Yes, there is a utility that will allow you to shut down your system through software commands. It requires that you have root on your install(you would have been asked during install and if you didn't say yes, you will need to format the drive, reinstall and choose yes).
Reboot menu (needs root)
play.google.com
The first time you run it you will be asked for root access, deny the first time, then go into the root management menu and allow. This is because if you allow on the first instance Reboot will shut down the system before the "Allow" setting is saved in system settings(it's that fast). It's a little tricky and I can walk you through it if you'd like.
Additionally, you should use a firewall as well.
[ROOT] AFWall+ is a front-end application for the powerful iptables firewall.
play.google.com
Again, requires root, but it's an excellent way to protect yourself and your Android system from a lot of harm. I would recommend the paid version as it's worth every penny and supporting the dev is always a positive thing, but you don't have too. The only differences between the two are the Gold Shield Icon instead of the Silver Shield Icon.
[ROOT] AFWall+ is a front-end application for the powerful iptables firewall.
play.google.com