Methods and systems are disclosed for isolation of communications between a host computer system and one or more untrusted network destinations. An Internet isolation system may include a network, one or more host computer systems, a border firewall, an authorization device, and/or a proxy device. The Internet isolation system may be configured to implement network isolation between one or more untrusted network destinations, the one or more host computer systems, and/or the network. The network isolation may be implemented via one or more of a host-based firewall on each of the one or more host computer systems, the border firewall, the authorization device, the proxy device, an internal isolation firewall on each of the one or more host computer systems, and/or a segregation of a trusted memory space and an untrusted memory space on each of the one or more host computer systems.