We manage the server via SMS

It all started with the fact that I dug out a huaweiE1550 USB modem, which I bought last summer to organize a backup Internet channel, in a shelf with glands. He did not work long then and, as unnecessary, was removed to the “bunker” until better times. The first thing I did was unlock it for working with MTS (it so happened historically that I prefer this particular operator). Initially, it came up with the idea of ​​sending SMS with warnings from Nagios, instead of mail. After a quick run through the Internet, I came across an smsd daemon to send / receive sms-ok from the smstools package. After reading the documentation on this beast, the idea came to my mind that you can receive messages from the necessary phones, with commands for the server. So the idea was born “Manage the server via SMS”, which can be used for anything: reboot the server, turn it off,

We configure the modem

First you need to make friends with our modem and Linux (by the way, I'm using Centos 5.5). We stick the modem into one of the free usb ports. The first thing that you have to deal with is that the modem is defined as a CD-ROM, but as you know, you won’t send SMS messages and you won’t receive them. In order to fix this matter for us, you just need to feed the modem this command: AT ^ U2DIAG = 0 (0 - only modem, 1 - modem + cd-rom, 255 - modem + cd-rom + cardreader, 256 - modem + cardreader ) If you have a computer with Windows installed on hand, open HyperTerminal, connect to the modem, enter the command: AT ^ U2DIAG = 0 and skip the next step.

So, we force the modem to be a modem, and not some kind of CD-ROM under Linux. First you need to put the packagesusb_modeswitch and minicomyum --enablerepo=rpmforge install usb_modeswitch minicom , then create / edit /etc/usb-modeswitch.conf : And drag the modem to another port, wait 5-10 seconds (it is necessary for the modem to be detected as a CD-ROM) and run as root and see about the following : New ttyUSB devices should appear : We start, configure the serial port to work with / dev / ttyUSB0, exit the settings, start the terminal, then give the command AT ^ U2DIAG = 0 and get ok in response The procedure for turning the modem into a modem is finished, we are in the process of installation / configuring smstools.
DefaultVendor = 0x12d1
DefaultProduct = 0x1446
MessageEndPoint = "0x01"
MessageContent = "55534243000000000000000000000011060000000000000000000000000000"

usb_modeswitch
Looking for target devices ...
No devices in target mode or class found
Looking for default devices ...
Found default devices (1)
Accessing device 004 on bus 007 ...
Using endpoints 0x01 (out) and 0x81 (in)
Inquiring device details; driver will be detached ...
Looking for active driver ...
OK, driver found ("usb-storage")
OK, driver "usb-storage" detached

SCSI inquiry data (for identification)
-------------------------
Vendor String: HUAWEI
Model String: Mass Storage
Revision String: 2.31
-------------------------

USB description data (for identification)
-------------------------
Manufacturer: HUAWEI Technology
Product: HUAWEI Mobile
Serial No.: not provided
-------------------------
Setting up communication with interface 0 ...
Trying to send the message to endpoint 0x01 ...
OK, message successfully sent
Device is gone, skipping any further commands
-> Run lsusb to note any changes. Bye.


ls /dev | grep ttyUSB
ttyUSB0
ttyUSB1
ttyUSB2

minicom –s

Smstools

Oddly enough, in the huge rpmforge repositories there was no place for such a most useful package as smstools. But it doesn’t matter, on the Internet and on the manufacturer’s website it is enough. I found the package: smstools-3.0.10-4.el5.i386.rpm and “used” it rpm –i smstools-3.0.10-4.el5.i386.rpm. We set up smstools, the file /etc/sms.conf : the settings are pretty clear, start the daemon, and check this miracle: (does not understand the Cyrillic alphabet, I need to convert it to UCS-2BE , I won’t consider this article) and wait for SMS messages on the mobile phone . If the coveted message did not come, put loglevel = 7 in the config and go for the tambourine. Everything rose from me the first time.
devices = huaweiE1550
logfile = /var/log/smsd.log
loglevel = 2

[huaweiE1550]
device = /dev/ttyUSB0
baudrate = 115200
rtscts = no
init = at+cpms="sm","sm",""
incoming = yes
incoming = high

service smsd startsmssend 9128141111 ‘test message’

smsctrl daemon

So we can talk, we must learn to listen!
If you send an SMS to the SIM card number in the modem, after a while smsd will create a file in /var/spool/sms/incoming/huaweiE1550.* with the following contents: Accordingly, we will check these files for the presence of commands for managing the server. There are two ways to do this: 1st small daemon on bash, 2nd built-in event handler in smsd.
From: 79128141111
From_TOA: 91 international, ISDN/telephone
From_SMSC: 79126313431
Sent: 11-03-02 08:05:46
Received: 11-03-02 08:08:09
Subject: huaweiE1550
IMSI: 2500XXXXXXXXXXX
Report: no
Alphabet: ISO
UDH: false

Test message

1st method

#!/bin/sh# SMSCtrl# chkconfig: - 55 45# description: Sms control, Egor N. Zuskin, 2011, http://www.it2k.ru/projects/smsctrl
. /etc/rc.d/init.d/functions
DAEMON=smsctrl
REFRESH_TIME=15
COMMAND_CHAR="#"
INCOMING_DIR=/var/spool/sms/incoming
ALLOW_PHONES="79128141111 79128141112"
SEND_BACK_REPORT=YES
to_log(){
        text=$1export LANG=en_EN
        log_date=`date "+%b %d %H:%M:%S "`
        log_host=`hostname -s`
        echo"$log_date$log_host$DAEMON: $text" >> /var/log/$DAEMON.log
}
start() {
        echo -n "Starting $DAEMON: "$0 --daemon && success || failure
        RETVAL=$?
        echo
        [ $RETVAL = 0 ] && touch /var/lock/subsys/$DAEMON
        to_log "Starting ..."return$RETVAL
}
stop() {
        # Stop daemon.echo -n "Shutting down $DAEMON: "
        killproc $0
        RETVAL=$?
        to_log "Stopping ..."echo
        [ $RETVAL = 0 ] && rm -f /var/lock/subsys/$DAEMON
}
run() {
    for File in $(ls $INCOMING_DIR); do
        Allow=0
        for Phone in$ALLOW_PHONES; do
            cat $INCOMING_DIR/$File | grep "From: $Phone" > /dev/null 2>&1
            [ $? -eq 0 ] && Allow=1
        done;
        [ $Allow -eq 0 ] && continue
        cat $INCOMING_DIR/$File | grep "$COMMAND_CHAR"
        [ $? -ne 0 ] && continue
        FromPhone=`cat $INCOMING_DIR/$File | grep "From:" | cut -d " " -f2`
        command=`cat $INCOMING_DIR/$File | grep "$COMMAND_CHAR" | cut -d "$COMMAND_CHAR" -f2`
        to_log "Incoming command: $command from $FromPhone"
        out=`$command`
        if [ "$SEND_BACK_REPORT" = "YES" ]; then
            smssend $FromPhone"$out"
            to_log "Send sms to $FromPhone: $out"fi
        rm -f $INCOMING_DIR/$File
        to_log "Deleting file $INCOMING_DIR/$File"done
}
daemon() {
        exec >/dev/null
        exec 2>/dev/null
        (
        trap"" TERM
        while [ true ]; do
            run
            sleep $REFRESH_TIME;
        done;
        )&
}
case"$1"in
    --daemon)
          daemon
          ;;
    run)
          run
          ;;
    start)
          start
          ;;
    stop)
          stop
          ;;
    restart)
          $0 stop
          $0 start
          exit $?
          ;;
    status)
          status $DAEMONecho
          ;;
    *)
          echo"Usage: $DAEMON {start|stop|restart|status|run}"exit 1
  esacexit 0

COMMAND_CHAR="#" – Признак команды
INCOMING_DIR=/var/spool/sms/incoming – Директория для входящих смс-ок
ALLOW_PHONES="79128141111 79128141112" – Номера с которых разрешены команды
SEND_BACK_REPORT=YES – Отправлять вывод смс-ой обратно

In order not to bother with all sorts of pass phrases, etc. it was decided to accept commands only from certain numbers (I did not check how the SMS would look from the replacement numbers) and check for the presence of special characters in front of the team in order to fence off a random SMS.

Save demon /etc/init.d/smsctrl , chkconfig --add smsctrl,service smsctrl start

2nd method

Add to /etc/smsd.conf :
eventhandler = /root/bin/sms_event.sh
create /root/bin/sms_events.sh

#!/bin/bash

COMMAND_CHAR="#"
ALLOW_PHONES="79128141111 79128141112"
SEND_BACK_REPORT=YES
[ "$1" = "RECEIVED" ] || exit 0
to_log(){
    text=$1export LANG=en_EN
    log_date=`date "+%b %d %H:%M:%S "`
    log_host=`hostname -s`
    echo"$log_date$log_host$text" >> /var/log/smsctrl.log
}
File=$2
Allow=0
for Phone in$ALLOW_PHONES; do
    cat $File | grep "From: $Phone" > /dev/null 2>&1
    [ $? -eq 0 ] && Allow=1
done;
[ $Allow -eq 0 ] && exit 0
cat $INCOMING_DIR/$File | grep "$COMMAND_CHAR"
[ $? -ne 0 ] && exit 0
FromPhone=`cat $File | grep "From:" | cut -d " " -f2`
command=`cat $File | grep "$COMMAND_CHAR" | cut -d "$COMMAND_CHAR" -f2`
to_log "Incoming command: $command from $FromPhone"
out=`$command`
if [ "$SEND_BACK_REPORT" = "YES" ]; then
    smssend $FromPhone"$out"
    to_log "Send sms to $FromPhone: $out"fi
rm -f $File
to_log "Deleting file $File"

Check

Create the file /root/bin/test.sh with the following contents:

#!/bin/bash

ls –la /etc | grep $1

Then we pick up the phone and send an SMS with the text #/root/bin/test.sh smsto the coveted number and look at the log tail –f /var/log/smsctrl.log, if everything is fine, an SMS of the form will arrive in response:smsd.conf

Conclusion

I have this solution, by SMS it opens the ssh port for incoming connections. I think this is not the only application, just include a little imagination.

Useful links for setting up huawei E1550 and smsd
1: SMSTools 3 - gateway for sending SMS
2: Need an article about SMS center with a Huawei E1550 modem?
3: How to “tame” the MTS-modem Huawei E1550

Thank you for your attention, I look forward to your comments.

UPD According to the remark of my good friend, I added the implementation of processing SMS messages using smsd.