Inter-BBS messages

Callers on other boards can see who is online on your board and send your callers a short instant message, and your callers can do the same to them. It works the way Synchronet's sbbsimsg does, and a ProBoard board and a Synchronet board can message each other.

Two small standard protocols are involved:

• UDP port 11 answers “who is online” (RFC 866). A board sends a short question; yours replies with the list of callers online now.
• TCP port 18 carries one message per connection (RFC 1312).

This is separate from MRC and from IRC.

• Receiving: who-is-online, messages, an inbox, a “messages waiting” notice at logon, live delivery while a caller is online, a screen to read and delete messages with a Reply key, and a do-not-disturb switch.
• Sending: the IMSG plug-in shows who is online on the boards in your list and lets a caller write up to 5 lines.
• Finger (off by default): other boards can finger your callers (TCP 79), and your callers can finger people on the boards in your list.
• A ready-made CHAT menu, and typed commands such as /chat and /telegram (see "/" commands).

The daily download of the list of boards is not built yet. Copy sbbsimsg.lst into Configs yourself.

1. Open Network > Inter-BBS Messages in PBConfig, set the BBS name, tick Enable and click Save (it writes Configs\PBIMSG.CFG; you can also copy PBIMSG.CFG.SAMPLE).
2. Restart PBDispatch. The log says IMSG: inter-BBS messaging on UDP 11 … and TCP 18. A cannot bind message means another program is using a port.
3. Allow the two ports in Windows Firewall:

netsh advfirewall firewall add rule name="ProBoard IMsg UDP 11" dir=in action=allow protocol=UDP localport=11
netsh advfirewall firewall add rule name="ProBoard IMsg TCP 18" dir=in action=allow protocol=TCP localport=18

1. Forward UDP 11 and TCP 18 on your router to the PC that runs PBDispatch.
2. Add menu items: function 80 (read inter-BBS messages) and 81 (do-not-disturb). To let callers send, add function 60 with the data IMSG and put IMSG.P3X in your PEX folder. Or use the ready-made CHAT menu.
3. To be listed by other Synchronet boards, add yours to the Synchronet BBS List. Its daily scan lists a system about 24 hours after it is in the list and answers on UDP 11 and TCP 18 from the Internet. Until then people can still message you if they type your address.

Messages are shown as Synchronet shows them: Instant Message from Name [BBS name]: and the text indented. At logon, messages that arrived while the caller was away are shown (up to 5, oldest first). While online, a new message pops up within about a second at the board's own prompts. The read screen (function 80) shows one message at a time: Next, Reply, Delete, Keep unread, Quit.

A message names its sender as the sender typed it, and nothing proves who sent it. The screen shows both the sender's BBS name and the address it really came from.

Not listed, and cannot be messaged: deleted users, guests, hidden users and users with do-not-disturb on. A message to one of those gets the same answer as a name that does not exist, so the port cannot be used to find out who has an account. The sysop is left out of the who-is-online list (unless hidesysop no) but can still be messaged by name.

A caller opens the menu item. The prompt is InterBBS: Anyone: Telegram, Active-Users: Message/List, or Quit. The plug-in asks every board in your list “who is online?” on entry and every 60 seconds, and announces people who arrive or leave.

A message is up to 5 lines of up to 76 characters; a blank line sends. It goes out under the caller's alias (or real name) and your bbsname.

The list of systems. Configs\pbimsg.lst is your own list and has priority: one system per line, with host name, IP address and BBS name. A second file, sbbsimsg.lst, is also used. Either may be missing.