Using Netstat

netstat

Use Netstat to show Network Connections on your Server

Basic Usage

> netstat -lp

Command Line Options

  • -l option shows listening ports
  • -p shows pids (process IDs) of listening processes
  • -n show numeric addresses, instead of symbolic host, port or user names

Notes on Different Command line Options

-p

  • Active Internet Connections (w/o servers)

-l

  • Active Internet Connections (only servers)

-r: Check routing table

-i: Display Interface statistics

This can be used if you are testing a slow connection or a connection
that is down

> netstat -i
Kernel Interface table
Iface       MTU Met   RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
eth1       1500 0         0      0      0 0             0      0      0      0 BMU
lo        16436 0      3800      0      0 0          3800      0      0      0 LRU
wlan1      1500 0    518088      0      0 0        304839      0      0      0 BMRU

This output shows (in the RX-OK column) that packets have been received
error-free on the lo (loopback) and wlan1 (wireless) interface,
however, no packets have been transferred on eth1, therefore either the
ethernet is down or unplugged. Also the TX-OK column shows that
packets have been transmitted on those interfaces as well.

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