regex101: simple IPv6 check

^start of line

Group 1([0-9A-Fa-f]{0,4}:){2,7}

{2,7}repeats the group contents below between 2 and 7 times:

Character Class[0-9A-Fa-f]{0,4}

{0,4}matches between 0 and 4 characters from the set below:

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

A-Fone character from A (65₁₀) to F (70₁₀) (case sensitive)

a-fone character from a (97₁₀) to f (102₁₀) (case sensitive)

:the literal : (58₁₀ / 72₈ / 3A₁₆)

Group 2([0-9A-Fa-f]{1,4}$|((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.|$)){4})

1st Alternative[0-9A-Fa-f]{1,4}$

Character Class[0-9A-Fa-f]{1,4}

{1,4}matches between 1 and 4 characters from the set below:

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

A-Fone character from A (65₁₀) to F (70₁₀) (case sensitive)

a-fone character from a (97₁₀) to f (102₁₀) (case sensitive)

$end of line

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

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

{4}repeats the group contents below exactly 4 times:

Group 4(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)

1st Alternative25[0-5]

25the literal text 25

Character Class[0-5]

0-5one character from 0 (48₁₀) to 5 (53₁₀)

2nd Alternative2[0-4][0-9]

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]

0-4one character from 0 (48₁₀) to 4 (52₁₀)

Character Class[0-9]

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

3rd Alternative[01]?[0-9][0-9]?

Character Class[01]?

?matches at most one character from the set below:

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[0-9]

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

Character Class[0-9]?

?matches at most one character from the set below:

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

Group 5(\.|$)

1st Alternative\.

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

2nd Alternative$

$end of line

Global pattern flags

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

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

^([0-9A-Fa-f]{0,4}:){2,7}([0-9A-Fa-f]{1,4}$|((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.|$)){4})$

Test String
New

Valid:
1:2:3:4:5:6:7:8
1::
::1
2001:db8:3:4::192.0.2.33
64:ff9b::192.0.2.33
FEDC:BA98:7654:3210:FEDC:BA98:7654:3210
1080:0:0:0:8:800:200C:417A
0:0:0:0:0:0:0:1
::0:0:0:FFFF:129.144.52.38
FEDC:BA98::3210:FEDC:BA98:7654:3210
::13.1.68.3

Invalid:
128.0.0.1
FEDC:BA98:7654:3210:FEDC:BA98:7654:3210:AA31

Regular Expressions 101

Regular Expression

Test String
New

Substitution
Processing...

Regular Expression

Test StringNew

SubstitutionProcessing...

Test String
New

Substitution
Processing...