can you recommend any (opensource or trusted) android apps to check who’s using your wifi? or any cmd prompt code to search on the desktop?
a small doubt: can anyone hack your computer through WiFi? If so, How to prevent that (or) How to take measures after you think you been hacked?
That’s the point of mentioning the physical access. Yes it’s easier to get at ‘physically’ in that it allows you to reach it through walls, but, if physical access WAS obtained what protections do you have in place for a lan jack? It’s possible to use 802.1x auth or such but for most home users it’s just a case of plug in a cable and you’re part of the network.
Again someone is going to have to break into your house to accomplish this. You have much bigger problems if that happens.
The more realistic approach would be people sitting outside of your house trying to brute force your wireless password, which only works on networks with default or weak passwords.
The odds of someone breaking into your house to use your net are virtually zero. On the other hand people sitting in their cars to high jack wireless happen all the time. Anyone can do it they just need to be in proximity to your house and you’ll never know it’s happening.
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Assume physical access, someone walks in and has 5 minutes out of sight. A decent wpa2 password would take an extraordinary long time to brute force. Something like above gets deployed and allows remote access in seconds on an unprotected lan. As noted in another comment sketchy IOT gear is a threat people install willingly. The old test of leaving a loaded USB in the parking lot catches more people than is reasonable. Don’t assume a physical door is going to stop someone more than a proper technical barrier.