The Common Open Research Emulator (CORE) is a tool for emulating networks on one or more machines. You can connect these emulated networks to live networks. CORE consists of a GUI for drawing topologies of lightweight virtual machines, and Python modules for scripting network emulation.
Send steganographed text messages to mtr with fake hops in the network
Steganoroute is a tool to send steganographed text messages to another computer over the network. The receiver must make a traceroute to the sender using the mtr program (and pressing 'd' once to switch the display mode to the continuous graph). This tool, the sender, creates several fake hops and makes them answer the ICMP packets (or not) to write the letters one by one on the mtr client screen.