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Are there any good docs that describe how open ports in a repl are handled by

For example, I know from experience that when I run a web server and it listens at address, it doesn't matter which port number is used because it is all translated to the HTTPS port (443) of my repl's public host name.

But there are so many more things I don't know:

  • when I start up another server, what happens to that listening port? Is it not accessible? Is it accessible, but blocks the first service? Is there a method of addressing both servers?

  • is only HTTP traffic allowed? What about other TCP services, such as IRC, SMTP, etc?

  • are UDP services allowed? How does that work?

  • are other IP services supported? For example, can a repl be pinged?

Maybe I'm not the first one to ask these questions?
I couldn't find a guide to this aspect of using's service.

Answered by Coder100 [earned 5 cycles]
View Answer

Only one port gets listened to at a time, any new ports opened gets ignored.
The other ones I don't believe work, but you could try
It is not against the tos
Yes a repl can be pinged, it's not against the tos


Thanks! That helps clear stuff up.
So it seems there's no official help doc for this?
Do you know about non-HTTP TCP or UDP? Does that work?
Whoops! I didn't read that part of your reply on the first attempt


@ceilingrat yeah sorry no
which is weird
the closest is