Friday, May 28, 2010

Nagios + SMS notifications with Gammu and Siemens MC35i

What you need :

- a working Nagios
- a GSM modem (this has been tested with a Siemens MC35i) or a cellphone with modem capabilities supported by Linux (I don’t have that)
- Gammu

Set up the modem :

Connect the GSM modem to the Nagios machine through the serial port and make sure it receives signal from the carrier (LED blinking slowly means everything is OK, if not it blinks fast)

Install and configure Gammu :

# apt-get install gammu

The modem should be accessible through /dev/ttyS0

# vim /etc/gammurc

port = /dev/ttyS0
connection = at19200
startinfo = no
name = Siemens
synchronizetime = no
use_locking = no

Test the modem

# gammu --identify
Manufacturer : Siemens
Model : unknown (MC35i)
Firmware : REVISION 02.00
IMEI : 3515590XXXXXX
Product code : MC35i


# gammu --networkinfo
Network state : home network
Network : 206 10 (Mobistar, Belgium), LAC 6B08, CID 19EC
Name in phone : "B mobistar"

# gammu --monitor 1
Press Ctrl+C to break...
Entering monitor mode...

Enabling info about incoming SMS : No error.
Enabling info about incoming CB : No error.
Enabling info about calls : No error.

Enabling info about USSD : No error.
SIM phonebook : 59 used, 41 free
Dialled numbers : 7 used, 3 free
Received numbers : 0 used, 10 free
Missed numbers : 0 used, 10 free

Own numbers : 1 used, 2 free
Phone phonebook : 0 used, 250 free
Leaving monitor mode...

Everything looks fine !

Before we continue, let’s check permissions on /dev/ttyS0

# ls -l /dev/ttyS0
crw-rw---- 1 root dialout 4, 64 jan 5 16:14 /dev/ttyS0

Nagios is usually running as user “nagios”, so any notification command would be executed as “nagios”. We can see user nagios wouldn’t have permissions to access devices connected to /dev/ttyS0.

We’ll apply the SUID bit (set-UID) on the command in charge of sending SMS notifications, this will execute gammu on behalf of user root.

# chmod 4755 /usr/bin/gammu

We could put nagios in the dialout group as well. I didn’t as Nagios is running on an isolated box in the LAN.
If someone is able to mess up with gammu executed as SUID on that box, that would mean I’m already in a lot of troubles anyway :-)

Before we continue, we’ll try to send a SMS to the belgian cell number 0475123456

# echo "test" | gammu --sendsms TEXT 0475123456
If you want break, press Ctrl+C...
Sending SMS 1/1....waiting for network answer..OK, message reference=181

It worked.

Now, an example of Nagios config for SMS notifications :

define command{
command_name host-notify-by-sms
command_line /usr/bin/printf "%b" "NAGIOS / Host: "$HOSTNAME$" / State: $HOSTSTATE$ / Info:$HOSTOUTPUT$ / Date:$SHORTDATETIME$" | /usr/bin/gammu --sendsms TEXT $CONTACTPAGER$


define command{
command_name notify-by-sms
command_line /usr/bin/printf "%b" "NAGIOS / Host: "$HOSTALIAS$" / State: $SERVICESTATE$ / Info:$SERVICEOUTPUT$ / Date:$SHORTDATETIME$" | /usr/bin/gammu --sendsms TEXT $CONTACTPAGER$


define contact{
contact_name email
alias email
service_notification_period 24x7
host_notification_period 24x7

service_notification_options c,r
host_notification_options d,r
service_notification_commands notify-by-email
host_notification_commands host-notify-by-email


define contact{
contact_name sms
alias sms
service_notification_period smshours
host_notification_period smshours

service_notification_options c,r
host_notification_options d,r
service_notification_commands notify-by-sms
host_notification_commands host-notify-by-sms
pager 0475123456


define contactgroup{
contactgroup_name admins
alias Nagios Administrators
members email, sms

define timeperiod{
timeperiod_name smshours
alias SMS Hours
sunday 00:00-24:00
monday 00:00-07:00,18:00-24:00
tuesday 00:00-07:00,18:00-24:00

wednesday 00:00-07:00,18:00-24:00
thursday 00:00-07:00,18:00-24:00
friday 00:00-07:00,18:00-24:00
saturday 00:00-24:00

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