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Old 05-31-2005, 03:03 AM   #1
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Modem to Modem connection to test dial-up webcam server


This is a two part question. I am starting (trying) to set up a webcam server using Redhat 9. The machine will eventually be on the end of a phone line so gaining access will require dialing in to access the webcam pictures. The webcam will overlook a go-kart track so people can see the weather and how busy the track is.

I want to set up two accounts. One running SSH for remote admin, the other fo r a single guest with about the same rights as anonymous ftp. The idea is to restrict ftp to a single person who will use this access to grab an image file and update a public website. I don't want to allow general public access directly to the webcam server.

At present, I am trying to set up and test mgetty. I am trying to directly connect an internal modem in my Win98 PC (client) to the external Hayes modem on my webcam server. I have added a circuit to supply the correct DC voltage to the phone line. I can get Minicom and Hyperterminal "talking" to each other. What I can't do is get the hayes modem and mgetty to respond to a "call" from Hyperterminal. The mgetty logs show it times-out on carrier not detected. The first question is : Can anyone suggest how I can get two modems to work together with mgetty and without a PABX (I only have one phone line to my house)?

The second question relates to setting up mgetty. I have found "How To's" on dial up servers. They don't explain how to set-up what I want. I don't want the guest to be able to do anything except FTP an image from the webcam server. The admin login needs full access and rights because the server will be physically located along way from my home. Can anyone suggest how to correctly configure mgetty to link to ftp and to an admin user account?

Any help would be much appreciated.
Old 05-31-2005, 05:07 AM   #2
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I forgot to add that I can hear the win98 client modem dial the number but there is no handshaking between the modems. Wait for dial tone has been disabled on the client. It seems that the server modem can't detect that it is receiving a call.

Old 06-01-2005, 04:43 AM   #3
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I have the answer to part of my question. mgetty won't respond to a 'call' from another modem because the modem can't generate a ring tone. The voltage on the phone line when before receiving a call is -48VDC. When a call comes in the ring tone is +48VDC plus 60VAC. The ring tone is neccessary to get the modem to answer the call and inform mgetty that a carrier has been detected.

The solution is to:
use a small office PABX or;
make up a phone simulator or;
have a patient friend make lots of test calls or;
get a second phone line.


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