Dial-in server as a network recovery tool

It is no secret that any iron, no matter how good it is, tends to fall.
And well, if you fell unimportant server. And if the root router?
Go to the other end of the city in the middle of the night? Or to another city? Somehow I do not want.
When I faced this issue, I remembered about the modem. And that's what happened.


My configuration:
OS: Slackware 12
2 MCS9895 boards with 4 serial ports each
D-Link DFM-562E EXT VI (RTL) V.92 Modem (rs232-connected)

1. Download and install the driver for mcs9895.
In my case, I had to tweak the code with my hands, that is, replace SA_SHIRQ with IRQF_SHARED.
/ dev / ttyD * - ports of MCS9895 (8 pieces).
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2. Connect all root hardware through rs232 to the ports of mcs boards

3. Configure minicom'a configs. I did configs /etc/minirc.d0-d7
pr port /dev/ttyD0
pu baudrate 9600
pu bits 8
pu parity N
pu stopbits 1

4. We write a sh-script on a sample
#!/bin/sh
echo "welcome to rs232 console server"
echo "choose server"
echo "1 - core-gw"
echo "2 - core-sw"
echo -n "> "
read I
case "$I" in
1)
minicom -o d0
;;
2)
minicom -o d1
;;
*)
echo "good bye"
;;
esac

Next, create a user with the option -s / path / to / script
Do not forget to include it in the uucp group (or the one that owns the / dev / ttyD * devices)

5. Download and install mgetty.
In mgetty.config we write 3 lines:
port ttyS0
debug 3
data-only y

where ttyS0 is the port on which the modem hangs.

6. Rule inittab
S0: 2345: respawn: / usr / local / sbin / mgetty -x 3 / dev / ttyS0
And do kill -HUP 1

7. Voila!
You can check. And no longer keep the stash at night taxi in case of problems with the equipment.

Thank you for your attention and good luck at work.