Test Cases and Examples of Actual Use
Examples from the tcpdump documentation:
To print all ftp traffic through internet gateway snup: (note that the
expression is quoted to prevent the shell from (mis-)interpreting the
parentheses):
tcpdump 'gateway snup and (port ftp or ftp-data)'
To print the start and end packets (the SYN and FIN packets) of each
TCP conversation that involves a non-local host.
tcpdump 'tcp[13] & 3 != 0 and not src and dst net localnet'