There are bad guys (and girls)out there! Q:What can a“bad guy”do? A:A lot!See section 1.6 eavesdrop:intercept messages actively insert messages into connection impersonation:can fake (spoof)source address in packet(or any field in packet) ·hijacking:“take over”ongoing connection by removing sender or receiver,inserting himself in place denial of service:prevent service from being used by others(e.g.,by overloading resources) Security 8-7 There are bad guys (and girls) out there! Q: What can a “bad guy” do? A: A lot! See section 1.6 • eavesdrop: intercept messages • actively insert messages into connection • impersonation: can fake (spoof) source address in packet (or any field in packet) • hijacking: “take over” ongoing connection by removing sender or receiver, inserting himself in place • denial of service: prevent service from being used by others (e.g., by overloading resources) Security 8-7