Dynadot Dynamic DNS (DDNS) Setup

This page documents how to configure Dynamic DNS for Dynadot and automatically update the A record when the public IP address changes.

Requirements

Dynadot account
Domain using Dynadot DNS
DDNS password generated in Dynadot
Ubuntu server with outbound HTTPS access

Dynadot configuration

1. Enable Dynadot DNS

Log in to Dynadot
Go to My Domains
Click the domain
Set DNS → Dynadot DNS

2. Enable Dynamic DNS

Domain settings → Dynamic DNS
Enable DDNS
Generate a DDNS password
Save it securely

3. Required values

Field	Example
Domain	example.com
Subdomain	@ or www
Record type	A (IPv4) or AAAA (IPv6)
DDNS password	(generated in Dynadot)

Dynadot update endpoint

Dynadot accepts HTTP GET updates:

https://www.dynadot.com/set_ddns

Parameters:

domain
subDomain
type
ip
pwd
ttl (optional)

Ubuntu auto-update script

Script: dynadot-ddns.sh

nano .env

Add this:

# SUBDOMAIN should be left empty if root domain.
DOMAIN=<domain>
SUBDOMAIN=
TYPE=A
PASSWORD=YOUR_DYNADOT_PASSWORD
TTL=300

chmod 600 .env

#!/bin/bash

# ===== CONFIG =====
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
ENV_DDNS="$SCRIPT_DIR/.env"                # Dynadot settings
ENV_DISCORD="$SCRIPT_DIR/../bots/discord/.env"  # Discord bot settings
IP_FILE="$SCRIPT_DIR/dynadot_last_ip.txt"
LOG_FILE="$SCRIPT_DIR/log.txt"
LOG_ROTATED="$SCRIPT_DIR/log.txt.1"

# ===== LOG ROTATION =====
if [ -f "$LOG_FILE" ]; then
    mv -f "$LOG_FILE" "$LOG_ROTATED"
fi

# ===== LOAD ENV =====
# Dynadot settings
if [ -f "$ENV_DDNS" ]; then
    export $(grep -v '^#' "$ENV_DDNS" | xargs)
else
    echo "ERROR: Dynadot .env not found at $ENV_DDNS"
    exit 1
fi

# Discord bot settings
if [ -f "$ENV_DISCORD" ]; then
    export $(grep -v '^#' "$ENV_DISCORD" | xargs)
else
    echo "ERROR: Discord .env not found at $ENV_DISCORD"
    exit 1
fi

# ===== CHECK REQUIRED ENV VARIABLES =====
for var in DOMAIN PASSWORD TTL DISCORD_BOT_TOKEN LOGS_CHANNEL_ID; do
    if [ -z "${!var}" ]; then
        echo "ERROR: $var not set in .env files"
        exit 1
    fi
done

CHANNEL_ID="$LOGS_CHANNEL_ID"

# ===== LOG FUNCTION =====
log() {
    echo "$(date '+%Y-%m-%d %H:%M:%S') - $1" >> "$LOG_FILE"
}

# ===== DISCORD FUNCTION =====
send_discord() {
    local result="$1"
    local ip_old="$2"
    local ip_new="$3"
    local timestamp
    timestamp=$(date -u +"%Y-%m-%dT%H:%M:%SZ")  # ISO 8601 UTC

    local json_payload=$(cat <<EOF
{
  "content": "The domain name #${DOMAIN} dynamically resolves to ${result}.",
  "embeds": [
    {
      "description": "Domains: ${DOMAIN}\nResult: ${result}\nOld IP: ${ip_old}\nNew IP: ${ip_new}\nTime: ${timestamp} UTC",
      "color": 15258703,
      "author": { "name": "DDNS" },
      "footer": { "text": "DDNS ${result}" }
    }
  ]
}
EOF
)

    curl -s -H "Authorization: Bot $DISCORD_BOT_TOKEN" \
         -H "Content-Type: application/json" \
         -X POST \
         -d "$json_payload" \
         "https://discord.com/api/v9/channels/${CHANNEL_ID}/messages" > /dev/null
}

log "---- Script started ----"

# ===== GET CURRENT IP =====
CURRENT_IP=$(curl -s https://checkip.amazonaws.com)
if [ -z "$CURRENT_IP" ]; then
    log "ERROR: Could not fetch public IP"
    send_discord "ERROR" "N/A" "N/A"
    exit 1
fi
CURRENT_IP=$(echo "$CURRENT_IP" | tr -d '[:space:]')
log "Current IP: $CURRENT_IP"

# ===== READ LAST IP =====
if [ -f "$IP_FILE" ]; then
    LAST_IP=$(cat "$IP_FILE")
else
    LAST_IP=""
    touch "$IP_FILE"
    log "Created IP file"
fi
log "Last IP: $LAST_IP"

# ===== COMPARE =====
if [ "$CURRENT_IP" = "$LAST_IP" ]; then
    log "IP unchanged. No update needed."
    exit 0  # No Discord notification if unchanged
fi

# ===== UPDATE DYNDOT =====
SUBDOMAIN=${SUBDOMAIN:-""}  # default to empty if not set
TYPE=${TYPE:-"A"}           # default to A record
UPDATE_URL="https://www.dynadot.com/set_ddns?containRoot=true&domain=${DOMAIN}&subDomain=${SUBDOMAIN}&type=${TYPE}&ip=${CURRENT_IP}&pwd=${PASSWORD}&ttl=${TTL}"
RESPONSE=$(curl -s "$UPDATE_URL")
log "Dynadot response: $RESPONSE"

# ===== SAVE IP & DISCORD =====
if echo "$RESPONSE" | grep -qi "success"; then
    echo "$CURRENT_IP" > "$IP_FILE"
    log "IP updated and saved."
    send_discord "SUCCESS" "$LAST_IP" "$CURRENT_IP"
else
    log "ERROR: Dynadot update failed."
    send_discord "FAIL" "$LAST_IP" "$CURRENT_IP"
fi

log "---- Script finished ----"
echo

Installation

1. Save script

sudo nano /usr/local/bin/dynadot-ddns.sh

Paste script and edit variables.

2. Make executable

sudo chmod +x /usr/local/bin/dynadot-ddns.sh

3. Test manually

/usr/local/bin/dynadot-ddns.sh

4. Add cron job (every 5 minutes)

crontab -e

Add:

*/5 * * * * /usr/local/bin/dynadot-ddns.sh

Security notes

Store DDNS password securely
Limit file permissions
Do not commit the script to public repositories

References

Dynadot Help – Dynamic DNS
Dynadot API documentation