When I check my IP at whatismyip.com (for example) I cab see my IP is 109.253.X.X. When I type netcfg at the phone's terminal I can see the line
rmnet0 UP 10.229.X.X
And indeed when I try out apps like "Droid IP Camera" it listens on 10.229.X.X (rmnet0 interface).
Is it a NAT configuration 3G uses? if so, how can I make apps like "Droid IP Camera" (this app is only given as an example) work over 3G?