CDN and Load Balancer Tester

readme.md

CDN and Load Balancer Tester

This script checks the SSL installation and page title consistency across all the IP addresses resolved by a given domain. It can be used to test the configuration of CDNs (Content Delivery Networks) and load balancers.

Prerequisites

This script uses bash, curl, openssl and dig, make sure they are installed on your system before running the script.

Usage

To use the script, follow the steps below:

1. Save the script into a file named check.sh.
2. Make the script executable by running the command chmod +x check.sh.
3. Run the script with your domain as an argument: ./check.sh example.com.

How it Works

The script does the following for each IP address resolved from the given domain:

1. It checks if SSL is properly installed.
2. It fetches and prints the website title.

It only considers IP addresses in the resolution, CNAMEs are ignored.

The script prints an error message and exits with a non-zero status if SSL is not properly installed on an IP address, or if the titles from different IP addresses do not match.

Limitations

1. This script assumes that SSL is installed on port 443.
2. It expects the title to be on a single line and only one title per page.

License

This script is released under the MIT license.

check.sh

#!/bin/bash

if [ "$#" -ne 1 ]; then
    echo "Usage: ./check.sh [domain]"
    exit 1
fi

DOMAIN=$1
ALL_RECORDS=$(dig @8.8.8.8 +short $DOMAIN)

echo "resolving $DOMAIN"

# Filter only IP addresses
IPS=$(echo "$ALL_RECORDS" | grep -Eo '([0-9]{1,3}\.){3}[0-9]{1,3}')

echo "found following ip addresses resolved by $DOMAIN"
echo "$IPS"

previous_title=""
is_first=1
for IP in $IPS
do
    echo ""
    echo "testing $DOMAIN ($IP) ..."

    # Check if SSL is properly installed
    if echo | openssl s_client -servername $DOMAIN -connect $IP:443 2>/dev/null | \
        openssl x509 -noout > /dev/null 2>&1 ; then
        echo "SSL is properly installed"
    else
        echo "SSL is NOT properly installed"
        exit 1
    fi

    # Check website title
    title=$(curl -s -k --resolve $DOMAIN:443:$IP https://$DOMAIN | \
        grep -o '<title>.*</title>' | sed 's/<title>\(.*\)<\/title>/\1/')

    echo "<title>$title</title>"

    if ((is_first)) ; then
        previous_title=$title
        is_first=0
    elif [ "$previous_title" != "$title" ] ; then
        echo "website titles do not match"
        exit 1
    fi
done

echo ""
echo "all website titles match"