pfSense

In infrastructure mode, pfsense automatically connects to a open wifi network. Quote from the SSID field description on my WAN interface (a wifi card):

Note: Only required in Access Point mode. If left blank in Ad-hoc or Infrastructure mode, this interface will connect to any available SSID

In my opinion this is a security problem: Suddenly all my traffic flows over a foreign wifi network where maybe e.g. the owner is listening. I really do not like this behaviour and I think it shouldn't be this way. Note that I configured my WAN interface using the initial interface assignment wizard (on the console on the first pfsense boot) where the options are limited and I couldn't set an SSID to restrict the connection to one specific SSID!