raheel at raheelhameed dot com)This section first discusses some legal matters, requisites, uses of this document and links where its latest version can be found.
This document is Copyright (c) 2003 by Raheel Abdul Hameed
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
For the full text of the license, please visit GNU Free Documentation License.
Use the information in this document at your own risk. I disavow any potential liability for the contents of this document. Use of the concepts, examples, and/or other content of this document is entirely at your own risk.
All copyrights are owned by their owners, unless specifically noted otherwise. Use of a term in this document should not be regarded as affecting the validity of any trademark or service mark.
Naming of particular products or brands should not be seen as endorsements.
You are strongly recommended to take a backup of your system before major installation and backups at regular intervals.
The latest version of this document is available at http://www.tldp.org/HOWTO/Web-Browsing-Behind-ISA-Server.html
This document assumes that you are familiar with editing files using any of your favorite text editors, as it talks about editing a configuration file. Some familiarity with ISA server configuration is also favorable, but not necessary.
This document tries to be useful in the following situations:
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ISA Server provides many important networking functions that include Firewalling, Web-cache, Policy-based Administration, Dynamic IP Filtering, VPN Support, Intrusion Detection, NAT and reporting. While being a robust solution for Windows-based clients, its a pain for Linux users because most of the Linux-based browsers do not appear to be working behind it. The term 'appear to be' is used because there are some known workouts for this.
While running Windows-based clients behind ISA Server, have you noticed that normally you could browse using only Internet Explorer, and not using other browsers like Netscape? This is because ISA server uses an authentication mechanism it calls 'Integrated Authentication.' When Internet Explorer contacts ISA server to request a page, along with every request it sends a hash that the server uses to authenticate you as a legitimate domain user [You can verify this fact by sniffing some packets while you browse, just check the request header that your browser sends to the ISA server]. This authentication method is not supported by other browsers, which is why it renders most of the browsers useless.
The following sections will tell you about two methods to enable your Linux-based browser to browse the net.
As mentioned above, due to Integrated Authentication support configured on ISA server, third party browsers do not work behind it. In this situation you can make use of another authentication scheme called 'Basic Authentication', commonly supported by most browsers and most importantly by ISA Server too. If you work in a security conscious environment this method is not recommended since during basic authentication, the username and password sent are loosely encrypted.
The point here is that to proceed with this method you will have to make sure that you have legitimate access over configuring the ISA Server. If you cannot access the server configuration console, then move on to the second method in the following section.
All you need to do is fire up 'ISA Management' and follow these steps:
In particular, we will take Netscape as an example here.
Load up a test url in your browser, it will ask you for authentication information, In place of user, type DOMAIN\USER, where your DOMAIN being the Windows domain, and USER being a legitimate domain user. In place of password, type the user's password. Click on OK to continue. For example:
User: CABLENET\Raheel Password: Mypassword Where CABLENET is my domain, Raheel is the user id and Mypassword is my password.
You should now see the page loading successfully. If you use a different browser you will need to explore and see if it supports Basic Authentication.
NTLM Authorization Proxy Server is proxy server-like software that just provides NTLM authentication in between your browser and ISA Server, and makes the server believe it's talking to Internet Explorer. It does this by adding NTLM authorization strings to the request headers. It is written in the Python language by Dmitry Rozmanov [nice work dude!]. See www.python.org. Most linux distributions come bundled with a Python interpreter.
The NTLMAPS project home page is located at http://ntlmaps.sourceforge.net/. You can directly go to the download page at http://sourceforge.net/project/showfiles.php?group_id=69259. The recent version at the time of writing this document is 0.9.8.
Once you have downloaded NTLMAPS, you can extract it into the directory of your choice:
tar xzvf apsxxx.tar.gz
cd apsxxx
where 'xxx' is the version number.
Load up server.cfg in your favorite editor. Locate the lines:
LISTEN_PORT:5865
# If you want APS to authenticate you at WWW servers using NTLM then just leave this
# value blank like PARENT_PROXY: and APS will connect to web servers directly.
# And NOTE that NTLM cannot pass through another proxy server.
PARENT_PROXY:your_parentproxy
PARENT_PROXY_PORT:8080
By default, NTLMAPS listens on port 5865. You can change it to any port number of your choice. You need to replace 'your_parentproxy' with the IP address of your ISA Server. Put ISA Server's web cache port in PARENT_PROXY_PORT.
Now, locate the lines:
# Windows Domain.
# NOTE: it is not full qualified internet domain, but windows network domain.
NT_DOMAIN:your_domain
# What user's name to use during authorization. It may differ form real current username.
USER:username_to_use
# Password. Just leave it blank here and server will request it at the start time.
PASSWORD:your_nt_password
You will need to put in your domain name in place of your_domain, user name in place of 'username_to_use' and password in place of 'your_nt_password'. Save the file after editing.
Now simply run the file main.py, for example:
./main.py
Now the NTLMAPS server is listening.
In particular, we will use Netscape as an example here.
Load up a test url in your browser and you will see the web page loads successfully. If you use a different browser then you will need to explore and see how you set it up to work with proxy.
Microsoft Knowledge Base Article - 295667
http://support.microsoft.com/?kbid=295667
NTLM Authorization Proxy Server home page http://ntlmaps.sourceforge.net/
Python Home Page www.python.org