APM Browser Check

I have to do something similar for a client, but we're not tied to exact version numbers, we just reject certain browsers. Here's a very basic iRule you can use to reject off of major browser types, you can modify it to get as exact as you want. This will block anything except Safari and MSIE, and throw a custom webpage if it detects anything except these two user agents. Note that Chrome's user-agent says it's everything so it will likely get through unless you throw another condition in there.

when HTTP_REQUEST {
    Block browsers that aren't MSIE or Safari
    if { not ([string tolower [HTTP::header "User-Agent"]] contains "safari" or [string tolower [HTTP::header "User-Agent"]] contains "msie")}{
log local0. "Bad user agent:[HTTP::header "User-Agent"]"
        HTTP::respond 200 content [ifile get "usa_a_supported_browser_html"]