Checking data reception

waddles · 11-02-2013, 08:51 PM

Frequently of late I noticed the "receive data" light goes out but Firefox continues to spin. If I change to a different dialup number it helps. I have learned my ISP has been under attack so this is an impact. I would like to probe the modem without effecting the download that is in process to find if there is received data and after 3+/- seconds beep a warning if no action. Is there a place on the serial line I can test for activity? Or some other approach?

ukiuki · 11-04-2013, 07:41 AM

You could use some network traffic monitor, conky is a system monitor and have many features including network, there are several programs available to monitor the network activity.
here some:
slurm
iptraf
ethstatus
nload
bmon (bandwidth monitor)
netspeed

Regards

waddles · 11-04-2013, 11:16 AM

Thanks. I was aware there is software/hardware to do what I want but I am looking for a way to sense it from a simple shell script preferably using bourne or bash. If I knew where to look for the incoming data on the received data line programatically, then I could probably build a script around that.

waddles · 11-04-2013, 12:08 PM

This may help. I found a site which described modem access. In that I found:
fcntl(fd, F_SETFL, FNDELAY);
which while reading the port would allow checking the serial input buffer for bytes stored or 0 for none. I think this is what I need but am not sure of salient situations where this might cause data damage/loss. Can someone advise?
I vaguely remember about raw mode but if I am checking the modem from a second window while attempting to download on another am not sure if this will royally screw stuff up.