Hello. I was a Linode customer from 2003 to 2006. Now I'm considering moving back - I love everything about Linode except the puny disk space, but I'm starting to feel willing to overlook that to get all the rest of the goodness that comes along with a Linode.

One feature I would love to see is dynamic DNS capabilities like zoneedit's. Others have asked for this but I've never seen a response from the Linode.com staff.

Using zoneedit's dynamic dns feature is pretty simple: you just wget a special URL and the request causes an update to the IP address of an entry in your DNS. I have my home server set up to hit this address each time the network comes up.

It woud be great if Linode DNS could do this; unless it can, I will stick with zoneedit. But I'd be much happier to be able to use Linode.com's DNS as well.

I don't use Linode's DNS myself, but surely it's possible to implement that with a bit of Perl. As long as there isn't a CAPTCHA.

This would be pretty easy to get working using the API.

Take a look at the API doc at http://www.linode.com/api

The request would look something like this (I haven't tested this):

https://api.linode.com/?api_key=abc123& ... et=1.1.1.1

Not quite wget, but the Linode API does let you update your DNS resources, so it shouldn't be too hard to script an update process for your home machine.

Alternatively, for maximum flexibility one thing you could consider would be hosting the DNS zone master yourself on your Linode, and then have the Linode DNS configuration slave off of your Linode. This gives you complete control over your zone and you can implement whatever dynamic update methods or features you want yourself, while retaining the redundancy and availability of the the Linode servers.

-- David

Thanks for the info - I was unaware that the Linode API would support this. I will definitely investigate and if I come up with a general solution, I will post about it in the forms so that others can do the same.

OK, so the one feature that I think is missing is a parameter for domain.resource.update, something like "UseRequesterIpAsTarget". This parameter would specify that the requesting client's IP address should be used as the target. This is what zoneedit does - you just hit a URL with wget and whatever IP address you came from is used as the IP address for the host in the DNS record.

This is useful because sometimes a client doesn't actually know what its public IP address is. For example, in my home setup, the box in question is NAT'd behind a cable modem that I use port forwarding on to forward ports I care about. My box doesn't actually know what the public IP address of the cable modem is, but since the box is NAT'd by the cable modem, any traffic it initiates will have the cable modem's IP.

Also, as an aside - I appreciate that the Linode API exists, but it really needs to be documented better. The parameters for the request are almost completely undocumented, although often their names "suggest" what they are used for, and the formatting of the Linode API on the web page makes it very difficult to read. To summarize: great API, crappy documentation. Please fix.

While some option to use the requestor's IP would be easiest, this is nothing that couldn't be solved with some creative scripting.

Use this to get your public IP:

lynx -dump http://www.formyip.com/ | awk "/IP is/{print $NF}"|egrep -o '[0-9.]+'

Thank you for the tip. I will use such an idea if Linode isn't willing to or can't implement the feature I have requested. I sure hope Linode does though as it would be nice if everyone can benefit from a single, easy solution to this problem.

The automation page linked here: http://whatismyip.com/automation/default.asp will return nothing but you external IP address.

BTW, I was playing around, here is a way to put it all into just one simple command.

wget -qO- "https://api.linode.com/?api_key=abc123&api_action=domain.resource.update&DomainID=5101&ResourceID=18131&Target=`wget -qO- whatismyip.org`"

You can wait and hope Linode develops a solution for you, but if I were you I'd just implement one of the solutions here and be done with it.

Another option is to use Linode for its hosting and DNS services and use a dynamic DNS provider for the home system.

As an example, lets say the home system has a host name of "bji.dyndns.org" and the home system uses a standard dynamic DNS updater either on the server or your router to keep DynDNS update to date with the address. Using "mydomain.tld" as an example domain, you can create a CNAME record such as "virtual" (virtual.mydomain.tld) that references "bji.dyndns.org".

Sample DNS Entries

mydomain.tld - A Record - (Linode IP address)
www.mydomain.tld - A Record - (Linode IP address)
virtual.mydomain.tld - CNAME Record - bji.dyndns.org

That is a great idea. I researched dyndns but they don't make keeping your dynamic host entry up-to-date any easier than using Linode's API for this purpose in its current form would. dyndns requires that you run an "update client" to update your DNS entry. What I want is something as brain dead simple and elegant as the zoneedit technique of "wget a URL and you're done".

Do you know of another free dynamic DNS provider that supports a zoneedit style of updates?

I still think that this would best and easiest be covered by a simple addition to the Linode DNS API ...

What I'd actually do is wait on moving my DNS over to Linode, and leave it on zoneedit. This would make me less happy with Linode service, but not unhappy enough to ditch Linode. But I want to be happy, so I'd prefer that Linode implement this eminently sensible addition to their Linode DNS API!

While they offer clients, I'm pretty sure you can get away with a pure HTTP request manually if you want to. I know I used to do that just with a shortcut in my browser before I gave control over to maintaining the address to my local router (Linksys+Tomato).

It's been a while since I used it, but I've still got the shortcut, and it looks like:

http://user:password@members.dyndns.org/nic/update?system=dyndns&hostname=xxxx.yyyy&wildcard=NOCHG

Ah, yeah - see http://www.dyndns.com/developers/specs/syntax.html

-- David[/code]

Keep in mind though, DynDNS can ban you if you make updates when the IP hasn't changed, so don't make a cron job out of it. Also, they will erase your domain if there's no changes after I believe 30 days.

There's some pre-made shell scripts that take both things into consideration here.