Regex to validate port number

Question

I'm using this regex (6553[0-5]|655[0-2]\d|65[0-4]\d{2}|6[0-4]\d{3}|[1-5]\d{4}|[1-9]\d{0,3} to validate port numbers. Somehow this is not working. What is wrong with this? Can anybody point me out.

Answer 1

What exactly do you mean by not working?

You could try something like so: ^([0-9]{1,4}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])$ (obtained from here).

This will make sure that any given string is numeric and between the range of 0 and 65535.

Assuming your regular expression matches the same range, it is missing the start and end anchors (^ and $ respectively), so it would allow other strings besides the actual port.

Answer 2

When, we search "how to validate port number" on Google we unfortunately land here

However (except if you have really no other choice...),

Regex is clearly not the way to validate a port number !

"One" (slightly better) way may be:

step 1: Convert your string into number, and return FALSE if it fails
step 2: return TRUE if your number is in [1-65535] range, and FALSE otherwise

Various reasons, why Regex is not the right way ?

• Code readability (would takes few minutes to understand)
• Code robustness (there are various ways to introduce a typo, a unitary test would be required)
• Code flexibility (what if port number can be extended to a 64-bits number !?)
• etc. ...

Answer 3

Number() is the function you want "123a" returns NAN

parseInt() truncates trailing letters "123a" returns 123

<input type="text" id="txtFld" onblur="if(Number(this.value)>0 && Number(this.value)<65536){alert('valid port number');}" />

• jsfiddle

Answer 4

Here is the example I'm using to validate port settings for a firewall. The original answer will match 2 strings. I can only have 1 string match.

(6553[0-5]|655[0-2][0-9]|65[0-4][0-9][0-9]|6[0-4][0-9][0-9][0-9][0-9]|[1-5](\d){4}|[1-9](\d){0,3})

To get: 22,24:100,333,678,100:65535 my full validation (That will only return 1 match) is

(6553[0-5]|655[0-2][0-9]|65[0-4][0-9][0-9]|6[0-4][0-9][0-9][0-9][0-9]|[1-5](\d){4}|[0-9](\d){0,3})(:(6553[0-5]|655[0-2][0-9]|65[0-4][0-9][0-9]|6[0-4][0-9][0-9][0-9][0-9]|[1-5](\d){4}|[0-9](\d){0,3}))?(,(6553[0-5]|655[0-2][0-9]|65[0-4][0-9][0-9]|6[0-4][0-9][0-9][0-9][0-9]|[1-5](\d){4}|[0-9](\d){0,3}){1}(:(6553[0-5]|655[0-2][0-9]|65[0-4][0-9][0-9]|6[0-4][0-9][0-9][0-9][0-9]|[1-5](\d){4}|[0-9](\d){0,3}))?)*

Answer 5

A more strict approach is to have a regex matching all numbers up to 5 digits with the following string:

*(^[1-9]{1}$|^[0-9]{2,4}$|^[0-9]{3,4}$|^[1-5]{1}[0-9]{1}[0-9]{1}[0-9]{1}[0-9]{1}$|^[1-6]{1}[0-4]{1}[0-9]{1}[0-9]{1}[0-9]{1}$|^[1-6]{1}[0-5]{1}[0-4]{1}[0-9]{1}[0-9]{1}$|^[1-6]{1}[0-5]{1}[0-5]{1}[0-3]{1}[0-5]{1}$)*

Answer 6

The accpeted answer by npinti is not right. It will not allow to enter port number 1000, for example. For me, this one (not nice, I'm a beginner) works correctly:

/^((((([1-9])|([1-9][0-9])|([1-9][0-9][0-9])|([1-9][0-9][0-9][0-9])|([1-6][0-5][0-5][0-3][0-5])))))$/

Answer 7

"^((6553[0-5])|(655[0-2][0-9])|(65[0-4][0-9]{2})|(6[0-4][0-9]{3})|([1-5][0-9]{4})|([0-5]{0,5})|([0-9]{1,4}))$"

It will allow everything between 0-65535 inclusive.

Answer 8

Here is single port regex validation that excludes ports that start with 0

^([1-9][0-9]{0,3}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])

Here is validation for port range (ex. 1111-1111)

^([1-9][0-9]{0,3}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])(-([1-9][0-9]{0,3}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5]))?$

link:

https://github.com/findhit/proxywrap/issues/13

Answer 9

@npinti 's answer allows leading zeros in the port number and also port 0 means pick any available port so I would exclude that so the regex becomes

^([1-9][0-9]{0,4}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])$

If you want to allow port 0 then

^(0|[1-9][0-9]{0,4}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])$

Answer 10

The solution:

Dim Minlenght As Integer = 1
Dim Maxlenght As Integer = 65536

Regex.IsMatch(sInput,"(^\d{0},{1}$)", "{" + Minlenght, Maxlenght + "}")

Answer 11

Landed here as well, searching specifically for REGEX to validate port number. I see the approved solution was not fixed yet to cover all scenarios ( eg: 007 port, and others ) and solutions from other sites not updated either (eg).

Reached same minimal solution as saber tabatabaee yazdi, that should cover the 1-65535 range properly:

^([1-9][0-9]{0,3}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])$

Enjoy !

Answer 12

^((6553[0-5])|(655[0-2][0-9])|(65[0-4][0-9]{2})|(6[0-4][0-9]{3})|([1-5][0-9]{4})|([0-5]{0,5})|([0][0-9]{1,4})|([0-9]{1,4}))$

I have tested above regrex with Junit run the for loop from 0-65535

Ex: 00001 - 65535 with leading Zeros 1 - 65535 without leading Zeros Ex:====

1. (6553[0-5]) : 65530-65535
2. (655[0-2][0-9]) : 65500-65529
3. (65[0-4][0-9]{2}): 65000-65499
4. (6[0-4][0-9]{3}) : 60000-64999
5. ([1-5][0-9]{4}) : 10000-59999
6. ([0-5]{0,5}) : 00000-55555 (for leading Zeros)
7. ([0][0-9]{1,4}) : 00000-09999 (for leading Zeros)
8. ([0-9]{1,4}) : 0000-9999 (for leading Zeros)

Answer 13

If variable is an integer between 1 and 65536 (inclusive) then...

if [[ "$port" =~ ^[0-9]+$ && $port -ge 1 && $port -le 65536 ]]; then