That's why military might has been helpless against the recent stream of terrorist attacks around the globe. SYN flooding is an elegant attack that can be launched against any host on the Internet from practically anywhere else. When you type a URL into your Web browser and hit return, your computer sends out a SYN packet to the Web server you are trying to access. The server sends back an ACK packet, which says that your connection has been accepted. Finally, your computer sends back a second ACK, completing the three-way handshake.
Data then flows freely.
Come vent your spleen in Threads . Subscribe to PacketFlash, for Packet news. The attack program doesn't follow this sequence. Instead, it just sends out a stream of SYNs. The server sends back its ACK, never hears a response, and is left waiting.