Many friends who travel frequently often encounter this strange phenomenon, that is, in some places where there are many laptops, such as cafes and airports, there will be a special "free public wireless" network. They are usually the same as standard Wi-Fi. The base station structure is different, but an Ad Hoc network established by computers.
Security personnel warn that such ad hoc networks may be traps set by hackers, and connecting to such strange networks may cause various security problems.
This problem is more common on Windows xp. The controlled computer may be controlled to create its own Ad Hoc network (the name is usually confusing, such as linksys, t-mobile, default, etc.) to attract other users.