Extract IP Address from File using Python

Last Updated : 19 Jan, 2026

An IPv4 address is a 32‑bit numerical label used to identify a device on a network. It is written as four decimal numbers (each between 0 and 255) separated by periods (dots). Example of IPs: 192.168.1.1 , 8.8.8.8 , 127.0.0.1 

Below are Python examples that demonstrate how to extract all IPs and only valid IPv4 addresses from a file using regular expressions.

1. Extracting All IP Addresses

This method extracts any IP-like pattern, even if it is not valid (e.g., 999.999.999.999). Below is the sample file (test.txt) used in this example:

ip
test.txt
Python 
import re

with open('test.txt', 'r') as fh:
    lines = fh.readlines()
pattern = re.compile(r'(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})')

ip_list = []
for line in lines:
    match = pattern.search(line)
    if match:
        ip_list.append(match.group())
print(ip_list)

Output

['192.168.4.164', '69.168.4.226', '32.89.31.14', '67.168.3.227']

Explanation:

  • pattern = re.compile(...): Define pattern to match IPv4 addresses.
  • ip_list = []: Initialize list for IPs.
  • for line in lines... Loop lines, search IPs, append matches.

2. Extracting Only Valid IP Addresses

To extract only valid IPv4 addresses (0-255), we need a stricter regex pattern. Rules for a Valid IPv4 Address are given below:

  • Each number must be between 0 and 255
  • Must contain exactly 4 numbers separated by dots

Regex for Valid IP Addresses

((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}
(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)

Explanation:

  • 25[0-5]: Matches 250–255
  • 2[0-4][0-9]: Matches 200–249
  • [01]?[0-9][0-9]?: Matches 0–199 (with optional leading 0 or 1)
  • {3}: First three numbers followed by dots

Below is the sample file (test2.txt) used in this article.

test2.txt 
Python 
import re

with open('test2.txt', 'r') as fh:
    lines = fh.readlines()

pattern = re.compile(r'((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}'r'(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)')

valid_ips = []
invalid_ips = []

for line in lines:
    line = line.strip()
    if pattern.fullmatch(line):
        valid_ips.append(line)
    else:
        invalid_ips.append(line)

print("Valid IPs:", valid_ips)
print("Invalid IPs:", invalid_ips)

Output

Valid IPs: ['192.168.4.164', '69.168.4.226', '32.89.31.164', '67.168.3.227']
Invalid IPs: ['000.0000.00.00', '192.168.1.1 912.456.123.123']

Explanation:

  • for line in lines: line = line.strip(): Loop through each line and remove leading/trailing whitespace.
  • if pattern.fullmatch(line): valid_ips.append(line): If line fully matches the IP pattern, add to valid_ips.
  • else: invalid_ips.append(line): Otherwise, add to invalid_ips.
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