> By generating and
caching the Ethernet layer packet, we prevent the Linux
kernel from performing a routing lookup, an arpcache
lookup, and netfilter checks for every packet. An addi-
tional benefit of utilizing a raw socket for TCP SYN scans
is that, because no TCP session is established in the ker-
nel, upon receipt of a TCP SYN-ACK packet, the kernel
will automatically respond with a TCP RST packet, clos-
ing the connection