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Using cURL for Dynamic DNS Updates

cURL is a versatile command-line tool that can be used to update DNS records in Poweradmin. Here are various examples of using cURL with the Dynamic DNS update system.

When you are setting things up for the first time, append &verbose=1 to any URL below. The server then returns a human-readable status message ("Your hostname has been updated.", "Invalid username or password...") instead of a two-letter code, which makes misconfiguration much easier to spot. Drop the parameter once your client is working.

Basic Update Examples

Update IPv4 Address

curl -u username:password "https://dns.example.com/dynamic_update.php?hostname=host.example.com&myip=192.0.2.1"

Automatic IP Detection

curl -u username:password "https://dns.example.com/dynamic_update.php?hostname=host.example.com&myip=whatismyip"

Update IPv6 Address

curl -u username:password "https://dns.example.com/dynamic_update.php?hostname=host.example.com&myip6=2001:db8::1"

Advanced Usage

Combined Multiple IPv4 and IPv6 Update

# Update multiple A records and single AAAA record in one request
curl -u user:pass "https://yourhost/dynamic_update.php?hostname=host.example.com&myip=1.2.3.4,5.6.7.8&myip6=2001:db8::1&dualstack_update=1"

Dual-Stack Update

curl -u username:password "https://dns.example.com/dynamic_update.php?hostname=host.example.com&myip=192.0.2.1&myip6=2001:db8::1&dualstack_update=1"

Multiple IP Addresses

curl -u username:password "https://dns.example.com/dynamic_update.php?hostname=host.example.com&myip=192.0.2.1,192.0.2.2"

Using URL Parameters Instead of Basic Auth

curl "https://dns.example.com/dynamic_update.php?username=user&password=pass&hostname=host.example.com&myip=192.0.2.1"

Scripting Examples

Basic Update Script

#!/bin/bash
USERNAME="your_username"
PASSWORD="your_password"
HOSTNAME="your.hostname.com"
SERVER="https://dns.example.com/dynamic_update.php"

curl -s -u "$USERNAME:$PASSWORD" "$SERVER?hostname=$HOSTNAME&myip=whatismyip"

Periodic Update Script

#!/bin/bash
USERNAME="your_username"
PASSWORD="your_password"
HOSTNAME="your.hostname.com"
SERVER="https://dns.example.com/dynamic_update.php"
INTERVAL=300  # Update every 5 minutes

while true; do
    curl -s -u "$USERNAME:$PASSWORD" "$SERVER?hostname=$HOSTNAME&myip=whatismyip"
    sleep $INTERVAL
done

Error Handling

The update script returns HTTP status codes and messages that can be captured:

response=$(curl -s -w "%{http_code}" -u "$USERNAME:$PASSWORD" "$SERVER?hostname=$HOSTNAME&myip=whatismyip")
if [ $response -eq 200 ]; then
    echo "Update successful"
else
    echo "Update failed with code: $response"
fi

Security Considerations

  • Always use HTTPS to protect credentials
  • Consider using Basic Authentication instead of URL parameters
  • Store credentials securely, not in plain text
  • Use specific IP ranges if possible
  • Monitor for unusual update patterns