Rabbit RCM Server (UDP/RC4)
Like custom AVRs or Arduinos, Rabbit RCMs (now Digi-Keys) are 8-bit microprocessors (outperforming some 32-bits) stacked with mostly anything. The RCM2200 comes with 10Base-T Ethernet, 26 I/O parallel lines, 128k RAM, and 256k flash enough for doing some heavier processing (encryption etc.) on real-time sensor data and sending to a remote client. Nowadays, series RCM6XXX would be good option. The RCM module runs a server on customized port which collects data (temperature) and awaits a connection by the JAVA client. Upon authentication, the readout stream is secured with RC4 and sent over UDP back to the client. The code dates to 2003 and 2007 when I was using proprietary Dynamic C compiler and work license.