This is where the process becomes complex. SelfishNet was abandoned by its original developer years ago; the last stable version (typically v1.2 or v1.3) predates the strict driver enforcement of Windows 10.
At its core, SelfishNet is a free ARP (Address Resolution Protocol) spoofing tool. Unlike complex enterprise solutions like QoS (Quality of Service) routers, SelfishNet operates directly from a single PC on the network. Its primary goal is deceptively simple: to cut off the internet connection of any selected device on your local Wi-Fi or Ethernet network, thereby making the connection "selfish" for the host machine. It achieves this by sending forged ARP packets to the target device and the router, convincing the router that the target device's IP address corresponds to the MAC address of the host PC. This effectively creates a man-in-the-middle (MITM) state, but instead of intercepting data, SelfishNet simply drops the packets, killing the target’s access. selfishnet windows 10
Once operational on Windows 10, the interface is brutally minimalist. It scans the local subnet (e.g., 192.168.1.0/24) and lists all connected devices by IP address, MAC address, and hostname (if resolvable). To block a device, the user simply checks a box next to the target. This is where the process becomes complex