DNS-IP-Mapper

DNS-IP-Mapper is a tool designed to automatically assign available IP addresses from specified subnets to a list of FQDNs (Fully Qualified Domain Names).

Prerequisites

• Bash (version 4 or higher is recommended)
• host command (typically included in the bind-utils package)

Getting Started

1. Preparation

• FQDN File: Prepare a text file containing a list of FQDNs you wish to assign IP addresses to. Each FQDN should be on a new line.

  • Example: fqdns.txt

    db01.example.com
    db02.example.com
    web0[1-2].example.com
    

• Subnet File: Prepare another text file containing the subnets you want the IP addresses to be picked from. Each subnet should be on a new line.

  • Example: subnets.txt

    192.168.1.0/24
    192.168.2.0/24
    

2. Execute the Script

Run the script using the following command:

./assign_ips.sh -f <path_to_FQDN_file> -n <path_to_subnet_file> [-s <IP_start_range>] [-e <IP_end_range>]

Options

• -f : Path to the file containing FQDNs.
• -n : Path to the file containing subnets.
• -s : Starting IP address range (default is 1).
• -e : Ending IP address range (default is 240).

Example

./assign_ips.sh -f fqdns.txt -n subnets.txt -s 10 -e 100

This will attempt to assign IP addresses starting from .10 to .100 within the specified subnets to the FQDNs.

Output

The script will display the assigned IP addresses for each FQDN in the following format:

<fqdn>,<assigned_ip>

For example, the output might look something like:

db01.example.com,192.168.1.10
db02.example.com,192.168.1.11
web01.example.com,192.168.1.12
web02.example.com,192.168.1.13

IP Address Assignment Criteria

The script determines the availability of an IP address based on two checks:

1. DNS Check: The script checks if there's already a DNS record for the IP address using the host command.
2. Ping Check: The script then checks if the IP address responds to a ping.

An IP address is considered available for assignment if both checks fail, i.e., if there's no DNS record for the IP and it doesn't respond to a ping.

Note

• Currently, the script only supports CIDR values of 24, 23, and 22.
• In the current version, each FQDN is assigned a unique IP address from the provided subnets.