pingspray is a tool that generates network traffic for EMC (electromagnetic compatibility) tests. It can generate both random and periodic patterns of data as suggested in some EMC standards. It uses ICMP echo requests (ping) to generate traffic, and when it works as intended, it will generate traffic in both directions.
MasarLabs PatD is a daemon to ping or traceroute remote hosts, using IPv4 or IPv6 ICMP packets. It runs without root privileges, listening on a TCP local port for hosts to check. It uses a protocol simple to implement, so is useful in situations in which you cannot send native ICMP packets (for example, from a Java program). pat is a client you can use to talk to patd.