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NAT Is the Enemy of Low Power Devices

blog.golioth.io

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Re: NAT Is the Enemy of Low Power Devices

#161

Post by vv_ »

glowing12131 wrote: post #88
hasheddan wrote: post #71

Earlier quoted context omitted.

Great pointer! My sibling post in this thread references a few other blog entries where we have detailed using eDRX and similar low power modes alongside Connection IDs. I agree that many devices don't need to be immediately responsive to cloud to device communication, and checking in for firmware updates on the order of days is acceptable in many cases. One way to get around this in cases where devices need to be fa…

Is "Non-IP Data Delivery" (basically SMS but for raw data packets, bound to a pre-defined application server) already a thing in practice? In theory, you get all the power saving that the cellular network stack has to offer without having to maintain a connection. While on protocol layer NIDD is almost handled like an SMS (paging, connectionless), it is not routed through a telephony core (and hence sloooow). The bas…

It has been heavily advertised, but its support is inconsistent. If you are deploying devices across multiple regions, you likely want them to function the same way everywhere.

Re: NAT Is the Enemy of Low Power Devices

#162

Post by vv_ »

bluGill wrote: post #115
shipp02 wrote: post #35

Earlier quoted context omitted.

What makes a separate cellular modem better than an internal cellular modem? Is it because software updates are available for the separate modems? I am evaluating some Nordic semiconductor parts for a project. They seem to have an internal modem but Nordic uses zephyr. Any thoughts?

cellular modems go nonfunctional/obsolete much faster than other systems. 3g is almost entirely gone worldwide. 4g is still around, but providers are already reducing how much their towers dedicate to it. The standards body is working on 6g, who knows when that will come and push out older stuff. If the case of my car I don't care - I have never found a use for the cellular connectivity it has (if any). However there…

Generally the modem would support EDGE/E-GPRS (2G) and 3G simultaniously. In Europe, EDGE/E-GPRS is still quite popular and unlikely to be sunsetted in the next 5 years. It is a pity that many manufacturers tightly integrated the modem into their PCB, instead of creating a separate "communication box" - especially as some use-cases have the budget for it.

Re: NAT Is the Enemy of Low Power Devices

#163

Post by vv_ »

jasonjayr wrote: post #128
vv_ wrote: post #20

The problem(-s) described in the blog post are really acute for IoT in general, especially if you want your device to run on batteries or you have a limited data budget. > Therefore, when you try to continue talking to the server over a previously established session, it will not recognize you. This means you’ll have to re-establish the session, which typically involves expensive cryptographic operations and sending…

> The blog post mentions Session IDs as a solution, but these require servers to be stateful, which can be challenging in most deployments. Doesn't this just move the 'state' into the operating system, or networking layer, in the form of an active TCP connection?

You can use Session Ticket's w/ UDP too.

Nevertheless, with modern cloud providers moving the state into the OS/Networking layer is still easier to scale. You don't need to write your own services to handle it.

Re: NAT Is the Enemy of Low Power Devices

#164

Post by vv_ »

bsder wrote: post #102
vv_ wrote: post #20

The problem(-s) described in the blog post are really acute for IoT in general, especially if you want your device to run on batteries or you have a limited data budget. > Therefore, when you try to continue talking to the server over a previously established session, it will not recognize you. This means you’ll have to re-establish the session, which typically involves expensive cryptographic operations and sending…

> It is often seen as more cost-effective to purchase a cellular modem with an internal MCU rather than a separate cellular modem and a host MCU to run the networking stack. This one isn't just cost--the compliance restrictions that the cellular carriers place on you are idiotic. The big one we bumped into is "must allow allow carrier initiated firmware updates with no restrictions on scheduling" which translates to…

Your experience is bizzare. Was it Verizon (or AT&T/T-Mobile) and did you use a Cat-1bis/Cat-M/NB-IoT or higher class modem?

Normally US carriers require Firmware-Over-The-Air (FOTA) capability for the modem firmware. This is not the case for deployments outside of the United States, to my knowledge.

It would be interesting to hear more about your story!

Re: NAT Is the Enemy of Low Power Devices

#165

Post by immibis »

bsder wrote: post #102
vv_ wrote: post #20

The problem(-s) described in the blog post are really acute for IoT in general, especially if you want your device to run on batteries or you have a limited data budget. > Therefore, when you try to continue talking to the server over a previously established session, it will not recognize you. This means you’ll have to re-establish the session, which typically involves expensive cryptographic operations and sending…

> It is often seen as more cost-effective to purchase a cellular modem with an internal MCU rather than a separate cellular modem and a host MCU to run the networking stack. This one isn't just cost--the compliance restrictions that the cellular carriers place on you are idiotic. The big one we bumped into is "must allow allow carrier initiated firmware updates with no restrictions on scheduling" which translates to…

Sounds like you need a more watertight contract and more lawyers.

Re: NAT Is the Enemy of Low Power Devices

#166

Post by bb88 »

kazinator wrote: post #160
bb88 wrote: post #97

Earlier quoted context omitted.

With CG-NAT this doesn't work. Multiple customers are sharing the same IP address, all of which are sitting behind a NAT. Further the internet gateway is a NAT sitting behind the CG-NAT. And if you prefer to use a nice Mesh WiFi router, well that's a third NAT layer. Common suggestions I've heard: "Use a VPN" I tried to buy a computer from Apple directly. They detected the VPN and wouldn't let me purchase it. I turne…

I don't have my own external IP address (even if dynamic) + I want my devices to be spontaneously contactable from the network without polling anything from the inside = does not compute

Right and that's what breaks the internet.

Re: NAT Is the Enemy of Low Power Devices

#167

Post by VagabundoP »

chgs wrote: post #154
VagabundoP wrote: post #150

Wasn't IPv6 suppose to solve all this? I don't understand why that stalled. Also considering the state of iot security its probably not a great idea to have everything accessible anyway. But that's a slightly different problem to solve.

It’s not going to solve a stateful firewall timing out. You try to continue a tcp session that’s timed out on my firewall and the packets will be dropped. This applies a fair amount t to me when I suspend my laptop, my ssh session will drop as both the server and the firewalls drop the session while it sits there peacefully. When it comes back the tcp packets get sent into the void. Meanwhile my WireGuard connection…

Why not let through all ipv6 traffic? It seems improbable that your device is going to get caught up in a ipv6 scan; the address space is too vast - I'm assuming here.

Just have relatively secure devices using ipv6 - not shipping with standard default admin passwords would nearly be enough if there aren't obvious vulnerabilities.

Re: NAT Is the Enemy of Low Power Devices

#168

Post by vv_ »

procaryote wrote: post #137
vv_ wrote: post #72

Earlier quoted context omitted.

The issue in IoT is that most people expect to be able to control their IoT (e.g. Smart Home) devices from outside of their network. This requires you to have a central server these devices communicate with or a similar deployment on-premises with a public IP address. I've always wondered how it is economically feasible to run these central services without a monthly subscription. If you stop selling devices you'll g…

Yeah, sadly, people care about convenience and not security. So you get things like this: https://www.malwarebytes.com/blog/news/2024/04/ring-agrees-t... and somehow they are still in business, and popular. If you do care about security, keeping your home-automation within your own control is probably the only sane path. Homeassistant and similar open source things like openhab are pretty good if a bit fiddly, and a…

> If you do care about security, keeping your home-automation within your own control is probably the only sane path.

It is also very expensive, so only a minority of informed users would select such a route. Not to mention that it is not trivial to setup.

To my knowledge the only company that has decent security practises is Ubiquiti.

What the article describes is actually fairly standard in the IoT industry. I'm surprised there have been so few lawsuits.

Re: NAT Is the Enemy of Low Power Devices

#169

Post by vv_ »

lxgr wrote: post #124
vv_ wrote: post #68

Earlier quoted context omitted.

Power Saving Mode (PSM), a power-saving mechanism in LTE, was specifically designed to address such issues. It allows the device to inform the eNB (base station) that it will be offline for a certain period while ensuring it periodically wakes up to perform a Tracking Area Update (TAU), preventing the loss of registration. This concept is similar to Session Tickets or Session IDs in (D)TLS—or at least, that’s how I l…

802.11 supports the same thing. A STA (client) can tell an AP that it'll be going away for some time, and the AP will queue all traffic for the STA until it actively reports back. Broadcast traffic can also be synchronized to particular intervals (but low power devices are usually not interested in that anyway for efficiency reasons).

I have very little experience with Wi-Fi, as the industry I worked in relied almost exclusively on cellular networks. However, I wonder how many Wi-Fi routers actually support this functionality in practice - as queing traffic means you need to cache it somewhere.

Re: NAT Is the Enemy of Low Power Devices

#170

Post by vv_ »

gwbas1c wrote: post #126
shipp02 wrote: post #35

Earlier quoted context omitted.

What makes a separate cellular modem better than an internal cellular modem? Is it because software updates are available for the separate modems? I am evaluating some Nordic semiconductor parts for a project. They seem to have an internal modem but Nordic uses zephyr. Any thoughts?

> What makes a separate cellular modem better than an internal cellular modem? The US 3G shutdown required some rather expensive and unexpected upgrades. Vendors signed long-term contracts with 3G providers, and then "someone" was on the hook, to replace something, when the 3G vendors terminated their contracts prematurely. The deeper the modem was integrated into a product, the harder it was to change. The shallower…

Car manufacturers should abandon developing their own entertainment systems and instead collaborate with Apple (CarPlay) and Google (Android Auto) to improve integration and support a wider range of use cases. Unfortunately, they seem to revive these efforts every 4-6 years (e.g. Mercedes Benz)

The only feature I need to control remotely in my car is preheating during winter—I wonder how they could achieve that without using cellular connectivity as paying a subscription for such a service would make it less attractive to me.

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