gistfile1.txt

#!/usr/bin/env python3
import ipaddress, csv

# ◼ Adjust these file‐names/paths as needed
CIDR_FILE   = 'cidrs.tsv'
IP_FILE     = 'ips.txt'
OUTPUT_FILE = 'matched.tsv'

# 1) Load and parse your CIDRs
networks = []
with open(CIDR_FILE, newline='') as cf:
    reader = csv.reader(cf, delimiter='\t')
    for row in reader:
        if not row or row[0].startswith('#'):
            continue
        provider, cidr_str, desc = row
        network = ipaddress.ip_network(cidr_str)
        networks.append((network, row))

# Sort so that more‐specific (longer) prefixes get matched first
networks.sort(key=lambda x: x[0].prefixlen, reverse=True)

# 2) Open the output TSV and start matching
with open(OUTPUT_FILE, 'w', newline='') as outf:
    writer = csv.writer(outf, delimiter='\t')
    # ← optional header
    # writer.writerow(['IP','Provider','CIDR','Description'])

    with open(IP_FILE) as ipf:
        for line in ipf:
            ip_str = line.strip()
            if not ip_str:
                continue

            ip_addr = ipaddress.ip_address(ip_str)
            matched_row = None

            # find the first (most‐specific) network that contains this IP
            for network, row in networks:
                if ip_addr in network:
                    matched_row = row
                    break

            # write out: IP + (the full TSV row from cidrs.tsv)
            if matched_row:
                writer.writerow([ip_str] + matched_row)
            else:
                # no match → just output the IP (or you can write blanks)
                writer.writerow([ip_str])