Netstat
Gregg
My most frequently used netstat command with parameters for checking port (active internet) connections is:
$ netstat -tulpn
You can also pipe the output to grep to filter for specific ports or addresses.
Here is a brief listing of some of the many options:
$ netstat [options]
| Option | Action |
|---|---|
| -a | Display the state of all sockets, not just the active. |
| -c | Continuously display information, updating every second. |
| -i | Include network device statistics. |
| -n | Display all network addresses as numbers. |
| -o | Display additional information. |
| -r | Display routing tables. |
| -t | Display only the TCP sockets. |
| -u | Display only the UDP sockets. |
| -v | Print the netstat version number and exit. |
| -w | List only the raw sockets. |
| -x | Display only the Unix sockets. |