topic Re: Need help in creating a Regex in ACS 5.8 in Network Access Control

Need help in creating a Regex in ACS 5.8

harshsinghjassal — Fri, 21 Feb 2020 18:40:01 GMT

Hello Members,

I need some help in creating a regex in ACS 5.8 to permit all ip address in the command set.

The commands I want to use in the command set are :

ip address <x.x.x.x> 255.255.255.252

ip mroute vrf mssbdata <x.x.x.x> 255.255.255.255 <x.x.x.x>

neighbor <x.x.x.x> activate

X.X.X.X can be any ip address.

Please suggest !

Re: Need help in creating a Regex in ACS 5.8

Arne Bier — Wed, 22 Nov 2017 23:16:30 GMT

Regular expression syntax doesn't provide a numerical range checking operator, so we have to build it ourselves. My suggestion below is tailored towards valid IPv4 address ranges as much as possible.

([1-9]|[1-9][0-9]|[12][0-9][0-9])\.([0-9]|[1-9][0-9]|[12][0-9][0-9])\.([0-9]|[1-9][0-9]|[12][0-9][0-9])\.([0-9]|[1-9][0-9]|[12][0-9][0-9])$

Without complicating the regex any more, it will allow examples such as

1.0.0.0 - 299.299.299.299 (but the IOS would flag an error if you entered an illegal IP address - the question is whether you want your regex to guard you from that too? Yes, maybe. Would be nice. But would possibly make the regex look even uglier.

I am open to other suggestions

Test your regex here https://regex101.com/

Re: Need help in creating a Regex in ACS 5.8

Arne Bier — Wed, 22 Nov 2017 23:46:20 GMT

I have made v2.0 that now enforces the legal IPv4 syntax

^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])$

I told you'd it's gonna get ugly 🙂

Re: Need help in creating a Regex in ACS 5.8

harshsinghjassal — Thu, 23 Nov 2017 19:12:30 GMT

Hello Arme,

Thanks for sharing the regex, I tried using the regex below:
"^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])$"

unfortunaty it's too long be added in the command set.
We don't want to restrict the user to enter any ip address till the time they are using the authorized commands in the command set.
Example below:
ip address 255.255.255.252

x.x.x.x can be any Ip address.

Please suggest.

Regards

Singh

Re: Need help in creating a Regex in ACS 5.8

Arne Bier — Thu, 23 Nov 2017 22:02:19 GMT

How about this one? It does some moderate checking to ensure that some 1-3 digit dotted decimal is entered, but no range checking is done in each decimal.

^([0-9]{1,3}\.){3}[0-9]{1,3}$

Re: Need help in creating a Regex in ACS 5.8

harshsinghjassal — Wed, 21 Mar 2018 14:31:11 GMT

Hello Arne,

Thanks for the regex, It worked like a charm.. Thanks Again...

Regards

Harshdeep Singh