... 55 2 55 8acquiring, 55 2command syntax, 55 4exercise in using, 55 7 55 8IP spoofing with, 55 5 55 6options available in, 55 3 55 4port scanning with, 55 3, 55 4 55 5testing DNS connectivity with, 55 7testing ... blocking, 53 54 registered, 50 , 51 52 scanning with Gnome Service Scan (GSS),129, 131, 132scanning with Netcat, 55 2 55 3, 55 4 55 5, 55 7 55 8scanning with Remote Nmap, 149– 151 scanning with Telnet, 55 1 55 2 source, ... forgers, 55 8 56 2packet generators, testing firewalls with, 55 1, 55 8 56 2packet mangling, 456 packet redirection, firewalls and, 448packet rules, 450 , 451 anti-spoofing rules, 479checking, 54 5, 54 8,...