Dynamic DNS

Dynamic DNS

Overview

Dynamic DNS (DDNS) is a service that automatically updates a domain name system (DNS) to point to a changing IP address, typically used for residential or small business networks with dynamic IP addresses. This allows users to access their home or office network via a consistent domain name, even when their ISP frequently changes their IP address.

Common Dynamic DNS Tools

Several tools and services are commonly used for implementing Dynamic DNS, including:

• Dnsmasq (often used combined with other DNS forwarding tools)
• DuckDNS (a free, popular DDNS service)
• No-IP (a widely used free and paid service)
• Dynu
• DynDNS (now part of Oracle)

For this guide, we will focus on tools that are typically installed on local Linux servers or routers.

Installation and Configuration

1. Installing ddclient

One of the most common tools for DDNS on Linux is ddclient, a Perl-based client for updating dynamic DNS entries.

• Installation:

<syntaxhighlight lang="bash"> sudo apt update sudo apt install ddclient </syntaxhighlight>

• Configuration:

The configuration file is usually located at /etc/ddclient.conf. Here is a sample configuration for using No-IP:

protocol=dyndns2
use=web
server=dynupdate.no-ip.com
login=your-username
password=your-password
yourdomain.no-ip.org

2. Configuring the Service

After editing /etc/ddclient.conf, ensure ddclient runs on startup and is properly configured: <syntaxhighlight lang="bash"> sudo systemctl enable ddclient sudo systemctl restart ddclient </syntaxhighlight>

3. Router-based DDNS

Many consumer routers have built-in support for DDNS services like DynDNS, No-IP, and DuckDNS. The setup generally involves:

• Logging into the router’s web interface
• Navigating to the DDNS configuration section
• Selecting your DDNS provider
• Entering your account credentials
• Saving the configuration

This approach offloads the update task to the router, removing the need for a local client.

Verifying Configuration

To verify that your DDNS configuration is working:

• See if your DNS name resolves to your current IP (via ping or nslookup)
• Check the log file (/var/log/ddclient.log or system journal)
• Use online tools to verify DNS resolution

Tips & Troubleshooting

• Ensure your firewall permits update traffic
• Check that your DNS provider supports dynamic update protocols
• Use verbose or debug mode in ddclient (-verbose -debug) for troubleshooting
• Consider setting up redundancy with multiple DDNS providers

Security Considerations

• Use encrypted protocols when possible
• Protect your configuration files
• Use strong passwords

Conclusion

Dynamic DNS is an invaluable tool for remote access to networks with changing IP addresses. Proper installation and configuration ensure seamless connectivity and minimal disruptions.

For more detailed instructions or specific provider configurations, consult the respective service documentation or your network administrator.

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This article provides an extensive overview of Dynamic DNS and its setup. This information was added to the wiki page at the following URL: https://wiki.h4ks.com/index.php/Dynamic_DNS