I have a roommate who is a network security engineer and I think he hacked our home network and now knows what sites I am visiting and what I am doing online. Although he is not stealing anything I think he must be playing with me. I read on the internet that if my router is a switch then it is not possible to snoop the home network, but my router is switch and I am not using a hub. How is it possible for him to know what websites I am seeing?. I have enabled the firewall, installed anti-virus, and secured the router login. Please let me know where to read and learn about it.
He's your roommate, so he probably has physical access to your machines and/or your networking equipment. Given that he's also a security engineer, there are probably dozens of ways that he could learn what sites you are visiting, from eavesdropping on the network communications, spyware on your machine, logs on your computer or your router, or a gazillion other possibilities.
There's probably not much point in speculating about what methods he is using, if indeed he is doing anything at all. Securing yourself against a roommate who is a security expert and you don't trust is ... well, it's basically a nightmare scenario for computer security. Defending against that is possible in theory, but in practice, not really realistic for the average person, and probably a major pain in the butt. Even if you somehow knew that he was hacking your machine/network and knew exactly what he was doing, and even if you were able to close off that particular hole, there would still be any number of other ways he could go after you, if he really wanted to play games with you.
If you really want to protect yourself as best as possible against that kind of threat model, here's what you could do to start: wipe your computer's hard drive, install a clean copy of the OS, install TrueCrypt and encrypt the entire hard drive using a hard-to-guess passphrase, turn off autorun, make sure when you leave your computer unattended you've powered down or done something that will require you to re-enter your TrueCrypt password to regain access, install HTTPS Everywhere, buy a secure VPN (one that encrypts everything that goes over the network, e.g., with SSL or IPSEC) and route all your communications through the VPN, and change your passwords on all your websites. It'll be a serious pain in the butt, and only you can say whether it's really worth it. If your roommate is just fooling around? Probably not worth the bother.
Probably the best way to deal with this is through social means, not technical means. In other words, either grin and bear it, or persuade your roommate to quit jerking your chain, or find a new roommate.
There are many ways to compromise such a network from the inside:
Of course, compromising your machine can't be fully ruled out either.
Well I guess, he had already access following information I can tell, because you said he can tell what websites you visited so far:
In order to prevent for accessing route admin page, please change your router admin's default password, don't setup your router with default password. And you don't want to setup wireless key as WPA/WPA2 networks which use pre-shared keys. PSK are easily crackable. If you prevent that, he can't able to access your wire-less connection.
And you can use VPN to secure your packets sniffing, you can buy VPN network online for it, it will cost about $40 for a year I guess. That will secure your data connection, he can't sniff your data even he is using same wireless connection at all unless he uses RAT on your machine.
And make sure you remove unwanted software and scan your OS with anti-virus program which is recently update virus definition if you don't want to reinstall newly fresh OS. Or newly fresh OS is recommended to install again on your machine if you can.
If you do above steps, I hope it can help you a lot and you can have peaceful life, harassment free from your roommate :)