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@@ -7,4 +7,43 @@ This contains a short implementation of the DNS protocol, inspired by the docume
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https://github.com/EmilHernvall/dnsguide/blob/master/chapter5.md
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+## Tunnel
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+The basic tunnel is looking like that:
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+The tunnel is communicating only via TXT records, sending data happens in the following steps:
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+### Client -> Server
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+1) Client sends a DNS Question for the TXT record to `INIT.domain.com` to check if the server answers
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+2) For a correct answer, the TXT Record must be set to `ACK`
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+3) Sending a payload consists of the following messages:
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+ - DNS Request with `START.domain.com`
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+ - DNS Reply with `ACK`
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+ - DNS Request with `somedatahere.domain.com`
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+ - DNS Request with `somedatahere.domain.com`
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+ - ...
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+ - DNS Request with `END.domain.com`
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+ - DNS Reply with `ACK`
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+### Server -> Client
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+1) The client sends regular `POLL` requests
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+2) The server will provide the data to send in the `TXT Record`
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+3) Approach is the same:
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+ - DNS Request with `POLL.domain.com`
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+ - DNS Reply with `START`
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+ - DNS Request with `POLL.domain.com`
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+ - DNS Reply with `herecomesthedata`
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+ - DNS Request with `POLL.domain.com`
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+ - DNS Reply with `herecomesmoredata`
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+ - DNS Request with `POLL.domain.com`
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+ - DNS Reply with `END`
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+For the complete communication, the data is first "encrypted" via `xor()` and then base64 encoded to hide
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+the payload at least a little bit
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