It's a real shame we can't use the IP range calculator unless we perform a check beforehand, so I'd love to have it changed.
Talk:Requests for comment/CheckUser requirements
@Ле Лой There's NativeForeigner's calculator which you can use.[http://www.nativeforeigner.com/calc/]
And on en.wiki, https://en.wikipedia.org/wiki/Template:IP_range_calculator ~~~~
Thanks, I know, but after you get used to this one you open it semi-autmoatically even for non-CU-related things :D
@Ле Лой The IP range calculator can be used just accessing Special:CheckUser. If it does not show, some JS might be hidding it.
The ideas about improving the CU extension's handling of User Agents are pretty good. It may be worth noting that the linked UserAgentString.com does offer an API (http://useragentstring.com/pages/api.php), and although an in-house solution could be used this would reduce dev time a little.
As for forged UAs, I doubt it's going to be possible to do anything other than state that the provided UA is non-standard