I mainly only use my Android WiFi Tether to connect my netbook when I'm traveling on vacations in the car, or at airports, etc. I'd rather not use public WiFi because then I'm relying 100% on my netbook's internal firewall for security, whereas when using WiFi tether on the Droid, I have installed my custom iptables firewall scripts into the Linux OS (the Droid is a router) and this firewall is much more secure because I control the scripts (I have similar scripts on my home Linux router), and you also have an extra layer of security in that the Droid router uses one-to-many NAT to give you a private IP address on your LAN sitting behind the firewall while the public (Verizon) IP address is on the other side of the firewall so nobody can directly ping you anyways. For this reason, when I need internet away from home, I use the 3G over the WiFi Droid router 100% of the time. But I probably only log less than 2 hours total time per month using tethering anyway, since most things I can directly do using the Droid itself when away from home. The netbook is only needed when I want a bigger screen (it has 1366x768), or when I need to use the Skype with video webcam. Any other thing I can do right on the Droid.
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