aws-dynDNS

This is a simple bash script that obtains the Public ip and updates a record in AWS, emulating DynamicDNS services

It is best ran as a cron (The interval depends on your requirements)

Requirements

jq

apt-get install jq

AWS Cli

apt-get install awscli

AWS Requirements

Create a Hosted Zone within AWS:

https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/CreatingHostedZone.html

(The current price per hosted zone is $0.50, or $0.10 if you already have more than 25 hosted zones)

Create an IAM user with Route53 permissions The AmazonRoute53FullAccess policy is the easiest option

Usage

Usage: aws-dyndns [OPTIONS]
  -h                   - help
  -z <zone_domain>     - AWS Zone domain name
  -r <record_value>    - Record value eg. home
  -c                   - create record if it doesn't exist
  -p <aws_profile>     - AWS Profile (defaults to default)

Recommended setup

I have this installed on a Raspberry Pi, as it's a cheap little device that can be left running 24/7

Initial setup on the Raspberry Pi (or other compatible host)

Create the directory ~/.aws

$ mkdir ~/.aws

Create/Edit the ~/.aws/config file

$ vim ~/.aws/config
[default]
region=<your-default-region>
cli_follow_urlparam=false

Replace <your-default-region> with your preferred region

Create/Edit the ~/.aws/credentials file

$ vim ~/.aws/credentials
[aws-dyndns]
aws_access_key_id=xxxxxxx
aws_secret_access_key=xxxxxxx

Enter the aws_access_key_id and aws_secret_access_key generated when you created the IAM user

Clone this repo

git clone git@github.com:Stretch96/aws-dynDNS
cd aws-dynDNS

Add a symlink from the aws-dyndns script to /usr/local/bin:

ln -s aws-dyndns /usr/local/bin/aws-dyndns

Testing the setup

Once you have created a Hosted Zone on AWS, the following command should produce an error:

(Replace <hosted_zone_name> with your Hosted Zone domain name)

$ aws-dyndns -z <hosted_zone_name> -r test123 -p aws-dyndns
Error: test record doesn't exist in <hosted_zone_name> zone
       Either create the record first in AWS,
       or add the -c flag to create it

If any other error appears, there may be something wrong with the setup

Now run the same command, but with the -c flag, which should create the record:

$ aws-dyndns -z <hosted_zone_name> -r test123 -c -p chris_qa_dns
Creating record
Record <hosted_zone_name> updated to <your-public-ip> - Status: PENDING

If anything other than PENDING for the Status is produced, something has gone wrong

Creating the cronjob

Decide what DNS record you would like to be created to point towards your public IP address, eg. home

The following configuration will run the script every 5 minutes

Warning: This script uses the ipinfo.io service to obtain the Public ip ipinfo.io currently have a Free rate limit of 50,000 requests per day If you require more than this, consider creating a paid account: https://ipinfo.io/pricing (For reference, there are 1440 minutes in a day)

Create/Edit the file /etc/cron.d/aws-dyndns: (Replace <username> with the user that the cron should run as) (Replace <hosted_zone_name> with your Hosted Zone domain name)

$ vim /etc/cron.d/aws-dyndns
*/5 * * * * <username> /usr/local/bin/aws-dyndns -z <hosted_zone_name> -r home -c -p aws-dyndns | /usr/bin/logger -t aws-dyndns

Check /var/log/syslog for any errors

tail -f /var/log/syslog

Every 5 minutes, you should see something like:

Nov 28 21:00:01 raspberrypi CRON[1234]: (<username>) CMD (/usr/local/bin/aws-dyndns -z <hosted_zone_name> -r home -c -p aws-dyndns | /usr/bin/logger -t aws-dyndns)

If it needs to create the record, you will see:

Nov 28 21:00:01 raspberrypi CRON[1234]: (<username>) CMD (/usr/local/bin/aws-dyndns -z <hosted_zone_name> -r home -c -p aws-dyndns | /usr/bin/logger -t aws-dyndns)
Nov 28 21:00:11 raspberrypi aws-dyndns: Creating record
Nov 28 21:00:16 raspberrypi aws-dyndns: Record <new-record-name> updated to <public-ip> - Status: PENDING

If your Public ip changes, it will produce the output:

Nov 28 21:00:01 raspberrypi CRON[1234]: (<username>) CMD (/usr/local/bin/aws-dyndns -z <hosted_zone_name> -r home -c -p aws-dyndns | /usr/bin/logger -t aws-dyndns)
Nov 28 21:00:16 raspberrypi aws-dyndns: Record <new-record-name> updated to <public-ip> - Status: PENDING

Confirming DNS record creation

Just run the following command and it should produce your Public ip:

$ host <domain-name>
1.2.3.4 # (Your Public ip address)

It may take a minute or two to update