When using regular expressions in the LoadMaster WUI, you must use an even number of quotes (single or double). The quotes must also nest correctly, for example, if you use single quotes within double quotes, the single quotes must be matched inside the double-quotes. To use a single " (double-quote) character in a regex, use %22 instead (or %27 for a single quote).

If you want to use an uneven number of quotes in a regular expression, use the API instead of the WUI.

For example, trying to set the following Match String in the WUI results in an error that says Please specify a pattern to be matched:

/\<img([^\>\/]*)\ssrc\=\"([^\"]*)\"([^\>\/]*)\/?>/

However, it is possible to set this using the API, for example:

/access/addrule?name=Example&pattern=/\<img([^\>\/]*)\ssrc\=\"([^\"]*)\"([^\>\/]*)\/?>/