Algorithm for file updates in Python

Project Description 

In this project, we’re developing an algorithm to manage the access control system. The Python script reads IP addresses from an “allow list” file and a “remove list” file. It then removes any IP addresses found in both lists from the allow list and updates the allow list file with the remaining IP addresses.

# Specify the path to the allow list file
import_file = "/mnt/data/allow_list.txt"

# Specify the remove list (replace with actual IP addresses)
remove_list = ["192.168.0.1", "192.168.0.2"]  

# Step 1: Open the allow list file and read its contents
with open(import_file, 'r') as file:
    ip_addresses = file.read()

# Step 2: Convert the string of IP addresses into a list
ip_addresses_list = ip_addresses.split("\n")

# Step 3: Iterate through the remove list and remove matching IP addresses from the allow list
for element in remove_list:
    if element in ip_addresses_list:
        ip_addresses_list.remove(element)

# Step 4: Convert the updated list of IP addresses back into a single string
updated_ip_addresses = "\n".join(ip_addresses_list)

# Step 5: Open the allow list file in write mode and update it with the revised list of IP addresses
with open(import_file, 'w') as file:
    file.write(updated_ip_addresses)

Open the file that contains the allow list

import_file = "/mnt/data/allow_list.txt"
with open(import_file, 'r') as file:
    ip_addresses = file.read()

In this section, we use the open() function to open the allow list file in ‘read’ mode. We use a withstatement to work with the file object, which ensures that the file is closed automatically at the end of the block.

Read the file contents

ip_addresses = file.read()

Here, we read the entire content of the file using the read() method and store it in the ip_addresses variable.

Convert the string into a list

ip_addresses_list = ip_addresses.split("\n")

In this part, we convert the string of IP addresses into a list where each element is a separate IP address. We use the split() method with “\n” as the argument to split the string at every newline character.

Iterate through the remove list

remove_list = [...] # Specify the remove list here

for element in remove_list:
    # ...

In this section, we iterate over each IP address in the remove_list using a for loop where element is the loop variable holding individual IP addresses from the remove_list.

Remove IP addresses that are on the remove list 

if element in ip_addresses_list:
    ip_addresses_list.remove(element)

Here, we check if the current element from the remove_list is present in the ip_addresses_list. If it is found, we remove it using the remove() method. This method works as expected because there are no duplicate IP addresses in the list.

Update the file with the revised list of IP addresses

updated_ip_addresses = "\n".join(ip_addresses_list)
with open(import_file, 'w') as file:
    file.write(updated_ip_addresses)

In this section, we first join the elements of the updated IP addresses list into a single string separated by newline characters using the join() method. Next, we open the allow list file in ‘write’ mode and overwrite it with the updated list of IP addresses using the write() method.

Summary

We designed a Python algorithm to manage an allow list of IP addresses, updating it based on a specified remove list. The script sequentially performs these actions: reading the file contents into a string, converting the string into a list, iterating through the remove list to delete matching IP addresses from the allow list, and updating the file with the modified list. This process is crucial for maintaining a secure and current access control system for our company. It utilizes various Python built-in functions such as open(), read(), write(), split(), join(), and remove() to efficiently handle the allowed IP addresses. This demonstrates expertise in file manipulation and list operations in Python, which are key skills in cybersecurity and systems administration.