Help File Library: Apache: Virtual Hosting Behind a Cable/DSL
Router
Written By:
J. Voth
Cable and DSL are, without a doubt, the two coolest things since sliced
bread. With the advent of said technolgies, people are finally getting
the benefits of a dedicated, "always-on" connection to the internet,
making setting up web and mail servers at home much easier, less expensive
and certainly more fun than the old dial up days. If you don't have cable
or DSL, get it. If you can't, then move somewhere where you can. It is
most definitely worth it. Anyways, I decided to write this Help File because I
was having some problems getting Apache Web Server to serve web pages to
internet users behind my DSL router. I could easily set up Apache and
make it work, with just one web site on the server. The real trick is
getting two or more websites published to the internet, on an Apache Web
Server behind a single IP. In Apache-ese, serving two or more websites on
one instance of httpd (Apache), is called virtual hosting. If your
familiar with Microsoft's Internet Information Server, then you'll know
this as using host header names.
This Help File is designed to help those who have some familiarity (no expertise
required however) with IP, DNS and Apache. I'm assuming that you already
have a DNS server of some kind, whether it is on your own personal LAN, or
you're using a service provider's name servers, like World Wide DNS
(http://www.worldwidedns.net). Also, you'll need to have purchased a
unique domain name from somewhere like http://www.domainmonger.com (only
$17 a year per domain name, pretty cheap). Your DNS server does not have
to be a Linux box either, by the way. You'll need, well, a cable/DSL
router with a working connection to the internet, and have Linux, I'll be
using Red Hat 7 in my example, with Apache 1.3.12 installed. This will
not be a Help File on installation of any distro, or a Bind and DNS lesson
either, by the way. I'm not quite experienced enough to write on that
yet. I don't think we have any Help Files on Bind yet, but if you happen to
not understand DNS, then I suggest going to http://www.amazon.com and
searching for some books on the subject, because DNS can be pretty tricky
sometimes.
Okay, so you've got all the requirements mentioned above taken care of.
Now you need to know if your internet service provider, issues you a
static IP address or if it is dynamically assigned to your router's WAN
link. I went ahead and paid a little extra and got an ISP that issues
out static IP addresses for the simple fact that I wanted to host web
sites and set up my own mail server, etc., etc. I suggest you do the same
because if your router's WAN link is getting it's IP address assigned to
it dynamically, then you'll have to go and change your host records on
your DNS server every time that your IP address changes. That would
suck, trust me. So let's get down to business shall we. I'll be using
examples from my own personal LAN, so your settings and domain names will
be different. The first thing we will worry about is configuring our
router/firewall. Every cable/DSL router I've seen has built in, but
limited, firewall capabilities and web browser based configuration
utility. So the main things we will worry about here are:
1. IP addresses
2. Port filtering
Set the LAN IP address to some non routable address like 192.168.123.254.
Set your WAN IP, subnet mask, and default gateway to whatever addresses
your ISP has given you. My settings are WAN IP: 64.30.204.21, subnet
mask: 255.255.255.0, and WAN gateway: 64.30.204.254.
Ensure the DHCP server for your router is disabled, as you'll need a
static IP for your internal webserver. Our webservers IP is going to be
192.168.123.2 and its fully qualified domain name is rh.thevoths.com.
Set a filter for port 80 to route to IP 192.168.123.2.If you have a DNS
server on your internal LAN, ensure that ports 53 and 113 are filtered to
your internal DNS server. That should be it as far as configuring our
router. Not too bad yet, eh?
The next thing we'll do is configure our zone file on our DNS server.
This is the trickiest part of this whole operation in my mind. Not
actually carrying out the operation but figuring out gave me some
headaches. I'm not going to go through Bind specifically as any DNS
server will do. If your using a service provider's DNS server's, then
they will more than likely have some sort of webpage to configure your
zone files. Again, if your not sure about zone files and host records
and such, then please do some research on it as it is very useful and
important information, especially if you want to learn Linux. Some DNS
service providers will allow you to call them and tell them what records
to add to your zone files, so you could take that route if you like. You
must have a registered domain name also. As I wanted to host a web site
for a friend of mine who was hired to design a web site for a new band
called Gimp', we will be using a name that I registered, gimpmusic.net,
and my own personal domain, thevoths.com. My zone file's (called simply,
thevoths.com) records look like this (yours will not have the same
hostnames):
NS ns1.worldwidedns.net
NS ns2.worldwidedns.net
www.thevoths.com A 64.30.204.21
www.thevoths.com A 192.168.123.3
rh.thevoths.com A 192.168.123.3
The NS means nameserver record and A means host record. The convention
I've used here is this: www should point to your WAN link ( being that
that's the only address that the internet knows about), it should also
point to the webserver's nonroutable IP address (192.168.123.3), and
their needs to be an A record in their for our webserver's actual
hostname (I could have actually named our webserver www.thevoths.com and
leave out the extra A record for rh.thevoths.com, I just like to name my
servers after their OS, personal preference only), don't use
cnames(aliases) because they will conflict with Apache's httpd.conf file
when you configure the virtual hosts. If your not sure what all this is,
then just register a domain name, get a DNS service provider, and have
them help you configure your zone just like we did above. If you do have
a good grasp of DNS then your probably wondering why the heck I didn't use
a CNAME, and you'll see why in the next section about configuring Apache
to use virtual hosts. By the way gimpmusic.net will look like this:
NS ns1.worldwidedns.net
NS ns2.worldwidedns.net
www.gimpmusic.net A 64.30.204.21
www.gimpmusic.net A 192.168.123.3
Configuring Apache for virtual hosts or vhosts is fairly simple. We will
be working with version 1.3.12. Go into your http.conf ( in Red Hat 7.0
- /etc/httpd/conf/httpd.conf) and get ready to do some exciting text
editing. By this time during this process I am totally pumped up and can
barely contain myself....just kidding. Okay, the first thing we will do
is add the NameVirtualHost directive and then we will add the
directives. Make sure Bind Address (it's a setting in
httpd.conf, I don't mean an actual Bind nameserver) is set to
192.168.123.3. Simply add this code into httpd.conf similar to the
following:
NameVirtualHost 192.168.123.3
ServerName www.thevoths.com
DocumentRoot
/var/www/html/thevoths
ServerName www.gimpmusic.net
DocumentRoot /var/www/html/gimpmusic
Notice that the NameVirtualHost and the directives point to
the nonroutable IP address of the webserver which is 192.168.123.3, not
the WAN IP address on the router. You see the whole idea behind NAT
routing (which is what cable/DSL routers are) is that you have only one
IP address exposed to the outside world. So if you want to publish web
servers and what not to the internet, then in DNS you would ensure that
your webserver's hostname would resolve to your router's WAN IP address.
You would then filter the appropriate port, which in our case we used the
standard port 80 for our webserver. Also in DNS, you would ensure that on
your internal network your webserver can reslove to the nonroutable IP
address that it is actually assigned(192.168.123.3 in our case). I know
this sounds like somewhat of a complicated DNS setup and I agree with you.
The only way I could get vhosts to work, however, was doing it this exact
same way. DNS was the tricky thing to figure out for me on this one but
this setup works for great. So if you visit http://www.gimpmusic.net,
then you will be visiting a site that is powered by Apache and is sitting
behind a DSL router with a strange DNS setup. Hopefully, this will help
someone out tremendously if they are having problems getting your
webserver or mail server to publish to the internet behind a single IP
address.
