Usage: dhcrelay [-4] [-d] [-q] [-a] [-D]
                     [-A <length>] [-c <hops>] [-p <port>]
                     [-pf <pid-file>] [--no-pid]
                     [-m append|replace|forward|discard]
                     [-i interface0 [ ... -i interfaceN]
                     [-iu interface0 [ ... -iu interfaceN]
                     [-id interface0 [ ... -id interfaceN]
                     [-U interface] [-g <ip-address>]
                     server0 [ ... serverN]

       dhcrelay -6   [-d] [-q] [-I] [-c <hops>] [-p <port>]
                     [-pf <pid-file>] [--no-pid]
                     [-s <subscriber-id>]
                     -l lower0 [ ... -l lowerN]
                     -u upper0 [ ... -u upperN]
           lower (client link): [address%]interface[#index]
           upper (server link): [address%]interface

       dhcrelay {--version|--help|-h}