Before setting up Nagios SMS alerts, ensure you have:

• Nagios Core or XI installed (version 3.x or later recommended)
• Server with outbound email capability (SMTP)
• SMS gateway service (e.g., Twilio, Nexmo, or carrier-specific email-to-SMS)
• Basic understanding of Nagios configuration files

The most common method uses your mobile carrier's email-to-SMS address format. Example for US carriers:

# Example contacts.cfg entry
define contact {
    contact_name                    sms_admin
    alias                           System Admin
    service_notification_period     24x7
    host_notification_period        24x7
    service_notification_options    w,u,c,r
    host_notification_options       d,u,r
    service_notification_commands   notify-service-by-sms
    host_notification_commands      notify-host-by-sms
    email                           [email protected]@txt.att.net  # AT&T format
}

For more reliable delivery, integrate Twilio's API:

#!/bin/bash
# /usr/local/nagios/libexec/sms_notify.sh

# Twilio credentials
ACCOUNT_SID="YOUR_ACCOUNT_SID"
AUTH_TOKEN="YOUR_AUTH_TOKEN"
FROM_NUMBER="+15551234567"
TO_NUMBER="+15559876543"

# Nagios variables
MESSAGE="$1"

# Send via curl
curl -X POST "https://api.twilio.com/2010-04-01/Accounts/$ACCOUNT_SID/Messages.json" \
--data-urlencode "Body=$MESSAGE" \
--data-urlencode "From=$FROM_NUMBER" \
--data-urlencode "To=$TO_NUMBER" \
-u "$ACCOUNT_SID:$AUTH_TOKEN"

Then define the command in commands.cfg:

define command {
    command_name    notify-service-by-sms
    command_line    /usr/local/nagios/libexec/sms_notify.sh "Nagios - $NOTIFICATIONTYPE$ - $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$"
}

Key verification steps:

1. Test the SMS script manually from command line
2. Check Nagios debug logs (/usr/local/nagios/var/nagios.log)
3. Verify notification intervals in timeperiods.cfg
4. Confirm contact group assignments

Other reliable methods include:

• Pushover: Mobile push notifications with dedicated app
• PagerDuty: Enterprise-grade alerting with on-call scheduling
• Telegram/Slack bots: For teams already using these platforms

Before configuring mobile alerts in Nagios, ensure you have:

• Nagios Core 4.x+ or Nagios XI installation
• SMS gateway service (like Twilio, Nexmo, or local provider)
• Server with outbound internet access
• Basic knowledge of Nagios command/config files

Here are three common approaches to enable SMS notifications:

1. Using Email-to-SMS Gateways

# Sample configuration in commands.cfg
define command {
    command_name notify-host-by-sms
    command_line /usr/bin/printf "%b" "***** Nagios *****\nNotification Type: $NOTIFICATIONTYPE$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\nDate/Time: $LONGDATETIME$" | /bin/mail -s "** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is $HOSTSTATE$ **" $CONTACTPAGER$
}

Then map your provider's email-to-SMS address (e.g., 1234567890@txt.att.net for AT&T) to the contact's pager field.

2. Direct API Integration (Twilio Example)

# Create /usr/local/bin/send_sms_twilio
#!/bin/bash
TWILIO_ACCOUNT_SID="YOUR_SID"
TWILIO_AUTH_TOKEN="YOUR_TOKEN"
TWILIO_NUMBER="+15556667777"

curl -X POST "https://api.twilio.com/2010-04-01/Accounts/$TWILIO_ACCOUNT_SID/Messages.json" \
--data-urlencode "Body=$1" \
--data-urlencode "From=$TWILIO_NUMBER" \
--data-urlencode "To=$2" \
-u "$TWILIO_ACCOUNT_SID:$TWILIO_AUTH_TOKEN"

Make it executable (chmod +x /usr/local/bin/send_sms_twilio) and configure Nagios command:

define command {
    command_name notify-by-twilio-sms
    command_line /usr/local/bin/send_sms_twilio "$NOTIFICATIONTYPE$ alert for $HOSTNAME$/$SERVICEDESC$: $SERVICESTATE$" $CONTACTPAGER$
}

define contact {
    contact_name                    jdoe-sms
    alias                           John Doe (SMS)
    service_notification_period     24x7
    host_notification_period        24x7
    service_notification_options    w,u,c,r
    host_notification_options       d,u,r
    service_notification_commands   notify-by-twilio-sms
    host_notification_commands      notify-by-twilio-sms
    email                           jdoe@example.com
    pager                           +15551234567  # Must include country code
}

• Test notifications manually first by running the script from CLI
• Check Nagios debug logs (tail -f /usr/local/nagios/var/nagios.log)
• Verify SMS gateway API credentials and rate limits
• Ensure timeouts don't block Nagios (consider async notifications)

For teams using mobile apps like Nagios XI Mobile or integrating with PagerDuty/AlertOps:

# Sample webhook integration
define command {
    command_name notify-service-by-push
    command_line /usr/bin/curl -X POST -H "Content-Type: application/json" -d '{"nagios_host":"$HOSTNAME$","service":"$SERVICEDESC$","state":"$SERVICESTATE$","output":"$SERVICEOUTPUT$"}' https://your.mobilegateway.com/api/v1/alerts
}