Echoart responds to or drops ICMP echo request packets based on a pre-defined sequence, and could be used to return crude ASCII art in response to pings from a Cisco router. It works by intercepting ICMP echo request packets and consulting a pattern template to determine whether or not to respond to a specific echo request. It then uses libnet to inject responses back into the network as necessary.
You can download it from the following link: https://packetstormsecurity.com/files/download/33369/echoart.tgz
Source: https://packetstormsecurity.com/files/33369/echoart.tgz.html