• allow to run several copies of program on the same port to use all available CPU cores
• support for cryptography module and use it by default in the docker container
• drop client if it doesn't send a handshake in 10 seconds
• if the handshake was wrong, don't close a connection immediately to prevent active protocol fingerprinting
• use uvloop, high-speed implementation of event loop, if available
• fix binding on port that less than 1024 in docker container