====== Telnet ======

Telnet is the main way callers reach a ProBoard board. Every Telnet caller, and every caller of the in-browser web terminal, connects to one shared port on the PBDispatch computer. PBDispatch accepts the connection and starts a ''ProBoard.exe'' node for it.

===== Settings =====

Open **Network > Telnet Server** in PBConfig. The settings are saved in ''Configs\PBTELNET.CFG''.

{{ :v4:images:config-telnet.png?900 |The Telnet Server screen in PBConfig}}
//Figure 1. Network > Telnet Server in PBConfig.//

The **Default (23)** button next to the port box puts the standard port back. With no ''PBTELNET.CFG'' yet, the board listens on port 23 on every address, and the screen creates the file the first time you save.

^ Setting ^ Meaning ^
| Telnet server enabled | Switches the listener on or off. |
| Port | 1 to 65535. The default, 23, is what Telnet clients try first, so callers need nothing extra. With another number (2300 is common) callers must type it, for example ''telnet yourbbs.example.com 2300'', or put it in the BBS listing or the terminal's address book. |
| Listen address | Empty (or ''any'') listens on every network card. Enter one card's IPv4 address, such as ''192.168.1.10'', to listen only there. The web terminal connects to that same address. |

After changing either setting, **restart PBDispatch**. PBConfig offers to do this when you save.

If you prefer to edit the file by hand, copy ''Configs\PBTELNET.CFG.SAMPLE'' to ''Configs\PBTELNET.CFG''. It has one setting per line:

<code>
port 23
bind any
</code>

If the file has a mistake, the PBDispatch log says so and the defaults (port 23, every address) are used. A typo never takes the board offline.

===== After changing the port =====

  * Allow inbound TCP on the new port in Windows Firewall. The old rule for the old port does not help.
  * Forward the new port in your router if callers come in from the Internet.
  * Only one program can listen on a port. If PBDispatch logs //Unable to bind Telnet port N//, something else already has it: Windows' own Telnet Server, another BBS or a previous copy of PBDispatch.
  * RLogin, SSH, FTP, NNTP and the web server each have their own port on their own PBConfig screen. This setting changes none of them.

===== Stopping and starting Telnet =====

In PBDispatch, **View > Service Management** has Stop, Start and Restart buttons for Telnet. Stopping closes the port but does not disconnect callers who are already on. **Start** reads ''PBTELNET.CFG'' again, so a new port takes effect without restarting PBDispatch, provided no Telnet caller is connected at that moment.

See also [[v4:connect:login_guard|Login Guard]], which slows down and bans addresses that keep failing to log in.