irulse for url limit

You can replace condition

[string tolower [HTTP::query]] contains "redirect=/admin"

with (this will search

redirect

[string to lower [URI::query [HTTP::uri] redirect]] starts_with "/admin"

or

[string to lower [URI::query [HTTP::uri] redirect]] equals "/admin"

One other recommendation is to filter on HTTP::path instead of HTTP::uri if login string is in path part of the URI.

The final iRule can be:

when RULE_INIT {
    set static::admin_datagroup "admin_datagroup"
}
when HTTP_REQUEST {
    if {([HTTP::path] ends_with "/login/") && ([string to lower [URI::query [HTTP::uri] redirect]] starts_with "/admin")&& ! [class match [IP::client_addr] equals $static::admin_datagroup]} {
            HTTP::respond 404
    }
}