streams, you should have thrown more link hardware at the problem long ago. Many dumb pipes > fewer smarter pipes.

>NAT

Oh, didn't you know, IPv6 was going to solve everything. No more NAT. We're just going to assign everyone an IP at birth so people can continue to ignore the User-Agent/User distinction.

QoS has its uses, and you don't have to look any deeper than TCP/UDP headers for it to be good enough. It allows VOIP/IPTV services to continue working under DDoS conditions for example (ISP level).

IP TOS flag and TCI field in Ethernet header (802.1Q header) should be sufficient, without looking at TCP/UDP/SCTP headers.

NAT does not need anything more than port numbers or UDP cannot be used with it.

As for QoS going beyond port number, source IP and rate of packets asks for troubles.

I wonder : IPs are considered PI (heh). So does this mean that badly implemented QoS can end up violating RGPD ?