Using the Dig Command in Python

 Digest is quite a simple command-line network utility that lets a user perform DNS queries, and gain basic information about certain domain names or addresses and other related DNS details. For this purpose, the integration of this functionality in Python will be advantageous for the developers as well as network administrator who need DNS lookups or overall network diagnostics.

In this article, we will also take a look at how to execute the system command in Python, how to use the subprocess to run the dig command and an example code test.

Running System Commands in Python

There are a number of ways in Python to execute some commands that have system level functionality from with the code. The subprocess module seems to be a very well known and stable, and what is more it enables to create new processes, communicate with their standard input/output/error and gather their exit codes. This makes it optimal for running external commands such as dig; or for capturing the responses of such commands programmatically.

Using the subprocess Module to Execute dig

In this section let us use the subprocess module to execute dig by entering the following command below.

subprocess module of Python provides an interface to create new process and new programs in an Python program. When using dig in Python that is easy done with subprocess.run() or subprocess.Popen(). Therefore, one can perform the DNS resolution and save the outcomes in either of the python environment or to be precise either in FP3 or in FP5.

Here’s a breakdown of how to use subprocess to execute dig:

subprocess.run(): This function executes the command and heads for its termination then it issues the output in a CompletedProcess form.

subprocess.Popen(): It runs the command in the background since this function is more flexible in the execution process since one can monitor the command’s input/output.

Example Code Snippet

Let’s write a Python script that executes the dig command using the subprocess.run() function.

Python

import subprocess

# Domain to be queried
domain = "example.com"

# Execute the dig command
try:
    result = subprocess.run(["dig", domain], capture_output=True, text=True)
    
    # Check if the command was executed successfully
    if result.returncode == 0:
        # Print the output from dig command
        print("Dig Command Output:")
        print(result.stdout)
    else:
        print(f"Error occurred: {result.stderr}")

except FileNotFoundError:
    print("Error: dig command not found. Make sure it is installed and available in the system's PATH.")

Explanation:

1. subprocess.run(): We use this function to start the dig command which we use in this tutorial. It receives the command and its arguments as a list (Here the domain form a list with dig in this case).
2. capture_output=True: This flag records two important outputs of the command: the ordinary output or the normal output on the terminal and the error message usually shown at the terminal.
3. text=True: Transforms the result made by the mood detector into string format.
4. result.stdout: This saves the run and result of the given command.
5. result.stderr: This records the output if there is an error occurred during running the code.

The script will print the DNS information for the domain example.com, retrieved using the dig command.

Output

When you run the above Python script, you will see the output of the dig command printed in the terminal. For example, querying example.com might give the following result:

Output

This shows the DNS query for example.com, including its IP address and other relevant DNS information.

Conclusion

When integrating the dig command into Python using the subprocess module you can automate DNS queries and take benefit from effective use of DNS diagnostics in your python scripts. It can be especially beneficial when it comes to network automation, work diagnosis or if a packet captures DNS data for analyzing purposes.