focal (3) snmpm_network_interface_filter.3erl.gz

NAME

       snmpm_network_interface_filter - Behaviour module for the SNMP manager network-interface filter.

DESCRIPTION

       This    module    defines    the    behaviour    of    the    manager   network   interface   filter.   A
       snmpm_network_interface_filter compliant module must export the following functions:

         * accept_recv/2

         * accept_send/2

         * accept_recv_pdu/3

         * accept_send_pdu/2

       The semantics of them and their exact signatures are explained below.

       The purpose of the network interface filter is to allow for filtering  of  messages  (accept  or  reject)
       receive and send. This is done on two levels:

         * The  first level is at the UDP entry / exit point, i.e. immediately after the receipt of the message,
           before any message processing is done (accept_recv) and immediately before sending the message, after
           all message processing is done (accept_send).

         * The  second  level  is  at  the  MPD  entry  /  exit  point, i.e. immediately after the basic message
           processing (accept_recv_pdu) / immediately before the basic message processing (accept_send_pdu).

       Note that the network interface filter is something which is used by the network interface implementation
       provided by the application (snmpm_net_if and snmpm_net_if_mt). The default filter accepts all messages.

       A network interface filter can e.g. be used during testing or for load regulation.

       Legacy  network  interface  filter modules used arguments on the form (IpAddr, PortNumber,...) instead of
       (Domain, Addr, ...), and if the SNMP manager is run without changing the configuration to  use  transport
       domains the network interface filter will still get the old arguments and work as before.

DATA TYPES

       port() = integer() > 0
       pdu_type() = 'get-request' | 'get-next-request' | 'get-response' |
                    'set-request' | trap | 'get-bulk-request' | 'inform-request' |
                    report | trappdu

       See also the  data types in snmpa_conf.

EXPORTS

       accept_recv(Domain, Addr) -> boolean()

              Types:

                 Domain = transportDomain()
                 Addr = transportAddressWithPort()

              Called at the reception of a message (before any processing has been done).

              For the message to be rejected, the function must return false.

       accept_send(Domain, Addr) -> boolean()

              Types:

                 Domain = transportDomain()
                 Addr = transportAddressWithPort()

              Called before the sending of a message (after all processing has been done).

              For the message to be rejected, the function must return false.

       accept_recv_pdu(Domain, Addr, PduType) -> boolean()

              Types:

                 Domain = transportDomain()
                 Addr = transportAddressWithPort()
                 PduType = pdu_type()

              Called  after  the basic message processing (MPD) has been done, but before the pdu is handed over
              to the server for primary processing.

              For the pdu to be rejected, the function must return false.

       accept_send_pdu(Domain, Addr, PduType) -> boolean()

              Types:

                 Domain = transportDomain()
                 Addr = transportAddressWithPort()
                 PduType = pdu_type() > 0

              Called before the basic message processing (MPD) is done, when a pdu has been  received  from  the
              master-agent.

              For the message to be rejected, the function must return false.