Last night I set up ppp on Knoppix linux, it worked fine and I could dial up my ISP with kppp. I used apt-get to install some stuff (webmin and synaptic), set up my printer (CUPS) and all was well.

This morning, it no longer works. The "TR" light on the modem comes on as the system boots and the "RD" light flashes on at regular (~ 3 second) intervals. I assume the serial port (ttyS0) is busy, but I can't find any running services which might be causing this. Attempting to reset the modem using the kppp mini-terminal causes the "TR" light to flash off, then it immediately comes back on. I can't seem to send AT commands to the modem, presumably because of the busy state of the serial port.

This is a new one on me... does anyone have a suggestion as to why this might be happening, and a possible solution?

Bartman1234567

OK, I sussed this one out...

There was a service running called "brltty" which is a braille service for the sight impaired. I had tried to uninstall this using synaptic (an apt front-end). The uninstall failed, I thought no more of it, but it turns out that this was the process that was tying up ttyS0.

As soon as I killed the process the "TR" light on the modem went out and I could dial out again.

Problem solved...

Bartman1234567