Telnet to Serial - Any way to do it so that you don't require logon to the router?

Afternoon

I’m trying to replace some old Sixnet/Redlion routers which have “telnet to serial” functionality. The app connects to the router over telnet, and is immediately prompted for credentials from the device that is connected to the serial port.

Following instructions here: https://wiki.mikrotik.com/wiki/Serial_Port_Usage I can get most of the way.

I can telnet to the Mikrotik, but I still have to logon as user “serial” before I get prompted for logon by the device hooked to the serial port.

The software is not smart enough for me to specify two sets of credentials.

Is there a way to configure the MIkrotik (in this case LtAP mini) such that you can telnet to it (ideally on port 1000) and it just passes through to the serial device?

If not, I suppose my next plan of attack would be a generic tcp to serial device and just a normal port forward on the Mikrotik. I’m trying to avoid more parts if possible.

I’m aware this isn’t ideal for security, I would be restricting access to the telnet port from certain source IPs.

Using virtual serial port is not an option as there is more than one client that would be accessing these.

Thanks in advance!

/port remote-access add port=usb1 tcp-port=12345 protocol=raw
should do the trick - plus firewall rules in chain input of /ip firewall filter allowing access to TCP port 12345 from the permitted addresses/interfaces of course.