A firewall is a something that exists as software but also in cyberspace used to keep control over what files are allowed and what is refused or quarintined.
In cyberspace firewalls take the Form of Humanoid Security Officers which spend most of their time keeping hostile programs from entering an area of cyberspace. Neuron being Cyberspace Incarnate is the equivilant of God in this dimension. Firewall security officers just ignore him since he is the system.
UGI Cyberspace Firewall are among the most sophisticated and advanced in the time, due to their technological level, however they do have the distinct difference that they do not lurk out and search they activate when they choose to and find a threat. They are extremely fast learning and extremely adaptive once an attack happens to them, they learn, and it is impossible to successfully attack them the same way.