Would like the ability to constrain the characters/pattern for bruteforcing

[kaisalmon]

I am trying to do a quick-n-dirty pentest on a system where an attacker might know that a given code is known to be (in my case) numerical.
Is it possible to constrain the characters which are attempted during the brute force to be constrained to some subset (or, even, allow only trying INPUTs that match a certain regex?)

[ffleming]

That's a great idea; I'll add it when I'm able. I make no promises on how soon that'll be, but in the meantime I'm happy to accept PRs that implement the feature