+setuid root, so that it can create an ICMP socket. Root privileges
+are disavowed shortly after startup (just after connecting to the
+X server and reading the resource database) so this is \fIbelieved\fP
+to be a safe thing to do, but it is usually recommended that you
+have as few setuid programs around as possible, on general principles.
+.EX
+chown root.root sonar
+chmod u+s sonar
+.EE
+In ping-mode, the display is a logarithmic scale, calibrated so that the
+three rings represent ping times of approximately 2.5, 70 and 2,000
+milliseconds respectively.
+
+This means that if any the hosts you are pinging take longer than 2
+seconds to respond, they won't show up; and if you are pinging several
+hosts with very fast response times, they will all appear close to the
+center of the screen (making their names hard to read.)