Putting a board on the internet

Forwarding a port is the step that turns a board on your desk into a board anyone can call. It is one setting on your router, and it is the setting with the most consequences, so this page is blunt about what it does before it tells you how.

**Read this first. You are opening a door in your own network, and you are

the only person responsible for what comes through it.** Nobody here can see

your network, your router, or what else is on it. If you do not understand

what a port is, stop and read until you do. If the network belongs to your

employer, your landlord, your university or your parents, ask them first.

What you are actually doing

Your router blocks unsolicited traffic from the internet by default. That default is the single largest thing protecting the devices in your house: printers, cameras, NAS boxes, a television, anything that was built by somebody in a hurry and has not been updated since.

A port forward makes one exception to it. You are telling the router: traffic arriving on this port is expected, send it to this machine. Done correctly, exactly one program on exactly one device becomes reachable. Done carelessly, you can expose something you never meant to.

The specific risks

Telnet is plain text. This is a BBS, and the protocol has no encryption.

Every password typed by every caller crosses the open internet in the clear,

and anybody positioned between a caller and your board can read all of it.

That is a property of the protocol, not a bug in this software, and it was

true of every board in 1985 too. Tell your callers, and never reuse a

password on a telnet board.

Two things that will stop it working

Before blaming the router, check these. Between them they account for most failures, and the second one cannot be fixed by any setting at all.

Also worth knowing: these rules are IPv4 only on effectively all consumer routers. IPv6 is handled separately, usually as a firewall rule rather than a forward, because there is no address translation to undo.

Pick your router

Menu names move between firmware versions, and vendors rename things without warning. Where a vendor does not document something, these pages say so rather than guessing, because a confidently wrong menu path wastes more of your time than an honest gap.

A safer way to try it first

You do not have to open anything to run a board. On your own network it works immediately, and callers on the same wifi can dial it by address or by unleashed.local with any terminal program. If you want people outside to reach it without opening a port, a VPN into your own network, or a tunnel from a machine you rent, both work and neither puts your address on a scanner's list.

Forward the port when you have decided you want a public board, not to find out whether the software works.