[ 7 October 1997

[ 7 October 1997
The Linux Virtual Web mini-HOWTO is not being maintained by
the author any more. This topic will be covered in the new
version of the Linux WWW HOWTO. ]

VirtualWeb-Mini-HOWTO

Dan Pancamo, [email protected] http://www.infocom.net/~pancamo/

v1.0, 24 November 1995 Copyright 1995

This HOWTO discuss the essentials of setting up a Virtual Web Site under Linux.

Table of Contents

1.0 What is a Virtual Web Site?
2.0 What software patched do I need?
2.1 Linux versions 1.2.X requires the IPalias patch alias-patch-1.2.1-v1
2.2 Both NCSA 1.5 and Apache support Virtual hosting.
3.0 How Do I set it up?
3.1 Creating the new account
3.2 Setting up the NCSA 1.5 and Apache config files
3.3 Configuring the interface
3.4 Registering with Internic
3.5 Configuring Named
3.5.1 Example /etc/named.boot (replace x with your IP)
3.5.2 Example /etc/named.data/db.domain1.com
3.5.3 Example /etc/named.data/db.xxx.xxx.xxx
3.5.4 restart named; i.e. named.restart
3.6 Virtual Mail
3.6.1 Sendmail configuration
3.6.1.1. Create /etc/domainalias
3.6.1.2 Create the maped DB file
3.6.1.3.1. Add a Cw record for each host
3.6.1.3.2. Add the domainalias mapping
3.6.1.3.3. Add/Change Ruleset 98
3.7 Virtual FTP

4.0 Links to more Virtual Web Information

1.0 What is a Virtual Web Site?

A World Wide Web (WWW) Server is normally a single machine dedicated to
processing HTTP requests for a single WWW site. Simply put, one WWW site
per machine. Since the computing resources for processing httpd requests is
low for most WWW sites, the majority of the computing resources are left
unused. A virtual WWW site simple allows more than one WWW site to share a
single processor. Instead of having www.domain1.com and www.domain2.com
requiring two physical computing devices, www.domain1.com and
www.domain2.com can be located on a single computing device and share common
resources.

Normally small computing facilities, and small businesses do not have the
resources to maintain a dedicated web server and a dedicated Internet
connection. These cost can easily start off at $10K for setup, and
$500-2500 monthly to maintain. Small computing facilities, and small
businesses are now able to "rent" WWW space from a Virtual WWW providers.
The customer can then maintain the WWW "pages" using a local telnet and/or
FTP connection.

WWW providers such as InfoCom Networks http://www.infocom.net/
provide WWW space as low as $75 per month. A few Virtual Sites
might clear up the mystery. So the cost of setting up a WWW site is
significantly lower than that of setting up a dedicated server and
connection. The Virtual Site has a major advantage over other WWW
addressing schemes such as "www.yourprovider.com/~businessname". The
Virtual WWW server inherently contains the ability to move to a new location
or setup a dedicated WWW server without changing addresses. Changing WWW
URL's can result in a major loss of traffic to your site, and lots of
business literature updates.

With most web sites, www.domain1.com and www.domain2.com both resolve to
separate IP's. In order to accept multiple request from a single host, the
virtual host must be able to answer request for both sites. The method used
to solve this problem is called IP aliasing. IP aliasing allows a single
host to accept request for multiple IP's. The virtual Web server must have
the ability to alias IP's

IP aliasing is just one part of the virtual solution. The Domain Name System
(DNS) also must be configured to resolve both www.domain1.com and
www.domain2.com. If domain1.com and domain2.com are new domains, then both
must be registered with Internic. Currently, Internic is charging $50 a year
to maintain your domain.

Most virtual WWW sites should also provide virtual mail, or the ability to
forward all mail to the virtual domain to another user or users.

Virtual FTP or the ability to FTP using the standard host name
"ftp.domain1.com" should also be configured by the WWW provider.

2.0 What software patched do I need?

2.1 Linux versions 1.2.X requires the IPalias patch alias-patch-1.2.1-v1
and alias-net-tools.tar. I'm not sure if 1.3.X supports this patch yet.
For more information on the IPalias patch see
ftp://ftp.mindspring.com/users/rsanders/ipalias/

Using multiple dummy interfaces has been suggested in place of
the IPalias solution. While the dummy solution may work,
it does not appear to be as clean as the IPalias solution.
For more information on using Apache and the dummy solution
see Aram Mirzadeh's virtual hosting information at
http://www.qosina.com/apache/virtual.html

All that is required to add a new alias using the IPalias method is:
> /sbin/ifconfig eth0 alias www.domainX.com

Also, the IPalias solution is supported on several other platforms.

2.2 NCSA 1.5, Apache, and Spinner support Virtual hosting.
http://hoohoo.ncsa.uiuc.edu/docs/Overview.html
http://www.apache.org/
http://spinner.infovav.se/

3.0 How Do I set it up?

3.1 Create the new account
Create a regular Linux account for the virtual customer with home
directory and mail.

3.2 Setup the NCSA 1.5 or Apache config files

Virtual Host implementations are still changing. A few patches
exist to support Virtual Host Check the server's release notes for
more details. NCSA 1.5 or Apache now include the Virtual patches,
and I have been told that Spinner supports virtual hosts.

One virtual patch supports the following srm.conf syntax, however
the second NCSA 1.5 method of defining a Virtual host allows
for greater flexibility

SubDocumentRoot www.domain1.com /usr/local/etc/httpd/docs/domain1
SubDocumentRoot www.domain2.com /usr/local/etc/httpd/docs/domain2

NCSA and Apache support the following httpd.conf syntax:

ServerAdmin [email protected]
DocumentRoot /usr/local/etc/httpda/docs/domain1
ServerName www.domain1.com
ErrorLog logs/errors.domain1.com
TransferLog logs/access_log.domain1.com

3.3 Configuring the interface

Once the IPalias patches have been installed add the
following to your /etc/rc.d/rc.local on your local web server.

/sbin/ifconfig eth0 alias www.domain1.com
/sbin/ifconfig eth0 alias www.domain2.com
/sbin/ifconfig eth0 alias www.domainN.com

3.4 Registering with Internic

If you are setting up a new domain or change a current
domain, you must register the domain with Internic.
The template can be found at
ftp://rs.internic.net/templates/domain-template.txt

3.5 Configuring Named

Named will need to be configured so that your virtual domain will
be visible to the outside world. I don't claim to be an expert
on DNS. Suggestions always welcome.

3.5.1 Example /etc/named.boot (replace x with your IP)

directory /etc/named.data
primary realdomain.com db.realdomain.com
primary xxx.xxx.xxx.IN-ADDR.ARPA db.xxx.xxx.xxx
primary 0.0.127.IN-ADDR.ARPA db.local

primary domain1.com db.domain1.com
primary domain2.com db.domain2.com
cache . named.root

3.5.2 Example /etc/named.data/db.domain1.com

$ORIGIN com.
domain1 IN SOA domain1.com. hostmaster.domain1.com. (
10134 43200 3600 604800 86400 )
IN NS ns1.realdomain.com.
IN MX 10 mail.realdomain.com.
IN MX 0 domain1.com.
domain1.com. IN A xxx.xxx.xxx.xxx ;www.domain1.com IP

$ORIGIN domain1.com.
ftp IN CNAME domain1.com.
www IN CNAME domain1.com.
mail IN CNAME domain1.com.

3.5.3 Example /etc/named.data/db.xxx.xxx.xxx

You should already have a db.xxx.xxx.xxx for your current site
update it to contain the new virtual domains for reverse lookups

xx IN PTR www.domain1.com.
xx IN PTR www.domain2.com.

3.5.4 restart named; i.e. named.restart

3.6 Virtual Mail

Your virtual customers will more than likely want the ability to have
mail that is sent to their domain forwarded to another domain. A few
sendmail.cf changes will do the trick. After several months of
trying different sendmail changes, this is the 1st method that I
found that works and requires only one sendmail.cf change for each
new virtual site.

3.6.1 Sendmail configuration

Retrieve the current version of sendmail that contains makemap btree support

3.6.1.1. Create a file called /etc/domainalias with the following mappings:

*@domain1.com [email protected]
*@domain2.com [email protected]
*@domainN.com [email protected]

[email protected] [email protected]
[email protected] [email protected]

3.6.1.2 Create the maped DB file

> makemap btree /etc/domainalias.db < /etc/domainalias

3.6.1.3. /etc/sendmail.cf changes:

3.6.1.3.1. Add a Cw record for each new virtual host

Cwdomain1.com
Cwdomain2.com

3.6.1.3.2. Add the domainalias mapping only once

Kdomainalias btree /etc/domainalias.db

3.6.1.3.3. Add/Change Ruleset 98

###################################################################
### Ruleset 98 -- local part of ruleset zero (can be null) ###
###################################################################

S98

R$+ < $+ . > $1 < $2 > remove trailing dots
R$+ < $+ > $: < > $(domainalias $1$2 $) match user@address
R< > $+ @ $* $: < $1 > $(domainalias * @ $2 $) match *@address
R< $+ > * $* $: < > $1 $2 replace * with userid
R < $+ > $+ $: < > $2 bugfix
R< > $* $: $>3 $1 and rewrite using S3

3.5.1.4 Sendmail Testing
Test the sendmail configuration to verify the new
sendmail.cf changes
> sendmail -v -bv [email protected]
The final destination should be displayed.

3.7 Virtual FTP

Currently, I have not been able to get Virtual FTP to work.
A few patches exist, and I'm sure a working patch exist.
We just create a working directory /home/ftp/business/domain1,
but a true Virtual FTP would be nice.

If anyone would like to contribute a solution, I would be more
than happy to add it here.

Arnt Gulbrandsen has rewritten ftpd and has included support for
independent FTP services The Troll Tech FTP Daemon

4.0 Links to more Virtual Web information

http://hoohoo.ncsa.uiuc.edu/docs/Overview.html
http://www.apache.org/
http://www.qosina.com/apache/virtual.html
http://spinner.infovav.se/
ftp://ftp.mindspring.com/users/rsanders/ipalias/
http://www.thesphere.com/~dlp/TwoServers/
http://hoohoo.ncsa.uiuc.edu/docs/setup/httpd/VirtualHost.html
ftp://ftp.dhp.com:/pub/linux/virtual-hosting