Netsphere was earth, the original earth that was without humans and the virus.
The exterminators are a program that downloads in to a place of the megastructure in order to eliminate an hacker. If the user had net terminal genes, this wouldn`t happen.
Safeguards: Unlike exterminators they are to search a net terminal gene berier and bring him or her into the netsphere. They also are in chare of cleansing the place of humans without that genes, including silicon life.
Silicon life: They are a race, a misture of machine and flesh that wants the extermination of everything humane. However, each one of them tries to achieve their own goals and see the net terminal gene carrier as something like God. A irony considering what they once were.