Ok, so currently the hub can make outbound HTTP requests only. This is how LAN integrations are done for Foscam, Radio Thermostat, VLC Thing, just to name a few. There’s however much wider selection of 3-rd party LAN-connected devices with published (or reverse-engineered) API that use simple TCP socket protocol (a.k.a. ‘telnet’). Integration with these devices currently requires setting up a ‘bridge’ (typically a Linux server, e.g. Raspberry Pi) to translate HTTP requests from the hub to TCP socket messages.
The TCP socket feature has been requested numerous times by the community and was finally promised “before the end of the year” (that’s 2014). This promise has not materialized, unfortunately.