How to: Default ports
In order to eliminate the need to pass custom params/environment, the default `--listen` is dynamic and trying to be reasonable and helpful for the typical cases:

- If anything set by users to `--listen` all the logic below ignored and host:port passed in and used directly.
- If nothing set by users to `--listen` and reproxy runs outside the docker container, the default is `127.0.0.1:80` for http mode (`ssl.type=none`) and `127.0.0.1:443` for ssl mode (`ssl.type=auto` or `ssl.type=static`).
-  If nothing set by users to `--listen` and reproxy runs inside the docker, the default is `0.0.0.0:8080` for http mode, and `0.0.0.0:8443` for ssl mode.

Another default set in the similar dynamic way is `--ssl.http-port`. For run inside of the docker container it set to `8080` and without to `80`.