If you use a laptop as your home computer but take it on your travels too, it is important that the software firewall you use can distinguish whether you are at home or in a public network. Using file sharing at home allows you to stream music to your hi-fi or pictures to your TV, but clearly you want all inbound connections to your computer to be blocked when you join a public network on your travels. The test checked whether popular standalone and security-suite firewalls allow appropriate access in private networks but keep potential intruders out when connected to public networks – without requiring default settings to be changed. This basic check of firewall functionality was commissioned by a computer magazine. In future, we intend to conduct more detailed reviews of firewalls.