## Netstat allows you to check the state of ports on the local host. ### On Windows - `-a` displays all connections (active [[TCP]] and UDP connections plus ports in the listening state). - `-o` shows the Process ID (PID) number that has opened the port. - `-b` shows the process name that has opened the port. - `-n` displays ports and addresses in numerical format. Skipping name resolution speeds up each query. - `-s` shows per protocol statistics (such as packets received, errors, discards, unknown requests, port requests, failed connections, and so on). - `-p` proto displays connections by protocol ([[TCP]] or UDP or TCPv6/UDPv6). When used with `-s`, this switch can also filter the statistics shown by IP, IPv6, ICMP, and ICMPv6. - `-r` shows the routing table. - `-e` displays Ethernet statistics. --- ### On Linux - `‑t` for [[TCP]] Internet connections - `‑u` for UDP Internet connections - `‑w` for raw connections - `‑x` UNIX sockets/local server ports - `-a` includes ports in the listening state in the output. `-l` shows only ports in the listening state (omits established connections). - `-p` shows the Process ID (PID) number that has opened the port (similar to `-o` on Windows). - `-r` shows the routing table. - `-s` displays protocol statistics (as in Windows). - `-i` displays interface statistics (similar to `-e` on Windows). - `-e` displays extra information. - `-c` sets output to update continuously. ### example For example, the following command shows Internet connections ([[TCP]] and UDP) only: `netstat ‑tu`