Windows network utilities include the netstat command. This command is used to display active TCP connections and ports that computers are listening on, Ethernet statistics, routing tables, IPv4 statistics (for IP, ICMP, UDP protocols) and IPv6 statistics (for IPv6, ICMPv6 and UFP over IPv6 protocols). When launched without parameters, netstat displays active TCP connections.
Let's go to the command line. Click start> run> Enter cmd command. At the command prompt, enter the following command to display active connections on the screen:
To display all active TCP connections and all TCP and UDP ports that the computer is listening on, enter the following command:
To display active TCP connections and enable the display of the process ID (PID) for each connection, enter the command:
To display Ethernet statistics and statistics for all protocols, enter the following command:
Find out active ports and connections
In order to find out the active ports and connections, you need to type the command at the command prompt:
netstat -na | findstr "LISTENING"
If you do not set a filter findstr "LISTENING", then all active connections will be displayed, including in the "ESTABLISHED" state.
The ESTABLISHED state is the state of the connection that successfully passed the connection establishment procedure and over which no FIN packets were transmitted.
FIN (final, bit) - a flag that indicates the end of a connection (FIN bit used for connection termination).
You can find out which program the connection belongs to with the optional key "o".
netstat -nao | findstr "LISTENING"
This key will indicate the PID of the process. PID belonging to a specific program (process) can be found by typing the tasklist command.
In the Resource Monitor, open the “Network” tab, where you will see all processes with Internet activity, namely:
- process name (its executable file),
- ID (its identification number),
- average number of bytes per second received / sent since the program started.
You can control the process (pause / end) by right-clicking on the context menu on the executable file of the required process.
If the process (executable file) is unfamiliar to you, you will read information about it using the same context menu and the “Search the Internet” item.