ho to downgrade 3gs w/o shsh

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Originally Posted by adnanali

just done 2 iphones both 3gs,both had been upgraded to v4.0.2
there was no previous jailbreak for these,so no backup of shsh.
this is very easy way to downgrade v4.0.2 to v4.0.1
you need latest itunes,get that from apple.
the v4.0.1 firmware:
Code:
http://www.iphone-hacks.com/download...6_Restore.ipsw
tinyumbrella get this from:
Code:
The Firmware Umbrella
we 1st need our shsh this is how its done.
edit your hosts file
i put
C:\Windows\system32\drivers\etc\hosts edit in notepad
add these 2 lines

127.0.0.1 gs.apple.com
74.208.105.171 gs.apple.com

click saveas,and save as hosts,
(vista and win7 users,need to right click notepad,and select "run as administrator")

start itunes,leave running,and ignore it for now.start tinyumbrella,(again if you using vista or win7 then right click "tinyumbrella" and select "run as adminastrator")
then plug in iphone.
tinyumbrella see iphone, +say its v4.0.2 if you tick the advanced
in the middle selectable field select "3gs iphone v4.0.1"
thats the trick,,,,,
click start TSS server
then save my shsh
it report saved ok,

now leave tinyumbrella tss server running,(in background)
disconnect iphone,click to bring itunes into view,
get iphone into DFU mode,/recovery mode,
if successful,it show black screen,plug it to computer,itunes see it in recovery mode,itunes ask you to restore.
hold down "shift" as you click "restore"
window pop up,point it to ur 4.0.1 firmware(the firmware you downloaded earlier).
if you doing 3gs iphone then its called
iPhone2,1_4.0.1_8A306_Restore.ipsw

sit back and let itunes do the rest,,,
then once done,post result plz

Lots of nonsense there, like two entries for the same host name etc.
Fact is you need shsh on Cydia or from Apple (only for current firmware) otherwise you cannot install ANY firmware on your iPhone.
(exception: old 3G phones or older with firmware before 4.0)
Anyone telling anything different hasn't understood how this works.