If you have jailbroken your iPhone and have SSH installed it is a very good idea to change your default root password. The default root password for the iPhone 3G is “alpine” many people know this and if you are not careful you could get someone gaining access to your phone over your service providers’ data network or over a local wifi connection.
Once SSH is installed and active login to your phone using PuTTY. Download PuTTy here.
You will just need to specify your phone’s local wifi IP address and SSH as the connection method. When prompted, enter your username as : root and password as : alpine
Once you get a command line, type in the command “passwd” and press enter.
Enter your existing password of alpine, then specify your new root password. Be sure to keep this safe and secure! I found that after changing the root password on my phone I needed to restart it – close putty, then restart your iPhone.