Instant file sharing with IPv6 and WebDAV

Kenichi Takahashi
Assistant Manager, Network Service Division, NTT Software


If you work at your office and your home (and other places), you want a digital storage where you can put all your files to work on. Or you may have experienced difficulty exchanging files of several tens of megabytes with your friends or your customers over the Internet. These are when you wish you had a file sharing server running at home.

But then you encounter two obstacles: you need a global IP address to set up an Internet-accessible server, while routers and firewalls usually do not allow file sharing protocols to go through, making things complicated.

Enter WebDAV. It uses HTTP, so firewall does not need to be reconfigured in most cases. Global address issue can be solved by running WebDAV server on IPv6. I will show you how you can easily share files using WebDAV and IPv6.


What is WebDAV?

Let me briefly explain what WebDAV is. WebDAV is short for “Web-based Distributed Authoring and Versioning”. It enhances HTTP for publishing contents as well as viewing them. Use of WebDAV has the following advantages.

• Access to your files over the Internet
  It is a Web-based service using only port 80 (port 433 when applying SSL/TLS). Therefore, you can immediately start using this through firewalls as long as they have port 80 opened.
  
• Web-like security handling
  You can apply most security mechanisms for Web. WebDAV is easier in security management than FTP or SMB over the Internet.
  
• Ving or Independency from OS or language
  WebDAV specifications are independent from OS or hardware, and implementations are available on multiple platforms. WebDAV-spec\ific enhancements of HTTP are very versatile, using XML for data exchanges, for example.
  
• Simple and effective
  WebDAV includes methods for moving and copying files on the server. Therefore, no download and upload is necessary for these functions.

WebDAV, has many advantages over other file transfer/sharing protocols such as FTP or SMB. WebDAV has an added functionality of versioning, keeping consistency when multiple users modify the same files, which is clearly suitable for file sharing.


Building WebDAV server with Apache 2.0 for Win32

Then let’s set up a WevDAV server. Microsoft has IIS (Internet Information Server) on Windows NT/2000/XP Professional, which includes WebDAV implementation. But IIS is not IPv6-enabled at present (IPv6 will be supported on IIS 6.0, to be available on Windows Server 2003, the next server version of Windows). In this article, I will use Apache 2.0 for Win32 with built-in IPv6 support, to run a WebDAV server on Windows XP.

1. Apache 2.0 download and install.

Apache 2.0 for Win32 is IPv6-enabled, but Win32 platform by apache.org is not. You can get the latest source code and compile it, but this time, we’ll download binary rebuilt with IPv6 enabled for install.

Apache 2.0.44 for Win32 is available at:
http://nagoya.apache.org/mirror/httpd/binaries/win32/

Apache 2.0.44 for Win32 (IPv6 enabled) binary is available at:
http://win6.jp/Apache2/index-j.html

Download apache_2.0.44-win32-x86-no_ssl.msi and httpd_2.0.44-win32-ipv6.zip from the above directories. Installation of Apache is no different from other applications. But you need to disable IIS to avoid conflict on port 80.

After installation, Apache 2.0 will be automatically started as a service. Stop the service for introducing IPv6 binaries. The following files need to be replaced:

• bin/*.exe
  
• include/*.h
  
• lib/*
  
• modules/*.so

Restart Apache 2.0 and confirm localhost with your browser.


Figure 1

*During Apache 2.0 restart, you may see a {×úSVCR70.DLL is not foundzíÓmessage(Figure 2). This is because IPv6-enabled binary asks for Visual Studio.NET runtime. If this message appears, you can install Microsoft .NET Framework, including MSVCR70.DLL, through Windows Update. If you still encounter this message, you can search for msvcr70.dll and put this file in C:\windows\system32.


Figure2

2. Create share folder

Default configuration of Apache 2.0 does not have WebDAV enabled. Let’s introduce WebDAV with the following procedure.

In Apache 2.0, default document root directory is htdocs folder under install folder(default is c:\Program Files\Apache Group\Apache2). Create dav folder under htdocs so that this new folder can be shared with WebDAV

3. Open port 80 and enable mod_dav

Apache 2.0 installation includes mod_dav module, which provides WebDAV, but this module is not enabled by default. You need to modify httpd.conf in conf folder under Apache install folder (C:\Program Files\Apache Group\Apache2) as follows:

# Listen 80 # Comment out # Add the following 2 lines Listen 0.0.0.0:80 Listen [::]:80 LoadModule foo_module modules/mod_dav.so # Remove comment LoadModule foo_module modules/mod_dav_fs.so # Remove comment # Add the following lines <IfModule mod_dav.c> Alias /share "C:/Program Files/Apache Group/Apache2/htdocs/share" <Location /share> DAV On </Location> </IfModule>

Above configuration enables WebDAV. Restart Apache 2.0 to enable the new configuration. If error is indicated during restart, go back to the configuration file to correct errors.


Figure 3

Now, WebDAV server is up and running on Windows platform. Let’s access WebDAV folder from client.


Connecting to WebDAV server from Windows XP

Windows XP has WebDAV client called Network Place. You can easily access this as Web Folder with Windows Explorer. If you have IPv6 enabled on your client computer, you can easily start using WebDAV on IPv6 with a little more configuration (for installation of IPv6 protocol, read “Experiencing IPv6 with Windows XP” article on this site).

You need to modify hosts file to resolve the server IPv6 address with Network Place. Add the following lines to C:\WINDOWS\system32\drivers\etc\hosts.

# IPv6 WebDAVserver 2001:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx webdavserver

Then open {×úy NetworkzãÂn your desktop, and click on {زdd Network Placezã¡o start Add Network Place Wizard (Figure 4).


Figure 4

Add URL for Service Provider, after selecting {ØÆhoosing Other Network PlaceszãÚn the Wizard (Figure 5).


Figure5

If the WebDAV server is recognized, enter the name of Network Place to finish the configuration (Figure 6).


Figure6

You will see your WebDAV server directory by clicking on the Network Place icon.


Figure7


IPv6 enhances possibilities of file sharing

If all home appliances will be networked in the future, current IPv4 will face address shortage, encouraging the move to IPv6. Sooner or later, you will begin to retrieve documents, digital camera photo images, and movie files for viewing outside. By building WebDAV on IPv6, you can experience the future.

This article has not covered security and other details of WebDAV, but please try out these features. Youçøl find new opportunities with IPv6.