Wildcard Subdomains

Question

I know there have been a few threads on this before, but I have tried absolutely everything suggested (that I could find) and nothing has worked for me thus far...

With that in mind, here is what I'm trying to do:

First, I want to allow users to publish pages and give them each a subdomain of their choice (ex: user.mysite.com). From what I can gather, the best way to do this is to map user.mysite.com to mysite.com/user with mod_rewrite and .htaccess - is that correct?

If that is correct, can somebody give me explicit instructions on how to do this?

Also, I am doing all of my development locally, using MAMP, so if somebody could tell me how to set up my local environment to work in the same manner (I've read this is more difficult), I would greatly appreciate it. Honestly, I have been trying a everything to no avail, and since this is my first time doing something like this, I am completely lost. Thanks so much for any help!

Update: Some of these answers have been REALLY helpful, but for the system I have in mind, manually adding a subdomain for each user is not an option. What I'm really asking is how to do this on the fly, and redirect wildcard.mysite.com to mysite.com/wildcard -- the way Tumblr is set up is a perfect example of what I'd like to do. Thanks again!

Answer 1

As far as how to set up the DNS subdomain wildcard, that would be a function of your DNS hosting provider. This would be different steps depending on which hosting provider you have and would be a better question for them.

Once you've set that up with the DNS host, from your web app you really are just URL rewriting, which can be done with some sort of module for the web server itself, such as isapi rewrite if you're on IIS (this would be the prefered route if possible). You could also handle rewriting at the application level as well (like using routing if on ASP.NET).

You'd rewrite the URL so http://myname.domain.com would become http://domain.com/something.aspx?name=myname or something. From there on out, you just handle it as if the myname value was in the query string as normal. Does that make sense? Hope I didn't misunderstand what you're after.

Edit:

I am not suggesting that you create a subdomain for each user, but instead create a wildcard subdomain for the domain itself, so anything.domain.com (basically *.domain.com) goes to your site. I have several domains setup with mydomain. Their instructions for setting this up is like this:

Yes, you can configure a wild card but it will only work if you set it up as an A Record. Wildcards do not work with a C Name. To use a wildcard, you use the astericks character '*'. For example, if you create and A Record using a wild card, .domain.com, anything that is entered in the place where the '' is located, will resolve to the specified IP address. So if you enter 'www', 'ftp', 'site', or anything else before the domain name, it will always resolve to the IP address

I have some that are setup in just this way, having *.domain.com go to my site. I then can read the base URL in my web app to see that ryan.domain.com is what was currently accessed, or that bill.domain.com is what was used. I can then either:

1. Use URL rewriting so that the subdomain becomes a part of the query string OR
2. Simply read the host value from the accessed URL and perform some logic based on that value.

Does that make sense? I have several sites set up in just this exact way: create the wildcard for the domain with the DNS host and then simply read the host, or base domain from the URL to decide what to display based on the subdomain (which was actually a username)

Edit 2:

There is no way to do this without a DNS entry. The "online world" needs to know that name1.domain.com, name2.domain.com,...,nameN.domain.com all go to the IP address for your server. The only way to do this is with the appropriate DNS entry. You have to add the wildcard DNS entry for your domain with your DNS host. Then it's just a matter of you reading the subdomain from the URL and taking the appropriate action in your code.

Answer 2

The best thing to do if you are running *AMP is to do what Thomas suggests and do virtual hosts in Apache. You can do this either with or without the redirect you describe.

Virtual hosts

Most likely you will want to do name-based virtual hosts, as it's easiest to set up and only requires one IP address (so will also be easy to set up and test on your local MAMP machine). IP-based virtual hosts is better in some other respects, but you have to have an IP address for each domain.

This Wikipedia page discusses the differences and links to a good basic walk-thru of how to do name-based vhosts at the bottom.

On your local machine for testing, you'll also have to set up fake DNS names in /etc/hosts for your fake test domain names. i.e. if you have Apache listening on localhost and set up vhost1.test.domain and vhost2.test.domain in your Apache configs, you'd just add these domains to the 127.0.0.1 line in /etc/hosts, after localhost:

127.0.0.1 localhost vhost1.test.domain vhost2.test.domain

Once you've done the /etc/hosts edit and added the name-based virtual host configs to your Apache configuration file(s), that's it, restart Apache and your test domains should work.

Redirect with mod_rewrite

If you want to do redirects with mod_rewrite (so that user.example.com isn't directly hosted and instead redirects to example.com/user), then you will also need to do a RewriteCond to match the subdomain and redirect it:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^subdomain\.example\.com
RewriteRule ^(.*)$ http://example.com/subdomain$1 [R]

You can put this in a .htaccess or in your main Apache config.

You will need to add a pair of rules like the last two for each subdomain you want to redirect. Or, you may be able to capture the subdomain in a RewriteCond to be able to use one wildcard rule to redirect *.example.com to example.com/ * -- but that smells really bad to me from a security standpoint.

All together, vhosts and redirect

It's better to be more explicit and set up a virtual host configuration section for each hostname you want to listen for, and put the rewrite rules for each of these hostnames inside its virtual host config. (It is always more secure and faster to put this kind of stuff inside your Apache config and not .htaccess, if you can help it -- .htaccess slows performance because Apache is constantly scouring the filesystem for .htaccess files and reparsing them, and it's less secure because these can be screwed up by users.)

All together like that, the vhost config inside your Apache configs would be:

NameVirtualHost 127.0.0.1:80

# Your "default" configuration must go first
<VirtualHost 127.0.0.1:80>
  ServerName example.com
  ServerAlias www.example.com
  DocumentRoot /www/siteroot
  # etc.
</VirtualHost>

# First subdomain you want to redirect
<VirtualHost 127.0.0.1:80>
  ServerName vhost1.example.com
  RewriteEngine On
  RewriteRule ^(.*)$ http://example.com/vhost1$1 [R]
</VirtualHost>

# Second subdomain you want to redirect
<VirtualHost 127.0.0.1:80>
  ServerName vhost2.example.com
  RewriteEngine On
  RewriteRule ^(.*)$ http://example.com/vhost2$1 [R]
</VirtualHost>