+++ /dev/null
-<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 12. Integrating Additional Services</title><link rel="stylesheet" href="../samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.75.2"><link rel="home" href="index.html" title="Samba-3 by Example"><link rel="up" href="RefSection.html" title="Part III. Reference Section"><link rel="prev" href="kerberos.html" title="Chapter 11. Active Directory, Kerberos, and Security"><link rel="next" href="HA.html" title="Chapter 13. Performance, Reliability, and Availability"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 12. Integrating Additional Services</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="kerberos.html">Prev</a> </td><th width="60%" align="center">Part III. Reference Section</th><td width="20%" align="right"> <a accesskey="n" href="HA.html">Next</a></td></tr></table><hr></div><div class="chapter" title="Chapter 12. Integrating Additional Services"><div class="titlepage"><div><div><h2 class="title"><a name="DomApps"></a>Chapter 12. Integrating Additional Services</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="DomApps.html#id382225">Introduction</a></span></dt><dd><dl><dt><span class="sect2"><a href="DomApps.html#id382248">Assignment Tasks</a></span></dt></dl></dd><dt><span class="sect1"><a href="DomApps.html#id382338">Dissection and Discussion</a></span></dt><dd><dl><dt><span class="sect2"><a href="DomApps.html#id382367">Technical Issues</a></span></dt><dt><span class="sect2"><a href="DomApps.html#id382513">Political Issues</a></span></dt></dl></dd><dt><span class="sect1"><a href="DomApps.html#id382530">Implementation</a></span></dt><dd><dl><dt><span class="sect2"><a href="DomApps.html#ch10-one">Removal of Pre-Existing Conflicting RPMs</a></span></dt><dt><span class="sect2"><a href="DomApps.html#id384281">Key Points Learned</a></span></dt></dl></dd><dt><span class="sect1"><a href="DomApps.html#id384336">Questions and Answers</a></span></dt></dl></div><p>
- <a class="indexterm" name="id382181"></a>
- <a class="indexterm" name="id382187"></a>
- <a class="indexterm" name="id382194"></a>
- <a class="indexterm" name="id382201"></a>
- <a class="indexterm" name="id382208"></a>
- You've come a long way now. You have pretty much mastered Samba-3 for
- most uses it can be put to. Up until now, you have cast Samba-3 in the leading
- role, and where authentication was required, you have used one or another of
- Samba's many authentication backends (from flat text files with smbpasswd
- to LDAP directory integration with ldapsam). Now you can design a
- solution for a new Abmas business. This business is running Windows Server
- 2003 and Active Directory, and these are to stay. It's time to master
- implementing Samba and Samba-supported services in a domain controlled by
- the latest Windows authentication technologies. Let's get started this is
- leading edge.
- </p><div class="sect1" title="Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id382225"></a>Introduction</h2></div></div></div><p>
- Abmas has continued its miraculous growth; indeed, nothing seems to be able
- to stop its diversification into multiple (and seemingly unrelated) fields.
- Its latest acquisition is Abmas Snack Foods, a big player in the snack-food
- business.
- </p><p>
- With this acquisition comes new challenges for you and your team. Abmas Snack
- Foods is a well-developed business with a huge and heterogeneous network. It
- already has Windows, NetWare, and Proprietary UNIX, but as yet no Samba or Linux.
- The network is mature and well-established, and there is no question of its chosen
- user authentication scheme being changed for now. You need to take a wise new
- approach.
- </p><p>
- You have decided to set the ball rolling by introducing Samba-3 into the network
- gradually, taking over key services and easing the way to a full migration and,
- therefore, integration into Abmas's existing business later.
- </p><div class="sect2" title="Assignment Tasks"><div class="titlepage"><div><div><h3 class="title"><a name="id382248"></a>Assignment Tasks</h3></div></div></div><p>
- <a class="indexterm" name="id382256"></a>
- <a class="indexterm" name="id382264"></a>
- You've promised the skeptical Abmas Snack Foods management team
- that you can show them how Samba can ease itself and other Open Source
- technologies into their existing infrastructure and deliver sound business
- advantages. Cost cutting is high on their agenda (a major promise of the
- acquisition). You have chosen Web proxying and caching as your proving ground.
- </p><p>
- <a class="indexterm" name="id382279"></a>
- <a class="indexterm" name="id382286"></a>
- Abmas Snack Foods has several thousand users housed at its head office
- and multiple regional offices, plants, and warehouses. A high proportion of
- the business's work is done online, so Internet access for most of these
- users is essential. All Internet access, including for all regional offices,
- is funneled through the head office and is the job of the (now your) networking
- team. The bandwidth requirements were horrific (comparable to a small ISP), and
- the team soon discovered proxying and caching. In fact, they became one of
- the earliest commercial users of Microsoft ISA.
- </p><p>
- <a class="indexterm" name="id382301"></a>
- <a class="indexterm" name="id382308"></a>
- <a class="indexterm" name="id382315"></a>
- The team is not happy with ISA. Because it never lived up to its marketing promises,
- it underperformed and had reliability problems. You have pounced on the opportunity
- to show what Open Source can do. The one thing they do like, however, is ISA's
- integration with Active Directory. They like that their users, once logged on,
- are automatically authenticated against the proxy. If your alternative to ISA
- can operate completely seamlessly in their Active Directory domain, it will be
- approved.
- </p><p>
- This is a hands-on exercise. You build software applications so
- that you obtain the functionality Abmas needs.
- </p></div></div><div class="sect1" title="Dissection and Discussion"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id382338"></a>Dissection and Discussion</h2></div></div></div><p>
- The key requirements in this business example are straightforward. You are not required
- to do anything new, just to replicate an existing system, not lose any existing features,
- and improve performance. The key points are:
- </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
- Internet access for most employees
- </p></li><li class="listitem"><p>
- Distributed system to accommodate load and geographical distribution of users
- </p></li><li class="listitem"><p>
- Seamless and transparent interoperability with the existing Active Directory domain
- </p></li></ul></div><div class="sect2" title="Technical Issues"><div class="titlepage"><div><div><h3 class="title"><a name="id382367"></a>Technical Issues</h3></div></div></div><p>
- <a class="indexterm" name="id382375"></a>
- <a class="indexterm" name="id382381"></a>
- <a class="indexterm" name="id382388"></a>
- <a class="indexterm" name="id382395"></a>
- <a class="indexterm" name="id382402"></a>
- <a class="indexterm" name="id382409"></a>
- <a class="indexterm" name="id382415"></a>
- <a class="indexterm" name="id382422"></a>
- <a class="indexterm" name="id382429"></a>
- <a class="indexterm" name="id382436"></a>
- <a class="indexterm" name="id382443"></a>
- <a class="indexterm" name="id382450"></a>
- <a class="indexterm" name="id382459"></a><a class="indexterm" name="id382464"></a>
- Functionally, the user's Internet Explorer requests a browsing session with the
- Squid proxy, for which it offers its AD authentication token. Squid hands off
- the authentication request to the Samba-3 authentication helper application
- called <code class="literal">ntlm_auth</code>. This helper is a hook into winbind, the
- Samba-3 NTLM authentication daemon. Winbind enables UNIX services to authenticate
- against Microsoft Windows domains, including Active Directory domains. As Active
- Directory authentication is a modified Kerberos authentication, winbind is assisted
- in this by local Kerberos 5 libraries configured to check passwords with the Active
- Directory server. Once the token has been checked, a browsing session is established.
- This process is entirely transparent and seamless to the user.
- </p><p>
- Enabling this consists of:
- </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
- Preparing the necessary environment using preconfigured packages
- </p></li><li class="listitem"><p>
- Setting up raw Kerberos authentication against the Active Directory domain
- </p></li><li class="listitem"><p>
- Configuring, compiling, and then installing the supporting Samba-3 components
- </p></li><li class="listitem"><p>
- Tying it all together
- </p></li></ul></div></div><div class="sect2" title="Political Issues"><div class="titlepage"><div><div><h3 class="title"><a name="id382513"></a>Political Issues</h3></div></div></div><p>
- You are a stranger in a strange land, and all eyes are upon you. Some would even like to see
- you fail. For you to gain the trust of your newly acquired IT people, it is essential that your
- solution does everything the old one did, but does it better in every way. Only then
- will the entrenched positions consider taking up your new way of doing things on a
- wider scale.
- </p></div></div><div class="sect1" title="Implementation"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id382530"></a>Implementation</h2></div></div></div><p>
- <a class="indexterm" name="id382538"></a>
- First, your system needs to be prepared and in a known good state to proceed. This consists
- of making sure that everything the system depends on is present and that everything that could
- interfere or conflict with the system is removed. You will be configuring the Squid and Samba-3
- packages and updating them if necessary. If conflicting packages of these programs are installed,
- they must be removed.
- </p><p>
- <a class="indexterm" name="id382552"></a>
- The following packages should be available on your Red Hat Linux system:
- </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
- <a class="indexterm" name="id382566"></a>
- <a class="indexterm" name="id382572"></a>
- krb5-libs
- </p></li><li class="listitem"><p>
- krb5-devel
- </p></li><li class="listitem"><p>
- krb5-workstation
- </p></li><li class="listitem"><p>
- krb5-server
- </p></li><li class="listitem"><p>
- pam_krb5
- </p></li></ul></div><p>
- <a class="indexterm" name="id382602"></a>
- In the case of SUSE Linux, these packages are called:
- </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
- heimdal-lib
- </p></li><li class="listitem"><p>
- heimdal-devel
- </p></li><li class="listitem"><p>
- <a class="indexterm" name="id382625"></a>
- heimdal
- </p></li><li class="listitem"><p>
- pam_krb5
- </p></li></ul></div><p>
- If the required packages are not present on your system, you must install
- them from the vendor's installation media. Follow the administrative guide
- for your Linux system to ensure that the packages are correctly updated.
- </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
- <a class="indexterm" name="id382648"></a>
- <a class="indexterm" name="id382655"></a>
- <a class="indexterm" name="id382662"></a>
- If the requirement is for interoperation with MS Windows Server 2003, it
- will be necessary to ensure that you are using MIT Kerberos version 1.3.1
- or later. Red Hat Linux 9 ships with MIT Kerberos 1.2.7 and thus requires
- updating.
- </p><p>
- <a class="indexterm" name="id382673"></a>
- <a class="indexterm" name="id382680"></a>
- Heimdal 0.6 or later is required in the case of SUSE Linux. SUSE Enterprise
- Linux Server 8 ships with Heimdal 0.4. SUSE 9 ships with the necessary version.
- </p></div><div class="sect2" title="Removal of Pre-Existing Conflicting RPMs"><div class="titlepage"><div><div><h3 class="title"><a name="ch10-one"></a>Removal of Pre-Existing Conflicting RPMs</h3></div></div></div><p>
- <a class="indexterm" name="id382701"></a>
- If Samba and/or Squid RPMs are installed, they should be updated. You can
- build both from source.
- </p><p>
- <a class="indexterm" name="id382712"></a>
- <a class="indexterm" name="id382719"></a>
- <a class="indexterm" name="id382725"></a>
- Locating the packages to be un-installed can be achieved by running:
-</p><pre class="screen">
-<code class="prompt">root# </code> rpm -qa | grep -i samba
-<code class="prompt">root# </code> rpm -qa | grep -i squid
-</pre><p>
- The identified packages may be removed using:
-</p><pre class="screen">
-<code class="prompt">root# </code> rpm -e samba-common
-</pre><p>
- </p><div class="sect2" title="Kerberos Configuration"><div class="titlepage"><div><div><h3 class="title"><a name="id382764"></a>Kerberos Configuration</h3></div></div></div><p>
- <a class="indexterm" name="id382771"></a>
- <a class="indexterm" name="id382778"></a>
- <a class="indexterm" name="id382787"></a>
- <a class="indexterm" name="id382794"></a>
- The systems Kerberos installation must be configured to communicate with
- your primary Active Directory server (ADS KDC).
- </p><p>
- Strictly speaking, MIT Kerberos version 1.3.4 currently gives the best results,
- although the current default Red Hat MIT version 1.2.7 gives acceptable results
- unless you are using Windows 2003 servers.
- </p><p>
- <a class="indexterm" name="id382810"></a>
- <a class="indexterm" name="id382817"></a>
- <a class="indexterm" name="id382824"></a>
- <a class="indexterm" name="id382830"></a>
- <a class="indexterm" name="id382837"></a>
- <a class="indexterm" name="id382846"></a>
- <a class="indexterm" name="id382853"></a>
- Officially, neither MIT (1.3.4) nor Heimdal (0.63) Kerberos needs an <code class="filename">/etc/krb5.conf</code>
- file in order to work correctly. All ADS domains automatically create SRV records in the
- DNS zone <code class="constant">Kerberos.REALM.NAME</code> for each KDC in the realm. Since both
- MIT and Heimdal, KRB5 libraries default to checking for these records, so they
- automatically find the KDCs. In addition, <code class="filename">krb5.conf</code> allows
- specifying only a single KDC, even if there is more than one. Using the DNS lookup
- allows the KRB5 libraries to use whichever KDCs are available.
- </p><div class="procedure" title="Procedure 12.1. Kerberos Configuration Steps"><a name="id382882"></a><p class="title"><b>Procedure 12.1. Kerberos Configuration Steps</b></p><ol class="procedure" type="1"><li class="step" title="Step 1"><p>
- <a class="indexterm" name="id382893"></a>
- If you find the need to manually configure the <code class="filename">krb5.conf</code>, you should edit it
- to have the contents shown in <a class="link" href="DomApps.html#ch10-krb5conf" title="Example 12.1. Kerberos Configuration File: /etc/krb5.conf">“Kerberos Configuration File: /etc/krb5.conf”</a>. The final fully qualified path for this file
- should be <code class="filename">/etc/krb5.conf</code>.
- </p></li><li class="step" title="Step 2"><p>
- <a class="indexterm" name="id382926"></a>
- <a class="indexterm" name="id382933"></a>
- <a class="indexterm" name="id382940"></a>
- <a class="indexterm" name="id382947"></a>
- <a class="indexterm" name="id382953"></a>
- <a class="indexterm" name="id382960"></a>
- <a class="indexterm" name="id382967"></a>
- <a class="indexterm" name="id382974"></a>
- <a class="indexterm" name="id382981"></a>
- <a class="indexterm" name="id382990"></a>
- <a class="indexterm" name="id382996"></a>
- <a class="indexterm" name="id383003"></a>
- <a class="indexterm" name="id383010"></a>
- The following gotchas often catch people out. Kerberos is case sensitive. Your realm must
- be in UPPERCASE, or you will get an error: <span class="quote">“<span class="quote">Cannot find KDC for requested realm while getting
- initial credentials</span>”</span>. Kerberos is picky about time synchronization. The time
- according to your participating servers must be within 5 minutes or you get an error:
- <span class="quote">“<span class="quote">kinit(v5): Clock skew too great while getting initial credentials</span>”</span>.
- Clock skew limits are, in fact, configurable in the Kerberos protocols (the default is
- 5 minutes). A better solution is to implement NTP throughout your server network.
- Kerberos needs to be able to do a reverse DNS lookup on the IP address of your KDC.
- Also, the name that this reverse lookup maps to must either be the NetBIOS name of
- the KDC (i.e., the hostname with no domain attached) or the
- NetBIOS name followed by the realm. If all else fails, you can add a
- <code class="filename">/etc/hosts</code> entry mapping the IP address of your KDC to its
- NetBIOS name. If Kerberos cannot do this reverse lookup, you will get a local error
- when you try to join the realm.
- </p></li><li class="step" title="Step 3"><p>
- <a class="indexterm" name="id383045"></a>
- You are now ready to test your installation by issuing the command:
-</p><pre class="screen">
-<code class="prompt">root# </code> kinit [USERNAME@REALM]
-</pre><p>
- You are asked for your password, which you should enter. The following
- is a typical console sequence:
-</p><pre class="screen">
-<code class="prompt">root# </code> kinit ADMINISTRATOR@LONDON.ABMAS.BIZ
-Password for ADMINISTRATOR@LONDON.ABMAS.BIZ:
-</pre><p>
- Make sure that your password is accepted by the Active Directory KDC.
- </p></li></ol></div><div class="example"><a name="ch10-krb5conf"></a><p class="title"><b>Example 12.1. Kerberos Configuration File: <code class="filename">/etc/krb5.conf</code></b></p><div class="example-contents"><pre class="screen">
-[libdefaults]
- default_realm = LONDON.ABMAS.BIZ
-
-[realms]
- LONDON.ABMAS.BIZ = {
- kdc = w2k3s.london.abmas.biz
- }
-</pre></div></div><br class="example-break"><p><a class="indexterm" name="id383105"></a>
- The command
-</p><pre class="screen">
-<code class="prompt">root# </code> klist -e
-</pre><p>
- shows the Kerberos tickets cached by the system.
- </p><div class="sect3" title="Samba Configuration"><div class="titlepage"><div><div><h4 class="title"><a name="id383127"></a>Samba Configuration</h4></div></div></div><p>
- <a class="indexterm" name="id383135"></a>
- Samba must be configured to correctly use Active Directory. Samba-3 must be used, since it
- has the necessary components to interface with Active Directory.
- </p><div class="procedure" title="Procedure 12.2. Securing Samba-3 With ADS Support Steps"><a name="id383144"></a><p class="title"><b>Procedure 12.2. Securing Samba-3 With ADS Support Steps</b></p><ol class="procedure" type="1"><li class="step" title="Step 1"><p>
- <a class="indexterm" name="id383156"></a>
- <a class="indexterm" name="id383162"></a>
- <a class="indexterm" name="id383169"></a>
- <a class="indexterm" name="id383176"></a>
- <a class="indexterm" name="id383183"></a>
- Download the latest stable Samba-3 for Red Hat Linux from the official Samba Team
- <a class="ulink" href="http://ftp.samba.org" target="_top">FTP site.</a> The official Samba Team
- RPMs for Red Hat Fedora Linux contain the <code class="literal">ntlm_auth</code> tool
- needed, and are linked against MIT KRB5 version 1.3.1 and therefore are ready for use.
- </p><p>
- <a class="indexterm" name="id383207"></a>
- <a class="indexterm" name="id383213"></a>
- The necessary, validated RPM packages for SUSE Linux may be obtained from
- the <a class="ulink" href="ftp://ftp.sernet.de/pub/samba" target="_top">SerNet</a> FTP site that
- is located in Germany. All SerNet RPMs are validated, have the necessary
- <code class="literal">ntlm_auth</code> tool, and are statically linked
- against suitably patched Heimdal 0.6 libraries.
- </p></li><li class="step" title="Step 2"><p>
- Using your favorite editor, change the <code class="filename">/etc/samba/smb.conf</code>
- file so it has contents similar to the example shown in <a class="link" href="DomApps.html#ch10-smbconf" title="Example 12.2. Samba Configuration File: /etc/samba/smb.conf">“Samba Configuration File: /etc/samba/smb.conf”</a>.
- </p></li><li class="step" title="Step 3"><p>
- <a class="indexterm" name="id383261"></a>
- <a class="indexterm" name="id383268"></a>
- <a class="indexterm" name="id383274"></a>i
- <a class="indexterm" name="id383286"></a>
- <a class="indexterm" name="id383293"></a>
- Next you need to create a computer account in the Active Directory.
- This sets up the trust relationship needed for other clients to
- authenticate to the Samba server with an Active Directory Kerberos ticket.
- This is done with the <span class="quote">“<span class="quote">net ads join -U [Administrator%Password]</span>”</span>
- command, as follows:
-</p><pre class="screen">
-<code class="prompt">root# </code> net ads join -U administrator%vulcon
-</pre><p>
- </p></li><li class="step" title="Step 4"><p>
- <a class="indexterm" name="id383324"></a>
- <a class="indexterm" name="id383331"></a>
- <a class="indexterm" name="id383337"></a>
- <a class="indexterm" name="id383344"></a>
- <a class="indexterm" name="id383351"></a>
- Your new Samba binaries must be started in the standard manner as is applicable
- to the platform you are running on. Alternatively, start your Active Directory-enabled Samba with the following commands:
-</p><pre class="screen">
-<code class="prompt">root# </code> smbd -D
-<code class="prompt">root# </code> nmbd -D
-<code class="prompt">root# </code> winbindd -D
-</pre><p>
- </p></li><li class="step" title="Step 5"><p>
- <a class="indexterm" name="id383390"></a>
- <a class="indexterm" name="id383396"></a>
- <a class="indexterm" name="id383406"></a>
- <a class="indexterm" name="id383412"></a>
- <a class="indexterm" name="id383419"></a>
- We now need to test that Samba is communicating with the Active
- Directory domain; most specifically, we want to see whether winbind
- is enumerating users and groups. Issue the following commands:
-</p><pre class="screen">
-<code class="prompt">root# </code> wbinfo -t
-checking the trust secret via RPC calls succeeded
-</pre><p>
- This tests whether we are authenticating against Active Directory:
-</p><pre class="screen">
-<code class="prompt">root# </code> wbinfo -u
-LONDON+Administrator
-LONDON+Guest
-LONDON+SUPPORT_388945a0
-LONDON+krbtgt
-LONDON+jht
-LONDON+xjht
-</pre><p>
- This enumerates all the users in your Active Directory tree:
-</p><pre class="screen">
-<code class="prompt">root# </code> wbinfo -g
-LONDON+Domain Computers
-LONDON+Domain Controllers
-LONDON+Schema Admins
-LONDON+Enterprise Admins
-LONDON+Domain Admins
-LONDON+Domain Users
-LONDON+Domain Guests
-LONDON+Group Policy Creator Owners
-LONDON+DnsUpdateProxy
-</pre><p>
- This enumerates all the groups in your Active Directory tree.
- </p></li><li class="step" title="Step 6"><p>
- <a class="indexterm" name="id383476"></a>
- <a class="indexterm" name="id383483"></a>
- Squid uses the <code class="literal">ntlm_auth</code> helper build with Samba-3.
- You may test <code class="literal">ntlm_auth</code> with the command:
-</p><pre class="screen">
-<code class="prompt">root# </code> /usr/bin/ntlm_auth --username=jht
-password: XXXXXXXX
-</pre><p>
- You are asked for your password, which you should enter. You are rewarded with:
-</p><pre class="screen">
-<code class="prompt">root# </code> NT_STATUS_OK: Success (0x0)
-</pre><p>
- </p></li><li class="step" title="Step 7"><p>
- <a class="indexterm" name="id383533"></a>
- <a class="indexterm" name="id383540"></a>
- <a class="indexterm" name="id383547"></a>
- <a class="indexterm" name="id383553"></a>
- <a class="indexterm" name="id383560"></a>
- <a class="indexterm" name="id383567"></a>
- <a class="indexterm" name="id383574"></a>
- <a class="indexterm" name="id383581"></a>
- The <code class="literal">ntlm_auth</code> helper, when run from a command line as the user
- <span class="quote">“<span class="quote">root</span>”</span>, authenticates against your Active Directory domain (with
- the aid of winbind). It manages this by reading from the winbind privileged pipe.
- Squid is running with the permissions of user <span class="quote">“<span class="quote">squid</span>”</span> and group
- <span class="quote">“<span class="quote">squid</span>”</span> and is not able to do this unless we make a vital change.
- Squid cannot read from the winbind privilege pipe unless you change the
- permissions of its directory. This is the single biggest cause of failure in the
- whole process. Remember to issue the following command (for Red Hat Linux):
-</p><pre class="screen">
-<code class="prompt">root# </code> chgrp squid /var/cache/samba/winbindd_privileged
-<code class="prompt">root# </code> chmod 750 /var/cache/samba/winbindd_privileged
-</pre><p>
- For SUSE Linux 9, execute the following:
-</p><pre class="screen">
-<code class="prompt">root# </code> chgrp squid /var/lib/samba/winbindd_privileged
-<code class="prompt">root# </code> chmod 750 /var/lib/samba/winbindd_privileged
-</pre><p>
- </p></li></ol></div></div><div class="sect3" title="NSS Configuration"><div class="titlepage"><div><div><h4 class="title"><a name="id383649"></a>NSS Configuration</h4></div></div></div><p>
- <a class="indexterm" name="id383656"></a>
- <a class="indexterm" name="id383663"></a>
- <a class="indexterm" name="id383670"></a>
- For Squid to benefit from Samba-3, NSS must be updated to allow winbind as a valid route to user authentication.
- </p><p>
- Edit your <code class="filename">/etc/nsswitch.conf</code> file so it has the parameters shown
- in <a class="link" href="DomApps.html#ch10-etcnsscfg" title="Example 12.3. NSS Configuration File Extract File: /etc/nsswitch.conf">“NSS Configuration File Extract File: /etc/nsswitch.conf”</a>.
- </p><div class="example"><a name="ch10-smbconf"></a><p class="title"><b>Example 12.2. Samba Configuration File: <code class="filename">/etc/samba/smb.conf</code></b></p><div class="example-contents"><table border="0" summary="Simple list" class="simplelist"><tr><td> </td></tr><tr><td><em class="parameter"><code>[global]</code></em></td></tr><tr><td><a class="indexterm" name="id383726"></a><em class="parameter"><code>workgroup = LONDON</code></em></td></tr><tr><td><a class="indexterm" name="id383737"></a><em class="parameter"><code>netbios name = W2K3S</code></em></td></tr><tr><td><a class="indexterm" name="id383749"></a><em class="parameter"><code>realm = LONDON.ABMAS.BIZ</code></em></td></tr><tr><td><a class="indexterm" name="id383760"></a><em class="parameter"><code>security = ads</code></em></td></tr><tr><td><a class="indexterm" name="id383772"></a><em class="parameter"><code>encrypt passwords = yes</code></em></td></tr><tr><td><a class="indexterm" name="id383783"></a><em class="parameter"><code>password server = w2k3s.london.abmas.biz</code></em></td></tr><tr><td># separate domain and username with '/', like DOMAIN/username</td></tr><tr><td><a class="indexterm" name="id383799"></a><em class="parameter"><code>winbind separator = /</code></em></td></tr><tr><td># use UIDs from 10000 to 20000 for domain users</td></tr><tr><td><a class="indexterm" name="id383814"></a><em class="parameter"><code>idmap uid = 10000-20000</code></em></td></tr><tr><td># use GIDs from 10000 to 20000 for domain groups</td></tr><tr><td><a class="indexterm" name="id383829"></a><em class="parameter"><code>idmap gid = 10000-20000</code></em></td></tr><tr><td># allow enumeration of winbind users and groups</td></tr><tr><td><a class="indexterm" name="id383844"></a><em class="parameter"><code>winbind enum users = yes</code></em></td></tr><tr><td><a class="indexterm" name="id383856"></a><em class="parameter"><code>winbind enum groups = yes</code></em></td></tr><tr><td><a class="indexterm" name="id383868"></a><em class="parameter"><code>winbind user default domain = yes</code></em></td></tr></table></div></div><br class="example-break"><div class="example"><a name="ch10-etcnsscfg"></a><p class="title"><b>Example 12.3. NSS Configuration File Extract File: <code class="filename">/etc/nsswitch.conf</code></b></p><div class="example-contents"><pre class="screen">
-passwd: files winbind
-shadow: files
-group: files winbind
-</pre></div></div><br class="example-break"></div><div class="sect3" title="Squid Configuration"><div class="titlepage"><div><div><h4 class="title"><a name="id383905"></a>Squid Configuration</h4></div></div></div><p>
- <a class="indexterm" name="id383913"></a>
- <a class="indexterm" name="id383920"></a>
- Squid must be configured correctly to interact with the Samba-3
- components that handle Active Directory authentication.
- </p></div></div><div class="sect2" title="Configuration"><div class="titlepage"><div><div><h3 class="title"><a name="id383934"></a>Configuration</h3></div></div></div></div><div class="procedure" title="Procedure 12.3. Squid Configuration Steps"><a name="id383939"></a><p class="title"><b>Procedure 12.3. Squid Configuration Steps</b></p><ol class="procedure" type="1"><li class="step" title="Step 1"><p>
- <a class="indexterm" name="id383950"></a>
- <a class="indexterm" name="id383957"></a>
- <a class="indexterm" name="id383965"></a>
- If your Linux distribution is SUSE Linux 9, the version of Squid
- supplied is already enabled to use the winbind helper agent. You
- can therefore omit the steps that would build the Squid binary
- programs.
- </p></li><li class="step" title="Step 2"><p>
- <a class="indexterm" name="id383980"></a>
- <a class="indexterm" name="id383987"></a>
- <a class="indexterm" name="id383994"></a>
- <a class="indexterm" name="id384001"></a>
- <a class="indexterm" name="id384007"></a>
- Squid, by default, runs as the user <code class="constant">nobody</code>. You need to
- add a system user <code class="constant">squid</code> and a system group
- <code class="constant">squid</code> if they are not set up already (if the default
- Red Hat squid rpms were installed, they will be). Set up a
- <code class="constant">squid</code> user in <code class="filename">/etc/passwd</code>
- and a <code class="constant">squid</code> group in <code class="filename">/etc/group</code> if these aren't there already.
- </p></li><li class="step" title="Step 3"><p>
- <a class="indexterm" name="id384053"></a>
- <a class="indexterm" name="id384060"></a>
- You now need to change the permissions on Squid's <code class="constant">var</code>
- directory. Enter the following command:
-</p><pre class="screen">
-<code class="prompt">root# </code> chown -R squid /var/cache/squid
-</pre><p>
- </p></li><li class="step" title="Step 4"><p>
- <a class="indexterm" name="id384089"></a>
- <a class="indexterm" name="id384096"></a>
- Squid must also have control over its logging. Enter the following commands:
-</p><pre class="screen">
-<code class="prompt">root# </code> chown -R chown squid:squid /var/log/squid
-<code class="prompt">root# </code> chmod 770 /var/log/squid
-</pre><p>
- </p></li><li class="step" title="Step 5"><p>
- Finally, Squid must be able to write to its disk cache!
- Enter the following commands:
-</p><pre class="screen">
-<code class="prompt">root# </code> chown -R chown squid:squid /var/cache/squid
-<code class="prompt">root# </code> chmod 770 /var/cache/squid
-</pre><p>
- </p></li><li class="step" title="Step 6"><p>
- <a class="indexterm" name="id384153"></a>
- The <code class="filename">/etc/squid/squid.conf</code> file must be edited to include the lines from
- <a class="link" href="DomApps.html#etcsquidcfg" title="Example 12.4. Squid Configuration File Extract /etc/squid.conf [ADMINISTRATIVE PARAMETERS Section]">“Squid Configuration File Extract /etc/squid.conf [ADMINISTRATIVE PARAMETERS Section]”</a> and <a class="link" href="DomApps.html#etcsquid2" title="Example 12.5. Squid Configuration File extract File: /etc/squid.conf [AUTHENTICATION PARAMETERS Section]">“Squid Configuration File extract File: /etc/squid.conf [AUTHENTICATION PARAMETERS Section]”</a>.
- </p></li><li class="step" title="Step 7"><p>
- <a class="indexterm" name="id384186"></a>
- You must create Squid's cache directories before it may be run. Enter the following command:
-</p><pre class="screen">
-<code class="prompt">root# </code> squid -z
-</pre><p>
- </p></li><li class="step" title="Step 8"><p>
- Finally, start Squid and enjoy transparent Active Directory authentication.
- Enter the following command:
-</p><pre class="screen">
-<code class="prompt">root# </code> squid
-</pre><p>
- </p></li></ol></div><div class="example"><a name="etcsquidcfg"></a><p class="title"><b>Example 12.4. Squid Configuration File Extract <code class="filename">/etc/squid.conf</code> [ADMINISTRATIVE PARAMETERS Section]</b></p><div class="example-contents"><pre class="screen">
- cache_effective_user squid
- cache_effective_group squid
-</pre></div></div><br class="example-break"><div class="example"><a name="etcsquid2"></a><p class="title"><b>Example 12.5. Squid Configuration File extract File: <code class="filename">/etc/squid.conf</code> [AUTHENTICATION PARAMETERS Section]</b></p><div class="example-contents"><pre class="screen">
- auth_param ntlm program /usr/bin/ntlm_auth \
- --helper-protocol=squid-2.5-ntlmssp
- auth_param ntlm children 5
- auth_param ntlm max_challenge_reuses 0
- auth_param ntlm max_challenge_lifetime 2 minutes
- auth_param basic program /usr/bin/ntlm_auth \
- --helper-protocol=squid-2.5-basic
- auth_param basic children 5
- auth_param basic realm Squid proxy-caching web server
- auth_param basic credentialsttl 2 hours
- acl AuthorizedUsers proxy_auth REQUIRED
- http_access allow all AuthorizedUsers
-</pre></div></div><br class="example-break"></div><div class="sect2" title="Key Points Learned"><div class="titlepage"><div><div><h3 class="title"><a name="id384281"></a>Key Points Learned</h3></div></div></div><p>
- <a class="indexterm" name="id384289"></a>
- <a class="indexterm" name="id384296"></a>
- <a class="indexterm" name="id384303"></a>
- <a class="indexterm" name="id384310"></a>
- <a class="indexterm" name="id384321"></a>
- Microsoft Windows networking protocols permeate the spectrum of technologies that Microsoft
- Windows clients use, even when accessing traditional services such as Web browsers. Depending
- on whom you discuss this with, this is either good or bad. No matter how you might evaluate this,
- the use of NTLMSSP as the authentication protocol for Web proxy access has some advantages over
- the cookie-based authentication regime used by all competing browsers. It is Samba's implementation
- of NTLMSSP that makes it attractive to implement the solution that has been demonstrated in this chapter.
- </p></div></div><div class="sect1" title="Questions and Answers"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id384336"></a>Questions and Answers</h2></div></div></div><p>
- <a class="indexterm" name="id384344"></a>
- <a class="indexterm" name="id384351"></a>
- <a class="indexterm" name="id384358"></a>
- <a class="indexterm" name="id384365"></a>
- The development of the <code class="literal">ntlm_auth</code> module was first discussed in many Open Source circles
- in 2002. At the SambaXP conference in Goettingen, Germany, Mr. Francesco Chemolli demonstrated the use of
- <code class="literal">ntlm_auth</code> during one of the late developer meetings that took place. Since that time, the
- adoption of <code class="literal">ntlm_auth</code> has spread considerably.
- </p><p>
- The largest report from a site that uses Squid with <code class="literal">ntlm_auth</code>-based authentication
- support uses a dual processor server that has 2 GB of memory. It provides Web and FTP proxy services for 10,000
- users. Approximately 2,000 of these users make heavy use of the proxy services. According to the source, who
- wishes to remain anonymous, the sustained transaction load on this server hovers around 140 hits/sec. The following
- comments were made with respect to questions regarding the performance of this installation:
- </p><div class="blockquote"><blockquote class="blockquote"><p>
- [In our] EXTREMELY optimized environment . . . [the] performance impact is almost [nothing]. The <span class="quote">“<span class="quote">almost</span>”</span>
- part is due to the brain damage of the ntlm-over-http protocol definition. Suffice to say that its worst-case
- scenario triples the number of hits needed to perform the same transactions versus basic or digest auth[entication].
- </p></blockquote></div><p>
- You would be well-advised to recognize that all cache-intensive proxying solutions demand a lot of memory.
- Make certain that your Squid proxy server is equipped with sufficient memory to permit all proxy operations to run
- out of memory without invoking the overheads involved in the use of memory that has to be swapped to disk.
- </p><div class="qandaset" title="Frequently Asked Questions"><a name="id384423"></a><dl><dt> <a href="DomApps.html#id384430">
- What does Samba have to do with Web proxy serving?
- </a></dt><dt> <a href="DomApps.html#id384585">
- What other services does Samba provide?
- </a></dt><dt> <a href="DomApps.html#id384721">
- Does use of Samba (ntlm_auth) improve the performance of Squid?
- </a></dt></dl><table border="0" width="100%" summary="Q and A Set"><col align="left" width="1%"><col><tbody><tr class="question"><td align="left" valign="top"><a name="id384430"></a><a name="id384432"></a></td><td align="left" valign="top"><p>
- What does Samba have to do with Web proxy serving?
- </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
- <a class="indexterm" name="id384443"></a>
- <a class="indexterm" name="id384450"></a>
- <a class="indexterm" name="id384457"></a>
- <a class="indexterm" name="id384466"></a>
- <a class="indexterm" name="id384473"></a>
- To provide transparent interoperability between Windows clients and the network services
- that are used from them, Samba had to develop tools and facilities that deliver that feature. The benefit
- of Open Source software is that it can readily be reused. The current <code class="literal">ntlm_auth</code>
- module is basically a wrapper around authentication code from the core of the Samba project.
- </p><p>
- <a class="indexterm" name="id384492"></a>
- <a class="indexterm" name="id384499"></a>
- <a class="indexterm" name="id384508"></a>
- <a class="indexterm" name="id384517"></a>
- <a class="indexterm" name="id384526"></a>
- <a class="indexterm" name="id384533"></a>
- <a class="indexterm" name="id384540"></a>
- <a class="indexterm" name="id384546"></a>
- <a class="indexterm" name="id384553"></a>
- The <code class="literal">ntlm_auth</code> module supports basic plain-text authentication and NTLMSSP
- protocols. This module makes it possible for Web and FTP proxy requests to be authenticated without
- the user being interrupted via his or her Windows logon credentials. This facility is available with
- MS Windows Explorer and is one of the key benefits claimed for Microsoft Internet Information Server.
- There are a few open source initiatives to provide support for these protocols in the Apache Web server
- also.
- </p><p>
- <a class="indexterm" name="id384574"></a>
- The short answer is that by adding a wrapper around key authentication components of Samba, other
- projects (like Squid) can benefit from the labors expended in meeting user interoperability needs.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a name="id384585"></a><a name="id384588"></a></td><td align="left" valign="top"><p>
- What other services does Samba provide?
- </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
- <a class="indexterm" name="id384599"></a>
- <a class="indexterm" name="id384606"></a>
- <a class="indexterm" name="id384612"></a>
- <a class="indexterm" name="id384619"></a>
- <a class="indexterm" name="id384626"></a>
- Samba-3 is a file and print server. The core components that provide this functionality are <code class="literal">smbd</code>,
- <code class="literal">nmbd</code>, and the identity resolver daemon, <code class="literal">winbindd</code>.
- </p><p>
- <a class="indexterm" name="id384655"></a>
- <a class="indexterm" name="id384662"></a>
- Samba-3 is an SMB/CIFS client. The core component that provides this is called <code class="literal">smbclient</code>.
- </p><p>
- <a class="indexterm" name="id384679"></a>
- <a class="indexterm" name="id384685"></a>
- <a class="indexterm" name="id384692"></a>
- <a class="indexterm" name="id384699"></a>
- <a class="indexterm" name="id384706"></a>
- Samba-3 includes a number of helper tools, plug-in modules, utilities, and test and validation facilities.
- Samba-3 includes glue modules that help provide interoperability between MS Windows clients and UNIX/Linux
- servers and clients. It includes Winbind agents that make it possible to authenticate UNIX/Linux access attempts
- as well as logins to an SMB/CIFS authentication server backend. Samba-3 includes name service switch (NSS) modules
- to permit identity resolution via SMB/CIFS servers (Windows NT4/200x, Samba, and a host of other commercial
- server products).
- </p></td></tr><tr class="question"><td align="left" valign="top"><a name="id384721"></a><a name="id384723"></a></td><td align="left" valign="top"><p>
- Does use of Samba (<code class="literal">ntlm_auth</code>) improve the performance of Squid?
- </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
- Not really. Samba's <code class="literal">ntlm_auth</code> module handles only authentication. It requires that
- Squid make an external call to <code class="literal">ntlm_auth</code> and therefore actually incurs a
- little more overhead. Compared with the benefit obtained, that overhead is well worth enduring. Since
- Squid is a proxy server, and proxy servers tend to require lots of memory, it is good advice to provide
- sufficient memory when using Squid. Just add a little more to accommodate <code class="literal">ntlm_auth</code>.
- </p></td></tr></tbody></table></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="kerberos.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="RefSection.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="HA.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 11. Active Directory, Kerberos, and Security </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 13. Performance, Reliability, and Availability</td></tr></table></div></body></html>
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