There are services such as SiteUptime that will do this for you out of the box, however there are efficient, free ways of doing this yourself.

Prerequisites:
1. You have permission to create and run bash (shell) scripts on your server.
2. You have permission to create and schedule cronjobs on your server.
3. You have permission to send emails from your server.

Ok, let’s get started.

1. Create a file on your server called monitorsites.sh (the location doesn’t matter, however I recommend keeping it outside of publicly accessible folders).
2. In monitorsites.sh, paste the following:

#!/bin/bash

SITESFILE=sites.txt #list the sites you want to monitor in this file
EMAILS="you@email.com,someoneelse@email.com" #list of email addresses to receive alerts (comma separated)

while read site; do
    if [ ! -z "${site}" ]; then
        
        CURL=$(curl -s --head $site)
        
        if echo $CURL | grep "200 OK" > /dev/null
        then
            echo "The HTTP server on ${site} is up!"
        else    

            MESSAGE="This is an alert that your site ${site} has failed to respond 200 OK."

            for EMAIL in $(echo $EMAILS | tr "," " "); do
                SUBJECT="$site (http) Failed"
                echo "$MESSAGE" | mail -s "$SUBJECT" $EMAIL
                echo $SUBJECT
                echo "Alert sent to $EMAIL"
            done      
        fi
    fi
done < $SITESFILE

4. Create a file named sites.txt in the same folder as monitorsites.sh. In this file, create a list of complete URLs you wish to monitor.

http://www.google.com
http://www.axertion.com
http://someotherwebsite.com

5. Test the script. Login to your server using SSH, and run the bash file using the following command:
sh monitorsites.sh

6. If done correctly, you will see something like this:

The HTTP server on http://www.google.com is up!
The HTTP server on http://www.axertion.com is up!
http://someotherwebsite.com (http) Failed
Alert sent to you@email.com
Alert sent to someoneelse@email.com

7. To have this script run automatically (say every 5 minutes), you can setup a cronjob. You can read more on how to do this by reading HowTo: Add Jobs To cron Under Linux or UNIX

Once setup, your cronjob will run at the interval you set, and you will receive an email if your site doesn’t response.

Keep in mind, if your sites are on the same server as this script runs and the cause of downtime is your server going down, you may not receive the alert email. This should alert you if your apache (httpd) process fails as this script does not rely on that process to run.

You can, however, use an SSH Tunnel to access your database remotely through a rackspace cloud server instance.  Here’s how.

Prerequisites

• You must have a Rackspace Cloud Server Instance with SSH Access
• You must have a Rackspace Cloud Database Instance, with a Database, User & Password assigned to it.

Step 1:  Connect to Cloud Server from PC

First, we must connect to our Cloud Server using SSH to store the server host key locally. To do this, do the following:

1. Download plink.exe and save it to your C:\ drive.
2. Open up Command Prompt, and do the following commands:
   Replace [CLOUD SERVER IP ADDRESS] with the IP address of your cloud server.
   

   cd C:\
   plink.exe -L 3307:[CLOUD SERVER IP ADDRESS]:3306 root@[CLOUD SERVER IP ADDRESS]
   

3. After completing the above commands, you will most  likely see a message saying “The server’s host key is not cached….”
   Enter y when it asks Store key in cache?
4. When prompted for a password, Enter your Cloud Server root user password.
5. You should now be connected to your cloud server using an SSH connection.

Step 2: Connect Using MySQL Management Software

Now we should be able to connect using a MySQL management tool such as HeidiSQL, which is a completely free solution that offers SSH Tunneling.

1. Download & Install  HeidiSQL
2. Open HeidiSQL and go to the Session Manager.
3. Create a New Session clicking the New button
4. On the Settings tab, enter the following:
   Network Type: SSH Tunnel
   Hostname/IP: [HOSTNAME OF CLOUD DATABASE INSTANCE]
   User: [CLOUD DATABASE USERNAME]
   Password: [CLOUD DATABASE PASSWORD]
   Port: 3307
   Uncheck Compressed client/server protocol
   Databases: [CLOUD DATABASE NAME(S)] –  comma separated if more than one database.
5. On the SSH Tunnel tab, enter the following:
   plink.exe location: Download plink.exe, and point this to it’s location
   SSH Host + port: [CLOUD SERVER HOSTNAME or IP]
   Username: [CLOUD SERVER SSH USERNAME]
   Password: [CLOUD SERVER SSH PASSWORD]
   Private Key File: Not needed, leave blank.
   Local Port: 3307
6. Click the Open button at the bottom. You should now be connected to your cloud database.