Redirection when clients are at /

An HTTP client cannot send a null URI. Something like this should do:

when HTTP_REQUEST {

    Check for anything not portal.site.com/
   if {"[string tolower [HTTP::host]][HTTP::uri]" eq "portal.site.com/"}{

      pool maint_pool

   } else {

      HTTP::redirect "http://portal.site.com/"
   }
}

This assumes that portal.site.com/ doesn't reference any other URIs under portal.site.com. If it did, you could add them to a switch statement:

when HTTP_REQUEST {
    Check for host of portal.site.com
   if {[string tolower [HTTP::host]] eq "portal.site.com"}{
       Check if URI is a maintenance URI
      switch -glob [HTTP::uri] {
         "/maint/*" -
         "/maintenance.jpg" -
         "/maintenance.css" -
         "/maintenance.html" {
            pool maint_pool
            return
         }
      }
   }
    If we're still in the iRule, the request wasn't for a maintenance URI, so redirect the request
   HTTP::redirect "http://portal.site.com/"
}

Aaron