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That whole section is talking about outbound connections: When an internal endpoint opens an outgoing session through a NAT, the NAT assigns a filterin
by Dagger2 9mo ago
That whole section is talking about outbound connections:
When an internal endpoint opens an outgoing session through a NAT,
the NAT assigns a filtering rule for the mapping between an internal
IP:port (X:x) and external IP:port (Y:y) tuple.
When you connect outwards, the NAT creates a state table entry which matches inbound packets corresponding to that outbound connection, and this section is discussing which packets will match those entries.
Don't get distracted by its use of the word "filtering". It's not talking about unsolicited inbound connections, which is what we're talking about in this thread.
- deng 9mo ago> That whole section is talking about outbound connections Erm... no? Immediately after the paragraph you cited, it continues with The key behavior to describe is what criteria are used by the NAT to filter packets originating from specific external endpoints. and then, on "Address-Dependent Filtering", it says Additionally, the NAT will filter out packets from Y:y destined for the internal endpoint X:x if X:x has not sent packets to Y:any previously [...]. In other words, for receiving packets from a specific external endpoint, it is necessary for the internal endpoint to send packets first to that specific external endpoint's IP address. Meaning: unsolicited inbound connections will be filtered out.