My neighbour was looking to expand his network, and I have a couple of old TL-PA551 which I lent him so he could add an access point at the back of his house.

We were trying to get it all working and kept getting an odd IP address on his computer from DHCP.

Lots of head scratching until I realised that the IP address was being issued by my router in my house.

The TL-PA551s had connected to my Powerline network in a different house.

I'm now intrigued at the range this could be used over, and also what security measures I should consider. Is the Powerline network name essentially an encryption key? How secure is it? If someone on the same power phase or circuit as me knows the key would they be able to access my network just by plugging in a powerline device and configuring it with the same network name? Are there tools for discovering other powerline networks that can be accessed?