I'm sorry, the first line of the previous e-mail is wrong! It was: I have tried: "tcpdump icmp > tcpdump_results2" and "tcpdump icmp > tcpdump_results3". it should have been: I have tried: "tcpdump icmp > tcpdump_results2" and "tcpdump icmp |grep request > tcpdump_results3". Nuno Faria