I’m planning to buy a router and modem and put OpenWrt on it for maximum control and privacy. While I could get a router with an integrated DSL modem, the previous tenants had cable internet so I’m not sure if the DSL connection even works and DSL internet is also more expensive (at least where I live). Fiber optic is not available. The problem is, there is apparently no open firmware for cable modems so I would have to buy a standalone router and a standalone cable modem. I would put OpenWrt on the router and use whatever proprietary firmware came with the modem.
So my question is:
Can a standalone modem that doesn’t do routing, spy on you?
If yes a rough explanation how would be appreciated.
It seems that modem and router are used interchangeably on the internet (probably because they are mostly combined) so it is really hard to find any information on modems. Here are both Wikipedia articles for reference:
https://en.wikipedia.org/wiki/Modem
https://en.wikipedia.org/wiki/Router_(computing)
What you think the modem can spy on by whom? Certainly not the ISP I suppose. They can already do it without the modem.
I don’t think ive heard about any privacy issues regarding modems. They convert your data into the Level 1 format so that it can be moved to the next hop. There isn’t really anything to spy on, and its very hardware dependent (hence no open source software that can standardize across each device). There might be open source modems out there, but your ISP probably doesn’t support them.
In an absolute sense, yes a modem can spy on you by hijacking requests and redirecting them to controlled locations. We use TLS to prevent this, even stronger with technologies like HSTS.
Does this happen in real life though? More then you think, but less of an impact then you think.
Some US providers will hijack DNS requests and redirect them to their own DNS servers, but this can be solved with DOH or DOT.
TLS interception is a thing but it requires the device you are using (phone, PC, tablet, laptop) to have a root certificate installed that the ISP also controls. Almost all browsers will only install root certificates from root certificate providers with good standing and have no quarm in untrusing the root certificate if things go badly.
Can it? Maybe. It’s not impossible; but it isn’t practical and most ISPs limit their shenanigans to grabbing your unencrypted DNS requests.
Will it? Probably no; aside from the previously mentioned DNS redirections; they’re not interested in most people’s packets, only in how many they deliver.
Should you care? I won’t tell you not to take precaution, but I do urge you to consider your threat model carefully and consider the tradeoffs. When Security & Privacy goes up, Convenience and Functionality WILL go down. Balance your needs. Don’t put yourself in a state of Privacy fatigue.
Are there easy fixes? Maybe. I think a VPN or using Tor would solve your concerns here anyways; it’s not required that your modem be running OSS that you can control. If you can achieve it; that’s still good for you; but it’s not something to be sweating if your modem isn’t capable and your invasive ISP is the only effective option.
First of all, the ISP controls cable modem firmware. They have all the settings and manage the device. You don’t get much control there.
As for your question, I’d say no, for 2 reasons. First, designing that capability is expensive and modems are built for cheap reliability. Second, any hardware to spy is more useful installed in a data center accessible to their user base. There is not much point installing unnecessary tech to one endpoint.
As for router, they are beefier CPU-wise. AT&T has in the past prevented users from changing DNS settings and that could lead to lots of tasty data. Deep packet inspection is becoming more prevalent in home routers as is integration with other technologies. (EERO devices for example).
Make sure to fire up a VPN or something when you need.
Thank you!
After posting this yesterday when lying in bed trying to sleep (i posted directly before going to bed) I thought of a similar reason:
Since (as far as i understood it) a modem is just a device that converts between 2 different types of internet signals, the ISP also needs one on their end to connect me to their data center. So it would be way easier for them to spy on their end of the cable (or signal, or whatever type of modem is used) than on my end, since there isn’t really much happening in between.
thanks for this, I was also in this situation, I got a xiaomi router and flashed OpenWRT on it, I then turned off the Wifi switch on the ISP router making it a modem only but I was still concerned about my internet data as it moves between my modem and their servers. your comment made it clearer
i should probably invest in that mullvad vpn now
