Netstat – A command to display Network Statistics.
Netstat is a command which is very useful for network statistics, we can view all open network ports of the system weather it is in Listening or Established mode.
|-a||Displays all connections and listening ports.|
|-b||Displays the executable involved in creating each connection or listening port. In some cases well-known executables host multiple independent components, and in these cases the sequence of components involved in creating the connection or listening port is displayed. In this case the executable name is in  at the bottom, on top is the component it called, and so forth until TCP/IP was reached. Note that this option can be time-consuming and will fail unless you have sufficient permissions.|
|-e||Displays Ethernet statistics. This may be combined with the -s option.|
|-f||Displays Fully Qualified Domain Names (FQDN) for foreign addresses.|
|-n||Displays addresses and port numbers in numerical form.|
|-o||Displays the owning process ID associated with each connection.|
|-p proto||Shows connections for the protocol specified by proto; proto may be any of: TCP, UDP, TCPv6, or UDPv6. If used with the -s option to display per-protocol statistics, proto may be any of: IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, or UDPv6.|
|-r||Displays the routing table.|
|-s||Displays per-protocol statistics. By default, statistics are shown for IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, and UDPv6; the -p option may be used to specify a subset of the default.|
|-t||Displays the current connection offload state.|
|interval||Redisplays selected statistics, pausing interval seconds between each display. Press CTRL+C to stop redisplaying statistics. If omitted, netstat will print the current configuration information once.|
This command will display all connection and listening port.
This command will display all connection in numerical form (without resolving IP address to name).
netstat -a -n
Below command will display statistics.
TCP Statistics for IPv4
TCP Statistics for IPv6
UDP Statistics for IPv4
UDP Statistics for IPv6