Call a professional - do not attempt to deal with this yourself. Keep your dogs away from it. They don't chase and are not actively aggressive, only defensive, so keep your distance and the snake is not a danger. Look up "snake removal" along with your city in a search engine and call the number. They may charge a small fee for the service, but it is worth it to have it handled absolutely and safely.
What ever you do, don't try to deal with it yourself. Contact a local professional. Maybe in your phone book or on the Internet. For now I'd say if its under your front porch, let your dogs out out back of your house. Hope I helped :)