snmpa_network_interface_filter(3erl)			     Erlang Module Definition			      snmpa_network_interface_filter(3erl)

NAME

       snmpa_network_interface_filter - Behaviour module for the SNMP agent network-interface filter.

DESCRIPTION

       This  module defines the behaviour of the agent network interface filter. A snmpa_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 (
       snmpa_net_if ). The default filter accepts all messages.

       A network interface filter can e.g. be used during testing or for load regulation. If  the  intended  use  is  load  regulation,  see  also
       req_limit and the function register_notification_filter .

DATA TYPES

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

EXPORTS

       accept_recv(Ip, Port) -> boolean()

	      Types  Ip = ip_address()
		     Port = port()

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

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

       accept_send(Ip, Port) -> boolean()

	      Types  Ip = ip_address()
		     Port = port()

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

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

       accept_recv_pdu(Ip, Port, PduType) -> boolean()

	      Types  Ip = ip_address()
		     Port = port()
		     PduType = pdu_type()

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

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

       accept_send_pdu(Targets, PduType) -> Reply

	      Types  Targets = targets()
		     targets() = [target()]
		     target() = {ip_address(), port()}
		     PduType = pdu_type() > 0
		     Reply = boolean() | NewTargets
		     NewTargets = targets()

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

	      For the message to be discarded all together, the function must return false .

	      Note that it is possible for this function to filter out targets (but not add its own) by returning an updated Targets list  (  New-
	      Targets ).

Ericsson AB							     snmp 4.19				      snmpa_network_interface_filter(3erl)