DOS Door Recipe

Concrete recipe for getting a DOS door (e.g. LORD)
running under DOSBox-staging on Linux behind ANetBBS.

Ingredients

DOSBox-staging 0.81+ (apt install dosbox-staging on Debian/Ubuntu)
Xvfb (apt install xvfb) for headless runs
The DOS door's original files (preserve them as-is)
TCP nullmodem patch baked into DOSBox-staging (default since 0.81)

Steps

1. Drop the door into place

sudo mkdir -p /var/lib/anetbbs/doors/lord
sudo chown stingray:stingray /var/lib/anetbbs/doors/lord
sudo -u stingray cp -a /path/to/lord/* /var/lib/anetbbs/doors/lord/

2. Configure DOSBox

Make a lord.conf next to the binaries. The two essential
sections:

[serial]
serial1 = nullmodem server:9001
serial2 = disabled

[autoexec]
mount c .
c:
LORDCFG -nodes 1
LORD /N1 /B19200

Pick a free TCP port (9001 here) — used by the DosBridge.

3. Register the door

/admin/games/ → Add Game, type door_dos:

Field	Value
Name	LORD
Description	Legend of the Red Dragon
Working dir	`/var/lib/anetbbs/doors/lord`
Command	`xvfb-run -a dosbox-staging -conf lord.conf`
Bridge port	`9001`
Max nodes	1
Time limit	30 min
Idle timeout	5 min

4. First test

Play it from your sysop account first. Watch
journalctl -u anetbbs-telnet -f — you should see:

bridge connected to 127.0.0.1:9001
bridge: 215 bytes in, 4096 bytes out, ...
door exited code 0 — bridge closing

If you see "bridge: 0 bytes in, 0 bytes out", DOSBox isn't talking
back. Common causes:

serial1=stdio instead of nullmodem server: (old config)
Port already in use (ss -tnlp | grep 9001)
Door config still pointing at COM1=stdio inside the door itself

5. Ship it

If the test works, make sure the user-side path works too — log
in as a regular user and play it.