Filtering message retrieval
FortiOS Carrier intercepts the connection to the MMSC, and the m-retrieve.conf HTTP response from the MMSC is scanned according to the MMS content scanning settings. If the content is clean, the response is forwarded back to the client. If the content is blocked, FortiOS Carrier drops the connection to the MMSC. It then builds an m-retrieve.conf message from the associated replacement message and transmits this back to the client.
FortiOS Carrier also sends m-send.rec notifications messages to the MMSC that are then forwarded to the receiver to notify them of blocked messages.
Figure 137: MM1 MMS scanning of messages received by receiver (blocking m.retrieve.conf messages)
Filtering MM3 and MM4 messages works in an similar way to MM1 (see
Figure 138 and
Figure 139). FortiOS Carrier intercepts connections to the MMSC, and scans messages as configured. When messages are blocked, FortiOS Carrier closes sessions as required, sends confirmation messages to the sender, notifies administrators, and notifies senders and receivers of messages.
Figure 138: MM3 MMS scanning of messages sent from a sender on the Internet to an MMSC
Figure 139: MM4 MMS scanning of messages sent between operator MMSCs
Figure 140: MM7 MMS scanning of messages sent between a VASP and an MMSC
