Common Network Commands: Netstat

-

Netstat Command Overview

    Netstat (short for "network statistics") is a command-line tool available on various operating systems, including Windows, Linux, and macOS. It provides comprehensive information about the network connections, routing tables, interface statistics, masquerade connections, and multicast memberships.

Key Features

1. Active Connections: Displays the current active connections to and from your computer, including the protocol (TCP or UDP), local and remote addresses, and the connection state.

2. Listening Ports: Shows which ports are actively listening for incoming connections, useful for identifying open ports and services running on the machine.

3. Routing Tables: Provides information on the routing paths that data packets take to reach a destination, including the destination network, gateway, and interface.

4. Network Interface Statistics: Displays statistics about the network interfaces, including the number of packets transmitted and received, errors, and collisions.

5. Multicast Memberships: Lists the multicast group memberships for the host.

Common Option

The netstat command has several options that allow you to customize its output. Below are some commonly used options:

-a: Displays all active connections and listening ports.

-t: Shows only TCP connections.

-u: Displays only UDP connections.

-n: Shows numerical addresses instead of resolving hostnames.

-p: Displays the process ID (PID) and name of the program to which each socket belongs (available on Unix/Linux).

-r: Displays the routing table.

-i: Shows a list of network interfaces and their statistics.

-s: Displays summary statistics for each protocol (TCP, UDP, ICMP, etc.).

-c: Continuously displays updates every second (available on Linux).

Usage Examples

1. Display All Active Connections and Listening Ports:  

   netstat -a

2. Show TCP Connections Only:  

   netstat -t

3. Show UDP Connections Only:  

   netstat -u

4. Show Connections with Numerical Addresses:  

   netstat -n

5. Display the Routing Table:  

   netstat -r

6. Display Network Interface Statistics:  

   netstat -i

7. Show Summary Statistics for Each Protocol:  

   netstat -s

8. Show Active Connections with Process Information (Linux):  

   netstat -p

9. Continuously Update the Display:  

   netstat -c

Interpreting Output

The output of netstat can vary based on the options used, but here’s a general structure for TCP connections:


```

Proto Recv-Q Send-Q Local Address           Foreign Address         State  

TCP   0      0      192.168.1.5:80         203.0.113.10:12345     ESTABLISHED  

```


- Proto: The protocol used (TCP/UDP).

- Recv-Q: The number of bytes received and not yet read.

- Send-Q: The number of bytes waiting to be sent.

- Local Address: The IP address and port number of the local machine.

- Foreign Address: The IP address and port number of the remote machine.

- State: The state of the connection (e.g., ESTABLISHED, LISTENING, TIME_WAIT).

Use Cases

1. Troubleshooting Network Issues: netstat can help diagnose network problems by revealing open connections, listening ports, and network interface statistics.

2. Security Auditing: By examining active connections and open ports, administrators can identify unauthorized access or services running on the system.

3. Performance Monitoring: Network performance can be assessed by reviewing interface statistics and connection states.

Netstat is a powerful tool for network diagnostics and monitoring. Understanding how to effectively use it can aid in troubleshooting connectivity issues, auditing network security, and managing system performance.


Comments

Post a Comment

Popular posts from this blog

Common Network Commands: Ping

-
Ping Command Overview The `ping` command is a fundamental utility used in network diagnostics. It checks the reachability of a host on an Internet Protocol (IP) network and measures the round-trip time for messages sent from the originating host to a destination computer. The command uses the Internet Control Message Protocol (ICMP) to send echo request packets and listens for echo replies. Origin and Development The `ping` command was developed in 1983 by Mike Muuss as a diagnostic tool for the ARPANET. Since then, it has become a standard utility available on most operating systems, including Linux, Windows, and macOS, making it an essential tool for network administrators and users. Basic Functionality The `ping` command serves several functions: - Tests connectivity to a specified host. - Measures the time taken for packets to travel to the destination and back. - Provides statistics about packet loss and round-trip time. Key Command Syntax 1. Basic Syntax:    ```    ping [options]
Read more

Common Network Commands: Route

-
Route Command Overview The route command is a part of the older net-tools package used in Linux systems for viewing and manipulating the IP routing table. It provides information about how packets are routed through the network and allows for the addition, deletion, and modification of routes. Origin and Development Historically, the route command has been a primary tool for managing network routing in Linux. However, it has largely been replaced by the ip command from the iproute2 package, which offers more advanced features and capabilities. Despite this, route is still commonly used in many Linux distributions for its simplicity and familiarity. Basic Functionality The route command serves several functions: - Displays the current routing table entries. - Shows destination networks, gateways, and associated interfaces. - Allows for the addition, deletion, and modification of routes. Key Command Syntax 1. Display Routing Table:    ```    route -n    ```    The -n option prevents DNS
Read more

John The Ripper

-
John the Ripper  Is one of the most well known, well-loved and versatile hash cracking tools out there. It combines a fast cracking speed, with an extraordinary range of compatible hash types. This room will assume no previous knowledge, so we must first cover some basic terms and concepts before we move into practical hash cracking. A hash is a way of taking a piece of data of any length and  representing it in another form that is a fixed length. This masks the original value of the data. This is done by running the original data through a hashing algorithm. There are many popular hashing algorithms, such as MD4,MD5, SHA1 and NTLM. Lets try and show this with an example: If we take "polo", a string of 4 characters- and run it through an MD5 hashing algorithm, we end up with an output of: b53759f3ce692de7aff1b5779d3964da a standard 32 character MD5 hash. Likewise, if we take "polomints", a string of 9 characters- and run it through the same MD5 hashing algorithm, w
Read more