dyndns-bash

This codebase consists of a Bash shell script with which to update a specified DNS A (alias) record contained within a specified AWS Route53 DNS zone with an optionally specified TTL (time-to-live) value (in seconds).

Requirements

Network requirements:

DNS resolution and reachability of one or more of the following domains is required (or alteration of this script to provide alternative method):

• https://checkip.amazonaws.com/
• https://api.ipify.org?format=text
• https://api.my-ip.io/ip.txt

Keep in mind these services have their own terms of service; modify the IP_FUNCS array to select which ones you want.

Software dependencies

Rough list of software required:

• Bash
• curl
• AWS CLI

This was developed with the following versions initially:

• GNU bash, version 4.4.20(1)-release (x86_64-pc-linux-gnu)
• curl 7.58.0 (x86_64-pc-linux-gnu) libcurl/7.58.0 OpenSSL/1.1.1i zlib/1.2.11 libidn2/2.3.0 libpsl/0.19.1 (+libidn2/2.0.4) nghttp2/1.30.0 librtmp/2.3
• OpenSSL 1.1.1i 8 Dec 2020
• aws-cli/1.14.44 Python/3.6.9 Linux/4.4.0-19041-Microsoft botocore/1.16.19

AWS permissions

The AWS principal(s) being used must have the route53:ChangeResourceRecordSets permissions for any DNS zones you wish to modify.

Example IAM Policy:

{
   "Version": "2012-10-17",
   "Statement": [
       {
           "Sid": "allow-dyndns-bash",
           "Effect": "Allow",
           "Action": "route53:ChangeResourceRecordSets",
           "Resource": "arn:aws:route53:::hostedzone/<YOUR_ZONE_ID_HERE>"
       }
   ]
}

Invocation

Syntax:

bash dyndns.bash "<zone_id>" "<record_name> [ttl]"

For example:

bash dyndns.bash "XYZROUTE53ZONEID" "test.example.com"

Configuration

To provide AWS credentials, use environment or file-driven AWS CLI configuration as documented by Amazon.