Dynamic DNS and OpenWRT
Access a home server from anywhere using Dynamic DNS (DDNS).
My server sits behind a router assigned a dynamic IP address by the ISP. If I want to remotely connect to my server I can use a DDNS service to create a domain name that automatically updates the IP address whenever it changes and redirect traffic to the new location.
0. Select a DDNS service
I use the free DDNS service duckdns.org which permits the creation of up to 4 domains in the format
subdomain_foo.duckdns.org. Make note of duckdns.org/install (while logged in) for customized settings useful for configuring the router for DDNS.
1. Configure OpenWRT for notification
Different routers configure DDNS differently but the goal is the same: the ability to notify the DDNS service whenever the IP address assigned by the ISP is modified. I am using an OpenWRT-powered router and these are the steps to configure OpenWRT to use duckdns DDNS.
Login to the router and install DDNS packages …
opkg update opkg install luci-app-ddns ddns-scripts
Use the customized settings from duckdns.org/install to configure
config service "duckdns" option enabled "1" option service_name "duckdns.org" option domain "subdomain_foo" option username "NA" option password "string_of_letters_and_digits" option ip_source "network" option ip_network "wan" option force_interval "72" option force_unit "hours" option check_interval "10" option check_unit "minutes" option update_url "https://www.duckdns.org/update?domains=[DOMAIN]&token=[PASSWORD]&ip=[IP]" option use_syslog "1"
Start daemon …
sh . /usr/lib/ddns/dynamic_dns_functions.sh start_daemon_for_all_ddns_sections "wan" exit
LuCI interface the service is visible under
Services->Dynamic DNS. Navigate to
System->Startup and enable DDNS to ensure the router continues to send IP address changes after reboot and hotplug events.
Link: OpenWRT DDNS client
2. Port forwarding
Port forwarding configures OpenWRT to forward traffic directed at one of the router’s ports to the listening port on the server. Example: configure port
56789 on the router to connect over SSH to port
22 on the home server.
🐧 Part of the Linux Home Server project.