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docs/updates/Symmetric-NAT-Transversal.md

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+Notes:
+
+Friend requests need to be routed.
+
+The current DHT should be capable of punching all NATs except symmetric ones.
+
+######
+
+Symmetric NAT hole punching:
+
+If we are not connected to the friend and if the DHT is queried and ips 
+returned for the friend are the same but the port is different, the friend is 
+assumed to be behind a symmetric NAT.
+
+Before attempting the procedure we first send a routed ping request to the 
+friend. This request is to be routed through the nodes who returned the ip of 
+the peer.
+
+As soon as we receive one routed ping request from the other peer, we respond 
+with a ping response. 
+
+Ping request/response packet:
+See: Crypto request packets in [[Crypto]]
+
+Message:
+For the ping request:
+[char with a value of 254][char with 0][8 byte random number]
+
+For the ping response:
+[char with a value of 254][char with 1][8 byte random number (The same that was sent in the request)]
+
+As soon as we get a proper ping response from the other we run the different 
+ports returned by the DHT through our port guessing algorithm.
+
+######
+
+Port guessing algorithm:
+
+Right now it just tries all the ports directly beside the known ports.(A better one is needed)
+
+######
+
+We send DHT ping requests to all the guessed ports, only a couple at a time.