Simple SOCKS5 server using go-socks5 with auth
docker run -d --name socks5-proxy -p 1080:1080 -e PROXY_AUTH='{"<PROXY_USER_1>": "<PROXY_PASSWORD_1>", "<PROXY_USER_2>": "<PROXY_PASSWORD_2>"} esten/go-socks5-proxy
where PROXY_AUTH is a JSON map of authorized user names and the respective passwords.
curl --socks5 <docker machine ip>:1080 -U <PROXY_USER>:<PROXY_PASSWORD> https://api.ipify.org
Result must show docker host IP address.