regex101: IPv4 addresses that don't match RFC1918

Pro

Group 1(\d+)

\d+a digit, repeated at least once

Negative Lookbehind(?<!10)

10the literal text 10

Negative Lookbehind(?<!127)

127the literal text 127

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 2(\d+)

\d+a digit, repeated at least once

Negative Lookbehind(?<!192\.168)

192the literal text 192

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

168the literal text 168

Negative Lookbehind(?<!172\.(1[6-9]|2[0-9]|3[0-1]))

172the literal text 172

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 3(1[6-9]|2[0-9]|3[0-1])

1st Alternative1[6-9]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[6-9]

6-9one character from 6 (54₁₀) to 9 (57₁₀)

2nd Alternative2[0-9]

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-9]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

3rd Alternative3[0-1]

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

Character Class[0-1]

0-1one character from 0 (48₁₀) to 1 (49₁₀)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 4(\d+)

\d+a digit, repeated at least once

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 5(\d+)

\d+a digit, repeated at least once

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

25 tokens

Regular Expression

(\d+)(?<!10)(?<!127)\.(\d+)(?<!192\.168)(?<!172\.(1[6-9]|2[0-9]|3[0-1]))\.(\d+)\.(\d+)

New



No match
172.16.1.1
172.16.0.0
172.16.0.0
172.31.0.1
172.20.22.22
10.255.255.255
192.168.1.1
192.168.12.34
192.168.111.222
127.255.255.255
127.0.4.4
127.0.0.1
127.255.255.255
127.123.123.123
127.1.1.1
127.12.23.56

Match
172.15.2.2
172.33.33.33
192.167.1.1
192.169.1.1
207.168.207.11
207.168.207.22
192.2.199.199

Substitution



No match
172.16.1.1
172.16.0.0
172.16.0.0
172.31.0.1
172.20.22.22
10.255.255.255
192.168.1.1
192.168.12.34
192.168.111.222
127.255.255.255
127.0.4.4
127.0.0.1
127.255.255.255
127.123.123.123
127.1.1.1
127.12.23.56

Match
172.15.2.2
172.33.33.33
192.167.1.1
192.169.1.1
207.168.207.11
207.168.207.22
192.2.199.199