#!/bin/bash
# Simple script to automatically update a DNS A record to point to your current
# IP address using the DirectAdmin API. Requires curl, dig and jq.
#
# There must already exist an A record for DNS_HOST, or this script will abort
# and complain about an invalid IP address.
#
# Based on <https://gist.github.com/DvdGiessen/b4203c69bf0c92f153ea05ed54d804c4>
################################################################################
# Configuration start
# The domain for the account in DirectAdmin
DOMAINNAME="some.domain.here"
# The hostname for your A record
DNS_HOST="myhost.some.domain.here"
# The URL to the DirectAdmin server we log in to
DA_URL="https://your.da.server:2222"
# The username and password for the account owning DOMAINNAME. Note that the
# password here should ideally be a Login Key that only has access to
# CMD_API_DNS_CONTROL and nothing else.
DA_USERNAME="username"
DA_PASSWORD="secret"
# Configuration end
################################################################################
# Validate an IP addres
#
# Returns 0 if IP is valid
# Returns 1 if IP is invalid
#
# Usage:
# validateIP IPADDRESS
# if [ ${?} -eq 0 ]; then
# echo good
# else
# echo bad
# fi
# OR
# if validateIP IPADDRESS; then
# echo good
# else
# echo bad
# fi
function validateIP() {
local ip=${1}
local validresult=1
# First check against a simple regex
if [[ ${ip} =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
# Then check each number
OIFS=${IFS}
IFS='.'
ip=(${ip})
IFS=${OIFS}
[[ ${ip[0]} -le 255 \
&& ${ip[1]} -le 255 \
&& ${ip[2]} -le 255 \
&& ${ip[3]} -le 255 ]]
validresult=${?}
fi
return ${validresult}
}
# Get the current IP address from DNS, and validate it.
CONFIGURED_IP="$(dig +short "${DNS_HOST}" A @$(dig +short "${DOMAINNAME}" NS | head -n1))"
if ! validateIP "${CONFIGURED_IP}"; then
echo "Invalid configured IP: ${CONFIGURED_IP}. Aborting." >&2
exit
fi
# Get current external IP address of this machine, and validate it.
CURRENT_IP="$(curl -s https://api.myip.com/ | jq -r .ip)"
if ! validateIP "${CURRENT_IP}"; then
echo "Invalid active IP: ${CURRENT_IP}. Aborting." >&2
exit
fi
# Check if the DNS A record needs to be updated
if [ "${CONFIGURED_IP}" != "${CURRENT_IP}" ]; then
# Update the DNS A record and report.
# TODO:
# * Change this to a POST?
RESULT="$(curl -sS -u "${DA_USERNAME}:${DA_PASSWORD}" "${DA_URL}/CMD_API_DNS_CONTROL?action=edit&domain=${DOMAINNAME}&arecs0=name%3D${DNS_HOST}.%26value%3D${CONFIGURED_IP}&type=A&name=${DNS_HOST}.&value=${CURRENT_IP}&json=yes")"
if [ "$(echo "${RESULT}" | jq -r .success)" == "Record Edited" ]; then
echo "$(date +"%F %T") DNS record updated: ${DNS_HOST} -> ${CURRENT_IP}"
else
echo "$(date +"%F %T") DNS record update failed" >&2
echo "${RESULT}" >&2
fi
fi
