IPv4 Address Regex Pattern

Validate IPv4 addresses (0.0.0.0 to 255.255.255.255) with regex. Includes boundary checking and ready-to-use patterns.

The Pattern

/\b(?:(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\b/g

How It Works

Token	Meaning
`\b`	Word boundary to prevent partial matches
`25[0-5]`	Matches 250-255
`2[0-4]\d`	Matches 200-249
`[01]?\d\d?`	Matches 0-199
`\.)`	Literal dot between octets
`{3}`	Repeat first three octets with dots
`(?:25[0-5]\|2[0-4]\d\|[01]?\d\d?)`	Final octet (same range, no trailing dot)

Test Cases

✅192.168.1.1Match

✅10.0.0.255Match

✅255.255.255.0Match

✅0.0.0.0Match

❌999.999.999.999No match

❌256.1.1.1No match

Code Examples

javascript

const ipRegex = /\b(?:(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\b/g;
const text = "Server IPs: 192.168.1.1, 10.0.0.255, invalid 999.999.999.999";
const matches = text.match(ipRegex);
console.log(matches); // ["192.168.1.1", "10.0.0.255"]

python

import re
ip_regex = r'\b(?:(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\b'
text = "Server IPs: 192.168.1.1, 10.0.0.255, invalid 999.999.999.999"
matches = re.findall(ip_regex, text)
print(matches)  # ['192.168.1.1', '10.0.0.255']

Common Use Cases

Network configuration - validate IP address inputs
Log parsing - extract IPs from server logs
Security - detect IP addresses in text for whitelisting/blacklisting
DevOps - parse infrastructure configuration files

Related Patterns

URL / HTTP Phone Number UUID

Want to test this pattern with your own data?

Try this pattern in Regex Tester →