pfSense

Thank you for the contributions!

In general, it's best to avoid first/second person perspective. A yellowish warning box would be preferred over the red error box as well.

However, there are many instances in the GUI where the user is able to save a valid configuration that can have unintended behavior. In these cases, details are left to documentation (either online or in field descriptions). I don't believe this situation warrants a checkbox confirmation in this way.

I don't think we should change the default behavior/add extra steps to reach the current behavior.

Something that might be more palatable is a non-fatal warning handled in JavaScript. Build a list of existing IP addresses in mappings for the interface and if the users enters one that matches, display a JS box under the field that states it's already in use.

That way the user could be warned but not required to jump through hoops to override it.

I wanted to make the warning display in a "Yellow Box" too but I looked through the code and couldn't see an easy way to re-use what we have to make that happen. If it's important I will try again.

As for rewriting the whole thing as a JS/AJAX function, that's not my strongest area so Jim Pingle if you feel strongly that it needs to be done, it might take me more time or I'd leave it up to someone else. Either way thanks for the consideration.

Looks good to me.