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Why does http3 use UDP?
HTTP and connections Among the two most common transport protocols on the Internet, TCP is reliable and UDP isn’t. HTTP therefore relies on the TCP standard, which is connection-based. For example, Google is experimenting with QUIC which builds on UDP to provide a more reliable and efficient transport protocol.
How does P2P work behind NAT?
Consider this: if both P2P nodes behind the NAT send packets to each other’s public IP/port, the first packet from each party is discarded because it was unsolicited. And voilà the hole is punched, and UDP traffic can pass through directly between the P2P nodes.
How does nat work with incoming UDP packets from unknown?
My understanding of NAT is that UDP packets going out from the client to a specific endpoint will result in a temporary entry into the NAT table mapping the source port to the destination endpoint. (Is this right?)
How are packets related to each other in NAT traversal?
However, nothing says the packets must be related to each other beyond the IPs and ports lining up correctly. As long as some packet flowed outwards with the right source and destination, any packet that looks like a response will be allowed back in, even if the other side never received your packet!
Do you need TCP or UDP for NAT traversal?
You need two things. First, the protocol should be based on UDP. You can do NAT traversal with TCP, but it adds another layer of complexity to an already quite complex problem, and may even require kernel customizations depending on how deep you want to go. We’re going to focus on UDP for the rest of this article.
What happens when a NAT gateway goes out?
When a connection times out, a NAT gateway returns an RST packet to any resources behind the NAT gateway that attempt to continue the connection (it does not send a FIN packet). When a connection times out, a NAT instance sends a FIN packet to resources behind the NAT instance to close the connection.