If -s is not given do a dummy connect to get outgoing ip,

If -s is not given do a dummy connect to get outgoing ip,
unconditionally try to bind to this ip and get a source port for udp
this way, like traceroute6 is doing.  This means you can no longer
traceroute from IPs not present on the system. (There are probably
better tools if you want to send traffic from spoofed IPs.)
OK benno@