Question

What words do the regex expression "d[iy]e" search for?

What does the "(?i)p[(oo|ou)]r" filter tell wireshark to search for?

Answer 1

1.). In the regular expression given in question 1., It will search for an expression starting with d with subsequent presence of either 'i' or 'y' and ending with 'b'. The square bracket in the expression represent a class of characters mentioned inside the square bracket which mark the presence of of any of the characters inside it in the target expression.

2.). In the given regular expression in the question number 2, the wireShark is being commanded to search for string starting with 'p' and subsequently having 'oo' or 'ou' and ending with 'r'. The part of filter (?i) tell the filter to ignore the the case of the the word to be filtered. It will search for or the given string of upper or lowercase letters.

It may return 'poor' or 'pOuR' or 'Poor' etc where each letter can be in uppercase or lowercase.