$1 Corresponds to the first opening capturing parenthesis, $2 corresponds to the second one. You probably want to use $5 instead of $2 - let us count:

((([2]([0-4][0-9]|[5][0-5])|[0-1]?[0-9]?[0-9])[.]){3}(([2]([0-4][0-9]|
+[5][0-5])|[0-1]?[0-9]?[0-9]))).*(
123   4                                              56   7
[download]