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Automation & scripting

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Automation & scripting easy

How to Write an IP Block List to hosts.deny in Python

This Python script validates a list of IP addresses and CIDR ranges, then writes them to a hosts.deny file to block connections at the TCP wrapper level.

hosts.deny ip-block ipaddress
Python 
from ipaddress import ip_network

def write_hosts_deny(ip_list, output_file="hosts.deny"):
    with open(output_file, "w") as f:
        for ip in ip_list:
            try:
                ip_network(ip)
                f.write(f"ALL: {ip}\n")
            except ValueError:
                continue
    print(f"Written…
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