IPv4 Address (as PII identifier) Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching ipv4 address (as pii identifier), ported and verified for Python. Identity and credential patterns need both correctness and safety, since they're frequent targets for adversarial input. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# IPv4 Address (as PII identifier)
# ReDoS-safe | RegexVault — Identity & PII > Digital Identity

import re

ipv4_address_as_pii_identifier_pattern = re.compile(r'^(?:(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.){3}(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])$')

def validate_ipv4_address_as_pii_identifier(value: str) -> bool:
    return bool(ipv4_address_as_pii_identifier_pattern.fullmatch(value))

# Example
print(validate_ipv4_address_as_pii_identifier("192.168.1.1"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Identity & PII > Digital Identity category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Under GDPR (C-582/14, Breyer v Germany), IP addresses can constitute personal data when the controller has the legal means to identify the individual. Dynamic IPs assigned by ISPs are personal data. Log files containing IP addresses must comply with GDPR retention requirements.