Seattle-based Lockdown Networks, a provider of Network Access Control (NAC) hardware used for enterprise IT security, said today that it has upgraded the firm's Lockdown Enforcer software. The software, which is used to control which PCs are allowed on corporate networks, now also supports two new security techniques. Lockdown said the firm's security appliances now provides support for VLAN and IP subnet quarantine capabilities; the firm said the additions will allow its NAC capabilities to be deployed in as little as one hour. The firm's new IP subnet quarantine mode (ISQ) uses DHCP relay to present multiple instances of DHCP servers to a network; the mode essentially hides the presence of other servers from non-authorized devices. Lockdown sells its network access control appliances starting at $24,995.