A.4. ss

ss is a command-line utility that prints statistical information about sockets, allowing administrators to assess device performance over time. By default, ss lists open non-listening TCP sockets that have established connections, but a number of useful options are provided to help administrators filter out statistics about specific sockets.
One commonly used command is ss -tmpie, which displays all TCP sockets (t, internal TCP information (i), socket memory usage (m), processes using the socket (p), and detailed socket information (i).
Red Hat recommends ss over netstat in Red Hat Enterprise Linux 7.
ss is provided by the iproute package. For more information, see the man page:
$ man ss