[General]

this code is implementation of simple VPN protcols which hides traffic from Man-In-Middle By encrypting Packets. this is done cause of requested task ref: https://github.com/mysteriumnetwork/winter-is-coming/blob/master/quests/Secret_Whispering.md this implmentation idea is very simple and this code is very dummy(because I did it when I was deploying and maitaing my production servers) and I will mention how could we promote it. to hide packets from (white walkers!) we should encrypt all network traffic which they could sniff. we could handle this by TUN/TAP that provides virtual interface to user-space program, there is another way that could helps us is using iptables ( by REDIRECT and write our app by RAW_SOCKET) or write custom Linux driver for network and at worse case scenario (by passing linux kernel network stack) we could handle traffic manually( by DPDK. the final solution depends on many situations and if we had no high traffic we could use iptables (simpler and slower ) or TUN/TAP (intermediate) but for high traffic(I mean more than 5Gbps) probebly we should bypass kernel!

[what does this code do?]

this project contains below files:

1. config.go (that should retreive configs from file and env)
2. encryption.go (that encrypts/decrypts byte array)
3. main.go (that inits TUN device and capture packets then sends them over network to target machine)

[flow:]

1. parse config (by calling ParseConfig)
2. init TUN device and configure it and make it up (user should set address and define routes manually to his device)
3. start a thread (go routine) to capture packets from TUN device and try to encrypt and to send them to target machine over network using UDP protocol.
4. start a thead (go routine) to listen to network and receive packets and try to decrypt and push them to TUN device. [why TUN device is better than TAP for this code?]

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as far as I know TUN device packets pass through linux routing, so already it could handle routing and many unnessecry challenges, but TAP is a layer 2 device and if I used it may force me to handle parse ethernet frame and routing mannually!

[Improvment]

1. Performance

   1.1 it is better to use SO_REUSEPORT option for UDP sockets(becuase it allows to multiple thread/process to listen on same port) .

   1.2 it is better to run multiple thread(go routine) to increase capture and transfer performance

   1.3 general linux kernel option may helps performance of ip layer/ or directly use BSD!!

2. code

   2.1 read configs from file and environment

   2.2 better Golang coding style

[compile]

to compile the code simply :

/usr/bin/go *go