Jailbreaking Iphone 3G w OS 4.0.1

There are a lot of blogs that have partially correct tutorials for Jailbreaking Iphone 3G w IOS 4.0.1. Here's what worked for me. I started with the iphonehacks.com tutorial, but couldn't get past the first Redsn0w step. Then I found in an ihackintosh tutorial that you needed to have Redsn0w actually. Then, I found that once Jailbroken, I couldn't get Ultrasn0w to access Saurik's servers here in China. The issue turned out to be incorrect DNS settings here in CN (not sure if intentional on ISP/govt's part). This was nicely documented in this thread here on the Modmyi forum.

The process that worked for me was:

1. Copy latest Redsn0w from
2. Download firmware image (IPSW) for OS 4.0.1 (8A306)
3. Download firmware image (IPSW) for OS 4.0 (8A293)
4. Back up the iphone - this will allow restore of old programs, photos, movies, later.
5. Connect the iphone with iTunes, select the device (in left panel), hit shift-recover, and select the OS 4.0.1 image. This will take 5-10 mins to install new OS. Note that to activate the device the original SIM to which the iphone is locked was required. Actually, I'm not sure that this was really required, and in fact this whole step was not part of the ihackintosh tutorial. however, I think it could be useful for installing the OS 4.0.1 image. The ihackintosh tutorial appears to only install OS 4.0.
6. Next run Redsn0w and (this is important) select the 8A293 IPSW for OS 4.0, not the 4.0.1 version. This will modify and load the Jailbroken firmware on the phone, and in the end it is 4.0.1, not 4.0. Not sure if the previous 4.0.1 step was necessary for this.
7. Then try running Ultrasn0w from Cydia by entering selecting Manage tab, hitting Sources -> Edit -> Add and then enter http://repo666.ultrasn0w.com/. At this point, if running the iphone in China, Saurik's apt and cache servers will not be accessible, so a modification of the /etc/host file in the iphone directories is necessary. Get an iphone file browser or a command line editor that will let you access iphone files. Saurik suggests Iphone Browser, which is free and google-able. Go to /etc/ and download the host (not host-equiv) and edit it, such that the entire host file looks like
   

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting. Do not change this entry.
##
127.0.0.1 localhost
255.255.255.255 broadcasthost
::1 localhost
fe80::1%lo0 localhost

93.184.221.133 cache.saurik.com
74.208.10.24 apt.saurik.com




8. This should fix Cydia in China, and everything should work ok after this.