I have an already activated 3Gs iPhone running 4.0 with firmware 5.13.04 and the old boot 359.3, and I'm trying to jailbreak/unlock using Mac OS X. After much research I've found that I'm supposed to upgrade to 4.0.1 in order to use jailbreakme.com, then ultrasn0w for the unlock. I can't directly upgrade via iTunes, since Apple is no longer supporting 4.0.1 (instead it only wants me to upgrade to 4.1, which apparently cannot be jailbroken/unlocked on the 3Gs, as far as I know). I found the proper 4.0.1 ipsw file and downloaded it, but when trying to do the option/restore in iTunes, it won't let me. Apparently, iTunes tries to verify the file and refuses it since 4.0.1 is no longer supported. This site, http://www.saurik.com/id/12#howto, shows a way to bypass Apple's verification process by tricking iTunes into contacting Cydia instead. But I have a few questions that I'm hoping you can help me with. 1) Is there a better/easier way to upgrade to 4.0.1? 2) Saurik (on the site I linked) mentions that we need to find the host file, yet only gives the full path for Windows, and I can't seem to find the file on my Mac. Can anyone show me the full path? 3) Once I find it, I might need some help with "add the following entry to the bottom of the file: 184.108.40.206 gs.apple.com" if anyone has done this before? 4) Will this automatically save my SHSH blobs or do I need to manually do it? 5) If the phone was synced to the original owner's computer, and I use my computer to unlock it, will I still be able to connect to a 3rd or 4th computer to sync it once unlocked? Any and all answers are much appreciated! Thanks!