pylcx

pylcx

A multi-user asynchronous port forwarding tool based on the CHAP protocol , which provides a web-side management and monitoring platform, implements quota management based on duration and traffic, counts user traffic usage in real time and generates detailed orders, which are displayed on the front end in the form of charts.

Protocol: Enhanced CHAP protocol

Front-end: vue.js + vuex + vue-router + vue-cli + axios + element-ui + v-chart

Backend: asyncio + sanic + sanic_cors + sanic_jwt + aiomysql

overall architecture

Single user mode (BS architecture, sanic and mysql are both in Remote Listen)

Multi-user mode (the BS architecture diagram is omitted in the figure, see the figure above for details)

Protocol design

initial agreement

Enhanced CHAP protocol (modified handshake part)

Parameter description

 (back_end) root@iZ2zehx50rbasf3o9jdehaZ:~/pylcx/back_end# python main.py -h
usage: main.py [-h] {listen,slave} ...

async LCX with CHAP

positional arguments:
  {listen,slave}  choose a mode to run
    listen        run in listen mode
    slave         run in slave mode

optional arguments:
  -h, --help      show this help message and exit

 (back_end) root@iZ2zehx50rbasf3o9jdehaZ:~/pylcx/back_end# python main.py listen -h
usage: main.py listen [-h] -p PORT [-a ADDR] [-v]

optional arguments:
  -h, --help     show this help message and exit
  -p PORT        Port listen for slave side
  -a ADDR        Address for a web server to manage users, default
                 0.0.0.0:8000
  -v, --verbose  verbose log (repeat for more verbose)

 (back_end) root@iZ2zehx50rbasf3o9jdehaZ:~/pylcx/back_end# python main.py slave -h
usage: main.py slave [-h] [-b BIND] -l LOCAL -r REMOTE -u USER [-v]

optional arguments:
  -h, --help     show this help message and exit
  -b BIND        Open a bind port at remote listen, connected by remote
                 client, default 0 (random port)
  -l LOCAL       Local server address in format host:port
  -r REMOTE      Remote listen address in format host:port
  -u USER        User in format username:password
  -v, --verbose  verbose log (repeat for more verbose)

Main modules

main.py : program entry, read command line parameters and configure logs

chap.py : The data reading and writing module at the bottom of the protocol

listen.py : core module of remote listen

slave.py : the core module of local slave

server.py : core module of sanic app

User passwords are encrypted and stored using MD5 salt, and the handshake of the protocol uses random factors to prevent replay attacks.

The front-end and back-end are separated. The back-end uses Sanic to provide RESTful API and uses JWT for cross-domain authentication.

The protocol and two-way port forwarding are implemented based on asyncio, and the database uses aiomysql, and the entire backend is asynchronous and non-blocking.