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Using 4G LTE wireless modems on a Raspberry Pi

jeffgeerling.com

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Re: Using 4G LTE wireless modems on a Raspberry Pi

#31

Post by geerlingguy »

Nextgrid wrote: post #28
geerlingguy wrote: post #2

This blog post has been quite the effort—coming into it I thought I'd just learn some new things, document a simple process, and be done. But along the way I probably spent 40 hours (and counting) trying to figure out the ins-and-outs of 4G LTE modems and Linux networking when it comes to these oddball devices. I hope some parts of this post help anyone else new to LTE networking in Linux, and maybe somebody can help…

> Why doesn't Quectel have any firmware downloads on their site? The telecoms industry in general is pretty shit and does a lot of anti-user nastiness like SIM locking or other arbitrary restrictions. It is not in the their best interests to let the user get too close to the inner workings of things. Security-wise it's also often terrible and security by obscurity is still very much the norm and would be threatened b…

Thanks for all the advice! I'll definitely give modemmanager a spin now; I had some initial trouble but it sounds like if I can get it working it will solve a lot of the pain points I had with the manual QMI setup.

Re: Using 4G LTE wireless modems on a Raspberry Pi

#32

Post by kube-system »

sneak wrote: post #29
kube-system wrote: post #15

Earlier quoted context omitted.

I feel like you'd probably get more predictable experience by using an always-on VPN configuration on your phone than a wifi hotspot.

iOS leaks requests around the VPN, sadly. I don't run an LTE base station and I don't have a jailbroken device, so I can't tell you how much, but I do know that with a VPN enabled and set to always, I get mobile-network IP DNS queries to my DNS server (not sent via VPN). iOS is not a privacy-focused OS. Having a discrete device means you can also connect multiple mobile devices via Wi-Fi on the same SIM, and do your…

Doesn’t it do the same on Wi-Fi? There’s a feature that intentionally does this too, “Wi-Fi assist”

Re: Using 4G LTE wireless modems on a Raspberry Pi

#33

Post by detaro »

kube-system wrote: post #32
sneak wrote: post #29

Earlier quoted context omitted.

iOS leaks requests around the VPN, sadly. I don't run an LTE base station and I don't have a jailbroken device, so I can't tell you how much, but I do know that with a VPN enabled and set to always, I get mobile-network IP DNS queries to my DNS server (not sent via VPN). iOS is not a privacy-focused OS. Having a discrete device means you can also connect multiple mobile devices via Wi-Fi on the same SIM, and do your…

Doesn’t it do the same on Wi-Fi? There’s a feature that intentionally does this too, “Wi-Fi assist”

Do what on Wi-Fi? How would a phone circumvent the VPN setup on the WLAN router it connects to?

Re: Using 4G LTE wireless modems on a Raspberry Pi

#34

Post by kube-system »

detaro wrote: post #33
kube-system wrote: post #32

Earlier quoted context omitted.

Doesn’t it do the same on Wi-Fi? There’s a feature that intentionally does this too, “Wi-Fi assist”

Do what on Wi-Fi? How would a phone circumvent the VPN setup on the WLAN router it connects to?

By sending the DNS request out of the other interface: the mobile network… which is the expected scenario in the case of a network interruption on the Wi-Fi interface.

But after rereading the parent comment, I think they could have a misconfiguration with their VPN. I just ran a few DNS leak tests with my WireGuard setup on iOS and they all go over the VPN to my personal resolver.

Or maybe only portions of the OS is leaking around the VPN (i.e not safari but system components).

Re: Using 4G LTE wireless modems on a Raspberry Pi

#35

Post by sneak »

kube-system wrote: post #34
detaro wrote: post #33

Earlier quoted context omitted.

Do what on Wi-Fi? How would a phone circumvent the VPN setup on the WLAN router it connects to?

By sending the DNS request out of the other interface: the mobile network… which is the expected scenario in the case of a network interruption on the Wi-Fi interface. But after rereading the parent comment, I think they could have a misconfiguration with their VPN. I just ran a few DNS leak tests with my WireGuard setup on iOS and they all go over the VPN to my personal resolver. Or maybe only portions of the OS is…

> As an aside: You should pull out the SIM from your mobile phone anyway

No, the idea is that you use your phone without a SIM card at all: no mobile network, wi-fi to the VPN router only.

Re: Using 4G LTE wireless modems on a Raspberry Pi

#38

Post by olyjohn »

walrus01 wrote: post #8

Note that where it says: > A mini PCI Express 4G LTE modem. I used a Quectel EC25-A, but there are some from Sierra Wireless I've heard recommended too. This is actually just a mini-pci-e adapter board that exposes the USB pins to the USB type A connector seen in the photo. It's not an actual pci-e bus device LTE modem. As shown in the example, it appears to the kernel as a USB device.

I was racking my brain trying to figure out how they did PCI over USB 2 and then just had the modem show up as a USB device. Maybe USB-C would have made some sense, sorta. Had no idea that the mini-pci-e connector could also just be used for USB.

Re: Using 4G LTE wireless modems on a Raspberry Pi

#39

Post by Handytinge »

sneak wrote: post #6

> A SIM card with a 4G data plan. I bought a SixFab SIM and used their monthly pay-as-you-go service for testing. You could pull out the SIM from your mobile phone (on most carriers at least) but that is a bit inconvenient as your phone won't get service until you put the SIM back in. You could also get a plan and SIM from any major carrier (e.g. AT&T, T-Mobile, Verizon in the USA)—though you have to make sure the ca…

> (This is why T-Mobile in the US is now blocking Apple's "Private Relay" encrypted service and are complaining loudly - it's costing them sniffing-data-resale revenue.)

I'm fairly sure this was shown to be false. From memory, they were shown only to be blocking it on their "family monitoring" opt in plan - i.e where they sniff and intercept at the behest of the owner. As far as I know, no US mobile carriers are blocking it beyond this. Do you have evidence of this?

> The carriers are monitoring all of your unencrypted DNS traffic (and your unencrypted SNI traffic that starts all of your TLS/SSL connections that says to which hostname you're connecting) and selling it, alongside your phone number and name.

You're probably right they're collecting it, but adding PII and selling it doesn't pass the Litmus test for me. Do you have any evidence or sources of this?

Whilst the advice you provide is sound, it appears to be built on unfounded falsehoods.

Re: Using 4G LTE wireless modems on a Raspberry Pi

#40

Post by rcarmo »

geerlingguy wrote: post #24
rcarmo wrote: post #19

Earlier quoted context omitted.

Yeah, things have become wildly fragmented since the "plain" 3G modem days, and there are no effective standards for USB multi-point devices (LTE made Ethernet emulation more popular, but weird pseudo-serials to configure them just became... weirder).

Heh, when I started researching and found that, yes, uart and AT commands are still the preferred way to interact with these modems, I was wondering if I had time-warped back to the 90s!

Yep. Amazing how the AT command reference I tweeted at you is still 50% valid since 2004 :D
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