IP Address Regex Python Validator

What Is an IP Address?

An IP address is a unique identifier assigned to each device on a network. IPv4 addresses use four numbers (0–255) separated by dots, like:

192.168.0.1

To validate this format, we use a regex pattern that checks:

• Exactly four octets

• Each ranging from 0–255

• Dot separators (.)

Regex Pattern for IP Address in Python

Here’s a regex that accurately validates standard IPv4 addresses:

^((25[0-5]|2[0-4][0-9]|1?[0-9]{1,2})\.){3}(25[0-5]|2[0-4][0-9]|1?[0-9]{1,2})$

Explanation:

• 25[0-5] → matches 250–255

• 2[0-4][0-9] → matches 200–249

• 1?[0-9]{1,2} → matches 0–199

• The entire pattern ensures 4 such numbers, separated by .

Python Code Example

import re

def is_valid_ip(ip):
    pattern = re.compile(
        r'^((25[0-5]|2[0-4][0-9]|1?[0-9]{1,2})\.){3}'
        r'(25[0-5]|2[0-4][0-9]|1?[0-9]{1,2})$'
    )
    return bool(pattern.fullmatch(ip))

# Test inputs
ips = [
    "192.168.0.1",
    "255.255.255.255",
    "999.100.100.100",  # Invalid
    "172.16.254.01"
]

for ip in ips:
    print(f"{ip} -> {is_valid_ip(ip)}")

Use Cases

• Form Validation: Validate user-entered IPs in web apps

• Firewall Rules: Match and filter network IPs

• Device Configuration: Validate inputs in local or cloud-based dashboards

• Combine with: MAC Address Regex Python Validator or Date Regex Python Validator to sync IPs with timestamps

Pro Tips

• 🔄 Always trim whitespaces before validation (ip.strip())

• 🔒 Avoid trusting client-side validations—validate on the server too

• 🔀 Combine with subnet pattern checks for CIDR ranges

• 🧠 Use in scripts with the GUID Regex Python Validator to track devices over networks