When you have a phone number assigned to you by the phone company, it doesn’t change on a daily or monthly basis. It’s static. It only changes when you relocate to a different service area. That’s because your phone number is designed to be used for incoming communications–for people to call you.
On the other hand, your cable modem or DSL may not have a static number (called an IP address). That’s because these connections were meant for outbound communications–you surfing the Internet. Most providers will assign you a static IP if you request one, usually for an extra charge that may not make it worth doing.
If you can’t or don’t want to get a static IP, but still need a static way to find your node, you can look into a dynamic DNS service. Most of these are free for a single address.
DD-WRT supports a number DNS services, and you find the Dynamic DNS (DDNS) setup under Setup >> DDNS. Click the images for a larger view.
I’ve used DynDNS.org for a while now. It’s very simple and stable, and is free for a single address. You sign up with DynDNS, and choose the url subdomain (“hostname”) you’d like to use–it will be something like myvpn.gotdns.org.
After you’ve signed up for a DDNS account, go back to your router’s DDNS settings and enter your account’s settings.
Typically, you will have a Dynamic type of account, and it will not be a Wildcard account. These are more advanced configurations, and typically don’t come with the free services. You’ll know if you need them, and you can always upgrade the day you do.
After configuring the DDNS settings, the router in a short time will update your account’s settings. On the client end, you now need to edit your OVPN configuration file, and put the host name where the IP address was, in the “remote” line. Now, even though your IP address may be reassigned periodically, you’ll always be able to use a static host name to locate your VPN.