Does iPhone 5 have a terminal? I'm new to iPhones and Mac, but I pretty ok with Linux. I think I could solve some of my networking issues, if I could just get into a bash shell, but I haven't been able to locate a shell.

Is there a default shell for iPhone 5? if so, where is it? 

If not, is there a preferable terminal emulator in the App Store?
iPhone does have a shell, bash to be specific, but you can't access the shell without jailbreaking, and any 'shell' app from the App Store won't have the ability to interact with the device in any reasonable manner necessary for fixing network problems.