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Comment by jeromenerf | Hacker News Reader

Termux is a great project, may it be for cli lovers, hackers, road warriors ...

However, I have little trust in mobile devices nowadays and I don't feel safe copying private ssh/gpg/vpn/credentials data on them anymore. Planned obsolescence, theft risk, vendor/hardware/firmware issues, general feel of lack of control, ...

As a consequence, I tend to use my smartphone as anonymously as possible, mostly as a camera, an actual phone and 4G modem, tethering via usb/wifi to my laptop. It's simple, it feels safe and obviously it's not as practical.

I'd love postmarketos --or something similar-- to succeed, so I could leverage the privacy/backup strategies I have already set in place on laptops and servers that actually make me feel safe.

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Make a separate ssh key for your phone with restricted sftp-only access to a phone-specific backup directory on your server.

What's a good tutorial for restricting sftp access to a particular directory? (Assuming the same host supports ssh login, too.)

Assuming openssh-server, look for "internal-sftp" in sshd_config(5). And of course, also google a bit around that.

It's worth pointing out that this will preclude use of rsync and similar tools that require running a server on the remote machine. I'm not aware of robust alternatives so if anyone else knows one please tell me! (and I consider rsync-restricted shells and similar approaches a hack)

how about running OpenSSH inside docker with bind mounts?

are y'all talking about chroots?

I have a complete opposite feelings: mobile apps are actually sandboxed, modern phones have secure elements in hardware and the attack surface itself is pretty limited.

On the other hand, there's virtually no sandboxing on your laptop. As software developers, we pull random code from the internet all the time and it's generally trivial to steal every secret that your user has access to (https://xkcd.com/1200/)

Personally I'm not worried about baseband processor (or Intel ME) owning my device. I'm more worried about some random malware installing a keylogger and/or stealing my whole LastPass database. This would be virtually impossible on mobile, but is relatively trivial on laptop.

You sir, have very misplaced priorities.

I'd argue that both risk surfaces are large, not that the priorities are misplaced.

There's little of any electronics I trust much these days.

True there's no sandboxing by default on a typical linux desktop but I think the key difference between the linux distributions and Android security models is that your linux distribution is supposed to run trusted free software whereas your Android device is probably going to run some proprieatary untrusted apps.

That's why sandboxing is very necessary on Android and not so much on your linux box.

Now I agree you should sanbox everytime you can especially when linux is well capable of it, that's why I use firejail on my desktops so I get all the awesomeness of my favorite distributions AND strong sandboxing with real ease of use. https://firejail.wordpress.com/

One cool trick is to hook "sudo firecfg" in your package manager post operations so whenever you install new software it get sanboxed if a firejail profile is available (which is generally true). There may be a smarter way to do just that though?

That xkcd post makes a very good point indeed (that's why everybody should lock whenever afk, encrypt and use strong passwords of course) But I also think you should also worry about those backdoor issues: https://www.replicant.us/freedom-privacy-security-issues.php https://libreboot.org/faq.html#intel

I understand your feeling. I guess one can build "trust" or at least a somewhat "safe" feeling from simplicity, technical arguments, experience of a given evil ...

I "feel safe" running linux or openbsd on a "computer" given that I know only too well how flawed they can be. A mobile device could offer exactly the same feeling, and maybe better objective security characteristics, but unfortunately a "mobile device" doesn't seem to be defined as a "computer" you can single handedly operate but as a mix of short lived dependencies from hardware manufacturers to walled proprietary app stores through network carriers.

I don't dismiss the technical progress that is eventually happening in the mobile area but I think I'll pass as long as something as postmarketos offers what I feel is sustainable.

The apps are indeed sandboxed but who knows what everything below is doing. I trust more the maintainer of my distribution than whoever hacked an android rom to commercialize it.

Well rather than using it on a phone, look at the scenario of using this on a chromebook with android app support. Currently to run crouton to do linux development on a chromebook you have to run in the entire insecure developer mode where you're wide open to attack. Using termux on a chromebook under normal mode you can work without having to compromise your chromeos device's default security setup.

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