Toolbox Aid

August 9th, 2024 12:26 PM Mr. Q Categories: Command

Command: netstat

Used to display network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. It helps monitor network activity and diagnose network issues.

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Sample Command and Output:

$ netstat -a
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:22             0.0.0.0:*               LISTEN
tcp        0      0 192.168.1.10:22        93.184.216.34:49234     ESTABLISHED
udp        0      0 0.0.0.0:68             0.0.0.0:*                          
udp        0      0 192.168.1.10:123       0.0.0.0:*                          

Description:

• netstat -a: Displays all active network connections and listening ports. Includes details such as protocol (Proto), local and foreign addresses, and connection state.

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Additional Commands and Sample Outputs:

• netstat -r: Display the routing table. Sample Command and Output:

  $ netstat -r
  Kernel IP routing table
  Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
  192.168.1.0     *               255.255.255.0   U     0      0        0 eth0
  default         192.168.1.1     0.0.0.0         UG    100    0        0 eth0

Description:

• netstat -r: Shows the routing table. It includes the destination, gateway, netmask, and interface for each route.
• netstat -i: Display network interface statistics. Sample Command and Output:

  $ netstat -i
  Kernel Interface table
  Iface   MTU  RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
  eth0   1500  1234      0      0      0   567      0      0      0 BMRU
  lo     65536  123      0      0      0    123      0      0      0 LRU

Description:

• netstat -i: Displays statistics for each network interface, including the number of packets received and transmitted, errors, and drops.
• netstat -s: Display network statistics by protocol. Sample Command and Output:

  $ netstat -s
  Ip:
      1234 total packets received
      567 packets forwarded
      12 packets not forwardable
      7898 total packets sent
  Icmp:
      123 ICMP messages received
      34 ICMP messages sent

Description:

• netstat -s: Provides statistics for various network protocols, such as IP and ICMP, including the number of packets received and sent.

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This command provides a comprehensive view of the system’s network activity, interfaces, and routing information.