Linode.com Forum

caker · Joined: 15 Apr 2003 Posts: 2386 Location: Galloway, NJ

Available now off the Member's Overview page is the Reverse DNS Configuration Manager (look near the "Network Information" button -- there is a link to it). It is fairly bare-bones at the moment, but get's the job done.

Requirements

Your reverse DNS hostname must first forward resolve to one of your IPs. I couldn't find any RFC's to back me up on this, but this is the way I want it. :twisted: After you perform the lookup in the RDNS Manager, it will present you with the option to make this the reverse for the IP address.

Delay and Propagation

We rebuild the zone files every 6 hours. ThePlanet syncs with our zones every hour. Hurricane Electric seems rather random, so I'll setup notifies for them.

Thanks, and enjoy!
-Chris

Quik · Joined: 17 Sep 2003 Posts: 124

This is absolutely fantastic Chris!

It is the first thing on my wish-list which I was about to post!

Great job :)

faded · Joined: 05 Jul 2003 Posts: 16 Location: Reno, Nevada

i must be missing something but i cannot edit my reverse all it does is show me what my current ip addresses reverse to if im missing something please tell me :lol:

vitre0us · Joined: 22 Jul 2003 Posts: 32 Location: Southern California

oooh nice :D

vitre0us · Joined: 22 Jul 2003 Posts: 32 Location: Southern California

faded wrote: i must be missing something but i cannot edit my reverse all it does is show me what my current ip addresses reverse to if im missing something please tell me :lol:

Set the ip address you want your host to resolve to in your name server, then when you type in the hostname in chris's script - it will do a lookup and use whichever linode ip it resolves into for the reverse dns...

i think i explained that okay 8)

caker · Joined: 15 Apr 2003 Posts: 2386 Location: Galloway, NJ

Cool -- here's an example:

Let's say your Linode has an IP address of 10.0.0.44, and you've registered "example.com" and have DNS serving it up somewhere.

You want "mylinode.example.com" to be the reverse for your IP.

First you've got to make mylinode.example.com resolve to 10.0.0.44 in your DNS server...

Then, go into the RDNS manager, lookup "mylinode.example.com" and it will perform a forward lookup. It finds that the hostname resolves to one of your IP addresses, and then asks you if you want to use it as the reverse for 10.0.0.44. You answer "Yes".

Done :-)

Make sense?

I need to put instructions on that page :-)

-Chris

schof · Joined: 18 Sep 2003 Posts: 46 Location: Los Angeles

...but there's one thing I don't understand about this feature -- why would I want to use it?

I use ZoneEdit to control my two domains; is this something I would use in addition to ZoneEdit or in replacement of it?

mikegrb · Posted: Thu Oct 23, 2003 11:09 am Post subject:

This would be in addition to zoneedit.com....

zoneedit is for forward resolving, going from name to ip. This is for reverse resolving, going from ip to name. For example type 'host <yourip>' and you should get a members.linode.com address.

schof · Joined: 18 Sep 2003 Posts: 46 Location: Los Angeles

mikegrb wrote: This would be in addition to zoneedit.com....

zoneedit is for forward resolving, going from name to ip. This is for reverse resolving, going from ip to name. For example type 'host <yourip>' and you should get a members.linode.com address.

So, again proving that my density approaches that of a black hole...why would I want to do this?

ZoneEdit sends everyone going to officemechanic.com (plus a few subdomains) to the IP of my linode.

What purpose does reverse resolving in this manner serve? I can understand using reverse DNS to track down spammers or something, but I already *know* what my IP and hostname are. What simple and obvious thing am I completely overlooking?

mikegrb · Posted: Thu Oct 23, 2003 11:24 pm Post subject:

Well IRC is one example. Just about any service with a log, http, ftp, ssh, etc generally has an option of doing a reverse lookup on IPs that connect for use in logs. Mail it can be used for by the server itself. For example to determine if that server really should be sending mail for that domain... though that last one if pushing it. They are useful for traceroutes as well because names are generally somewhat descriptive. I know there are many many more but there's a few to give you an idea.

caker · Joined: 15 Apr 2003 Posts: 2386 Location: Galloway, NJ

Anything that originates from your Linode originates from your IP address, not your domain names. The remote servers your Linode connects to might perform a reverse dns lookup on your IP, perhaps to place the resolved hostname inside the logs instead of just the raw IP (for example, apache's access_log can do this so webalizer doesn't have to).

Mail that goes through your Linode out to another provider will likely contain the reverse DNS hostname of your Linode in it's headers. By default, it would be the li[123]-[20-255].members.linode.com format. By customizing the reverse dns, I guess it looks more professional (not in some cases, see below), or more of a vanity thing. There are some instances where a correct or matching reverse-dns is required, but mostly you can get away with "just having one" in the first place.

IRC users like it because when they join a channel, it'll normally announce to the room "luser@my.dialup.isp.com has joined". But, connecting through their Linode with a custom reverse dns makes em look bad ass, for example: "caker@whos.got.a.bigantenna.com has joined". Cool, huh?

-Chris

neil · Joined: 31 Oct 2003 Posts: 4

Is it working properly?
Or is it just me having problems setting reverses...

Thanks.

jsbthree · Joined: 28 Feb 2005 Posts: 1

It was the answer to a vexing problem I was having. I'm not sure if its a bug in the Hula server but it has to have a reverse DNS in order to send mail. The reason this could be a bug in my opinion is that its not toched upon in the documentation. You'd think it would be mentioned somewhere. I found it by eliminating every other possible variable.

The only other thing I can reason out is that they didn't consider a hosting situation in which the reverse DNS was not automatically handeled or the same as the forward.. But that doesnt' much make sense to me. Anyone know?. :?: Anyone care better question? :P

sednet · Joined: 17 Mar 2004 Posts: 106 Location: Europe

jsbthree wrote: It was the answer to a vexing problem I was having. I'm not sure if its a bug in the Hula server but it has to have a reverse DNS in order to send mail. The reason this could be a bug in my opinion is that its not toched upon in the documentation. You'd think it would be mentioned somewhere. I found it by eliminating every other possible variable.

I've never used or even heard of Hula, but chances are your mailer doesn't need to have reverse DNS set in order to send mail. It's likely the other side of your mail sending that is causing you problems. I think most mailers will reject your mail if a lookup of your IP fails. I can't speak for every MTA but sendmail does this by default.

OverlordQ · Joined: 04 Jun 2004 Posts: 200

I got two IP's pointing to my box, but the Reverse DNS manager only works for one of them, is there any way to fix this?

New Feature - Reverse DNS Manager