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<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE chapter PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
<chapter id="secure">
<title>Secure Office Networking</title>
<para>
Congratulations, your Samba networking skills are developing nicely. You started out
with three simple networks in <link linkend="simple"/>, and then in <link linkend="small"/>
you designed and built a network that provides a high degree of flexibility, integrity,
and dependability. It was enough for the basic needs each was designed to fulfill. In
this chapter you address a more complex set of needs. The solution you explore
introduces you to basic features that are specific to Samba-3.
</para>
<para>
You should note that a working and secure solution could be implemented using Samba-2.2.x.
In the exercises presented here, you are gradually using more Samba-3-specific features,
so caution is advised for anyone who tries to use Samba-2.2.x with the guidance here given.
To avoid confusion, this book is all about Samba-3. Let's get the exercises in this
chapter underway.
</para>
<sect1>
<title>Introduction</title>
<para>
You have made Mr. Meany a very happy man. Recently he paid you a fat bonus for work
well done. It is one year since the last network upgrade. You have been quite busy.
Two months ago Mr. Meany gave approval to hire Christine Roberson, who has taken over
general network management. Soon she will provide primary user support. You have
demonstrated that you can delegate responsibility and can plan and execute according
to that plan. Above all, you have shown Mr. Meany that you are a responsible person.
Today is a big day. Mr. Meany called you to his office at 9 a.m. for news you never
expected: You are going to take charge of business operations. Mr. Meany
is retiring and has entrusted the business to your capable hands.
</para>
<para>
Mr. Meany may be retiring from this company, but not from work. He is taking the
opportunity to develop Abmas Accounting into a larger and more substantial company.
He says that it took him many years to learn that there is no future in just running
a business. He now realizes there is great personal satisfaction in the creation of
career opportunities for people in the local community. He wants to do more for others,
as he is doing for you. Today he spent a lot of time talking about his grand plan
for growth, which you will deal with in the chapters ahead.
</para>
<para>
Over the past year, the growth projections were exceeded. The network has grown to
meet the needs of 130 users. Along with growth, the demand for improved services
and better functionality has also developed. You are about to make an interim
improvement and then hand over all Help desk and network maintenance to Christine.
Christine has professional certifications in Microsoft Windows as well as in Linux;
she is a hard worker and quite likable. Christine does not want to manage the department
(although she manages well). She gains job satisfaction when left to sort things out.
Occasionally she wants to work with you on a challenging problem. When you told her
about your move, she almost resigned, although she was reassured that a new manager would
be hired to run Information Technology, and she would be responsible only for operations.
</para>
<sect2>
<title>Assignment Tasks</title>
<para>
You promised the staff Internet services including Web browsing, electronic mail, virus
protection, and a company Web site. Christine is eager to help turn the vision into
reality. Let's see how close you can get to the promises made.
</para>
<para>
The network you are about to deliver will service 130 users today. Within a year,
Abmas will aquire another company. Mr. Meany claims that within 2 years there will be
well over 500 users on the network. You have bought into the big picture, so prepare
for growth. You have purchased a new server and will implement a new network infrastructure.
</para>
<para>
You have decided to not recycle old network components. The only items that will be
carried forward are notebook computers. You offered staff new notebooks, but not
one person wanted the disruption for what was perceived as a marginal update.
You decided to give everyone, even the notebook user, a new desktop computer.
</para>
<para>
You procured a DSL Internet connection that provides 1.5 Mb/sec (bidirectional)
and a 10 Mb/sec ethernet port. You registered the domain
<constant>abmas.us</constant>, and the Internet Service Provider (ISP) is supplying
secondary DNS. Information furnished by your ISP is shown in <link linkend="chap4netid"/>.
</para>
<para>
It is of paramount priority that under no circumstances will Samba offer
service access from an Internet connection. You are paying an ISP to
give, as part of its value-added services, full firewall protection for your
connection to the outside world. The only services allowed in from
the Internet side are the following destination ports: <constant>http/https (ports
80 and 443), email (port 25), DNS (port 53)</constant>. All Internet traffic
will be allowed out after network address translation (NAT). No internal IP addresses
are permitted through the NAT filter because complete privacy of internal network
operations must be assured.
</para>
<table id="chap4netid">
<title>Abmas.US ISP Information</title>
<tgroup cols="2">
<colspec align="left"/>
<colspec align="center"/>
<thead>
<row>
<entry>Parameter</entry>
<entry>Value</entry>
</row>
</thead>
<tbody>
<row>
<entry>Server IP Address</entry>
<entry>123.45.67.66</entry>
</row>
<row>
<entry>DSL Device IP Address</entry>
<entry>123.45.67.65</entry>
</row>
<row>
<entry>Network Address</entry>
<entry>123.45.67.64/30</entry>
</row>
<row>
<entry>Gateway Address</entry>
<entry>123.45.54.65</entry>
</row>
<row>
<entry>Primary DNS Server</entry>
<entry>123.45.54.65</entry>
</row>
<row>
<entry>Secondary DNS Server</entry>
<entry>123.45.54.32</entry>
</row>
<row>
<entry>Forwarding DNS Server</entry>
<entry>123.45.12.23</entry>
</row>
</tbody>
</tgroup>
</table>
<figure id="ch04net">
<title>Abmas Network Topology &smbmdash; 130 Users</title>
<imagefile scale="65">chap4-net</imagefile>
</figure>
<para>
Christine recommended that desktop systems should be installed from a single cloned
master system that has a minimum of locally installed software and loads all software
off a central application server. The benefit of having the central application server
is that it allows single-point maintenance of all business applications, a more
efficient way to manage software. She further recommended installation of antivirus
software on workstations as well as on the Samba server. Christine knows the dangers
of potential virus infection and insists on a comprehensive approach to detective
as well as corrective action to protect network operations.
</para>
<para>
A significant concern is the problem of managing company growth. Recently, a number
of users had to share a PC while waiting for new machines to arrive. This presented
some problems with desktop computers and software installation into the new users'
desktop profiles.
</para>
</sect2>
</sect1>
<sect1>
<title>Dissection and Discussion</title>
<para>
Many of the conclusions you draw here are obvious. Some requirements are not very clear
or may simply be your means of drawing the most out of Samba-3. Much can be done more simply
than you will demonstrate here, but keep in mind that the network must scale to at least 500
users. This means that some functionality will be overdesigned for the current 130-user
environment.
</para>
<sect2>
<title>Technical Issues</title>
<para>
In this exercise we use a 24-bit subnet mask for the two local networks. This,
of course, limits our network to a maximum of 253 usable IP addresses. The network
address range chosen is one assigned by RFC1918 for private networks.
When the number of users on the network begins to approach the limit of usable
addresses, it is a good idea to switch to a network address specified in RFC1918
in the 172.16.0.0/16 range. This is done in subsequent chapters.
</para>
<para>
<indexterm><primary>tdbsam</primary></indexterm>
<indexterm><primary>smbpasswd</primary></indexterm>
The high growth rates projected are a good reason to use the <constant>tdbsam</constant>
passdb backend. The use of <constant>smbpasswd</constant> for the backend may result in
performance problems. The <constant>tdbsam</constant> passdb backend offers features that
are not available with the older, flat ASCII-based <constant>smbpasswd</constant> database.
</para>
<para>
<indexterm><primary>risk</primary></indexterm>
The proposed network design uses a single server to act as an Internet services host for
electronic mail, Web serving, remote administrative access via SSH,
Samba-based file and print services. This design is often chosen by sites that feel
they cannot afford or justify the cost or overhead of having separate servers. It must
be realized that if security of this type of server should ever be violated (compromised),
the whole network and all data is at risk. Many sites continue to choose this type
of solution; therefore, this chapter provides detailed coverage of key implementation
aspects.
</para>
<para>
Samba will be configured to specifically not operate on the Ethernet interface that is
directly connected to the Internet.
</para>
<para>
<indexterm><primary>iptables</primary></indexterm>
<indexterm><primary>NAT</primary></indexterm>
<indexterm><primary>Network Address Translation</primary><see>NAT</see></indexterm>
<indexterm><primary>firewall</primary></indexterm>
You know that your ISP is providing full firewall services, but you cannot rely on that.
Always assume that human error will occur, so be prepared by using Linux firewall facilities
based on <command>iptables</command> to effect NAT. Block all
incoming traffic except to permitted well-known ports. You must also allow incoming packets
to establish outgoing connections. You will permit all internal outgoing requests.
</para>
<para>
The configuration of Web serving, Web proxy services, electronic mail, and the details of
generic antivirus handling are beyond the scope of this book and therefore are not
covered except insofar as this affects Samba-3.
</para>
<para>
<indexterm><primary>login</primary></indexterm>
Notebook computers are configured to use a network login when in the office and a
local account to log in while away from the office. Users store all work done in
transit (away from the office) by using a local share for work files. Standard procedures
dictate that on completion of the work that necessitates mobile file access, all
work files are moved back to secure storage on the office server. Staff is instructed
to not carry on any company notebook computer any files that are not absolutely required.
This is a preventative measure to protect client information as well as private business
records.
</para>
<para>
<indexterm><primary>application server</primary></indexterm>
All applications are served from the central server from a share called <constant>apps</constant>.
Microsoft Office XP Professional and OpenOffice 1.1.0 will be installed using a network
(or administrative) installation. Accounting and financial management software can also
be run only from the central application server. Notebook users are provided with
locally installed applications on a need-to-have basis only.
</para>
<para>
<indexterm><primary>roaming profiles</primary></indexterm>
The introduction of roaming profiles support means that users can move between
desktop computer systems without constraint while retaining full access to their data.
The desktop travels with them as they move.
</para>
<para>
<indexterm><primary>DNS</primary></indexterm>
The DNS server implementation must now address both internal and external
needs. You forward DNS lookups to your ISP-provided server as well as the
<constant>abmas.us</constant> external secondary DNS server.
</para>
<para>
<indexterm><primary>dynamic DNS</primary></indexterm>
<indexterm><primary>DDNS</primary><see>dynamic DNS</see></indexterm>
<indexterm><primary>DHCP server</primary></indexterm>
Compared with the DHCP server configuration in <link linkend="small"/>, <link linkend="dhcp01"/>, the
configuration used in this example has to deal with the presence of an Internet connection.
The scope set for it ensures that no DHCP services will be offered on the external
connection. All printers are configured as DHCP clients so that the DHCP server assigns
the printer a fixed IP address by way of the Ethernet interface (MAC) address. One additional
feature of this DHCP server configuration file is the inclusion of parameters to allow dynamic
DNS (DDNS) operation.
</para>
<para>
This is the first implementation that depends on a correctly functioning DNS server.
Comprehensive steps are included to provide for a fully functioning DNS server that also
is enabled for DDNS operation. This means that DHCP clients can be autoregistered
with the DNS server.
</para>
<para>
You are taking the opportunity to manually set the netbios name of the Samba server to
a name other than what will be automatically resolved. You are doing this to ensure that
the machine has the same NetBIOS name on both network segments.
</para>
<para>
As in the previous network configuration, printing in this network configuration uses
direct raw printing (i.e., no smart printing and no print driver autodownload to Windows
clients). Printer drivers are installed on the Windows client manually. This is not
a problem because Christine is to install and configure one single workstation and
then clone that configuration, using Norton Ghost, to all workstations. Each machine is
identical, so this should pose no problem.
</para>
<sect3>
<title>Hardware Requirements</title>
<para>
<indexterm><primary>memory requirements</primary></indexterm>
This server runs a considerable number of services. From similarly configured Linux
installations, the approximate calculated memory requirements are as shown in
<link linkend="ch4memoryest"/>.
<example id="ch4memoryest">
<title>Estimation of Memory Requirements</title>
<screen>
Application Memory per User 130 Users 500 Users
Name (MBytes) Total MBytes Total MBytes
----------- --------------- ------------ ------------
DHCP 2.5 3 3
DNS 16.0 16 16
Samba (nmbd) 16.0 16 16
Samba (winbind) 16.0 16 16
Samba (smbd) 4.0 520 2000
Apache 10.0 (20 User) 200 200
CUPS 3.5 16 32
Basic OS 256.0 256 256
-------------- --------------
Total: 1043 MBytes 2539 MBytes
-------------- --------------
</screen>
</example>
You should add a safety margin of at least 50% to these estimates. The minimum
system memory recommended for initial startup 1 GB, but to permit the system
to scale to 500 users, it makes sense to provision the machine with 4 GB memory.
An initial configuration with only 1 GB memory would lead to early performance complaints
as the system load builds up. Given the low cost of memory, it does not make sense to
compromise in this area.
</para>
<para>
<indexterm><primary>bandwidth calculations</primary></indexterm>
Aggregate input/output loads should be considered for sizing network configuration as
well as disk subsystems. For network bandwidth calculations, one would typically use an
estimate of 0.1 MB/sec per user. This suggests that 100-Base-T (approx. 10 MB/sec)
would deliver below acceptable capacity for the initial user load. It is therefore a good
idea to begin with 1 Gb Ethernet cards for the two internal networks, each attached
to a 1 Gb Ethernet switch that provides connectivity to an expandable array of 100-Base-T
switched ports.
</para>
<para>
<indexterm><primary>network segments</primary></indexterm>
<indexterm><primary>RAID</primary></indexterm>
Considering the choice of 1 Gb Ethernet interfaces for the two local network segments,
the aggregate network I/O capacity will be 2100 Mb/sec (about 230 MB/sec), an I/O
demand that would require a fast disk storage I/O capability. Peak disk throughput is
limited by the disk subsystem chosen. It is desirable to provide the maximum
I/O bandwidth affordable. If a low-cost solution must be chosen,
3Ware IDE RAID Controllers are a good choice. These controllers can be fitted into a
64-bit, 66 MHz PCI-X slot. They appear to the operating system as a high-speed SCSI
controller that can operate at the peak of the PCI-X bandwidth (approximately 450 MB/sec).
Alternative SCSI-based hardware RAID controllers should also be considered. Alternately,
it makes sense to purchase well-known, branded hardware that has appropriate performance
specifications. As a minimum, one should attempt to provide a disk subsystem that can
deliver I/O rates of at least 100 MB/sec.
</para>
<para>
Disk storage requirements may be calculated as shown in <link linkend="ch4diskest"/>.
<example id="ch4diskest">
<title>Estimation of Disk Storage Requirements</title>
<screen>
Corporate Data: 100 MBytes/user per year
Email Storage: 500 MBytes/user per year
Applications: 5000 MBytes
Safety Buffer: At least 50%
Given 500 Users and 2 years:
-----------------------------
Corporate Data: 2 x 100 x 500 = 100000 MBytes = 100 GBytes
Email Storage: 2 x 500 x 500 = 500000 MBytes = 500 GBytes
Applications: 5000 MBytes = 5 GBytes
----------------------------
Total: 605 GBytes
Add 50% buffer 303 GBytes
Recommended Storage: 908 GBytes
</screen>
</example>
<indexterm><primary>storage capacity</primary></indexterm>
The preferred storage capacity should be approximately 1 Terabyte. Use of RAID level 5
with two hot spare drives would require an 8-drive by 200 GB capacity per drive array.
</para>
</sect3>
</sect2>
<sect2>
<title>Political Issues</title>
<para>
Your industry is coming under increasing accountability pressures. Increased paranoia
is necessary so you can demonstrate that you have acted with due diligence. You must
not trust your Internet connection.
</para>
<para>
Apart from permitting more efficient management of business applications through use of
an application server, your primary reason for the decision to implement this is that it
gives you greater control over software licensing.
</para>
<para>
<indexterm><primary>Outlook Express</primary></indexterm>
You are well aware that the current configuration results in some performance issues
as the size of the desktop profile grows. Given that users use Microsoft Outlook
Express, you know that the storage implications of the <constant>.PST</constant> file
is something that needs to be addressed later.
</para>
</sect2>
</sect1>
<sect1>
<title>Implementation</title>
<para>
<link linkend="ch04net"/> demonstrates the overall design of the network that you will implement.
</para>
<para>
The information presented here assumes that you are already familiar with many basic steps.
As this stands, the details provided already extend well beyond just the necessities of
Samba configuration. This decision is deliberate to ensure that key determinants
of a successful installation are not overlooked. This is the last case that documents
the finite minutiae of DHCP and DNS server configuration. Beyond the information provided
here, there are many other good reference books on these subjects.
</para>
<para>
The &smb.conf; file has the following noteworthy features:
</para>
<itemizedlist>
<listitem><para>
The NetBIOS name of the Samba server is set to <constant>DIAMOND</constant>.
</para></listitem>
<listitem><para>
The Domain name is set to <constant>PROMISES</constant>.
</para></listitem>
<listitem><para>
<indexterm><primary>broadcast messages</primary></indexterm>
<indexterm><primary>interfaces</primary></indexterm>
<indexterm><primary>bind interfaces only</primary></indexterm>
Ethernet interface <constant>eth0</constant> is attached to the Internet connection
and is externally exposed. This interface is explicitly not available for Samba to use.
Samba listens on this interface for broadcast messages but does not broadcast any
information on <constant>eth0</constant>, nor does it accept any connections from it.
This is achieved by way of the <parameter>interfaces</parameter> parameter and the
<parameter>bind interfaces only</parameter> entry.
</para></listitem>
<listitem><para>
<indexterm><primary>passdb backend</primary></indexterm>
<indexterm><primary>tdbsam</primary></indexterm>
<indexterm><primary>binary database</primary></indexterm>
The <parameter>passdb backend</parameter> parameter specifies the creation and use
of the <constant>tdbsam</constant> password backend. This is a binary database that
has excellent scalability for a large number of user account entries.
</para></listitem>
<listitem><para>
<indexterm><primary>WINS serving</primary></indexterm>
<indexterm><primary>wins support</primary></indexterm>
<indexterm><primary>name resolve order</primary></indexterm>
WINS serving is enabled by the <smbconfoption name="wins support">Yes</smbconfoption>,
and name resolution is set to use it by means of the
<smbconfoption name="name resolve order">wins bcast hosts</smbconfoption> entry.
</para></listitem>
<listitem><para>
<indexterm><primary>time server</primary></indexterm>
The Samba server is configured for use by Windows clients as a time server.
</para></listitem>
<listitem><para>
<indexterm><primary>CUPS</primary></indexterm>
<indexterm><primary>printing</primary></indexterm>
<indexterm><primary>printcap name</primary></indexterm>
Samba is configured to directly interface with CUPS via the direct internal interface
that is provided by CUPS libraries. This is achieved with the
<smbconfoption name="printing">CUPS</smbconfoption> as well as the
<smbconfoption name="printcap name">CUPS</smbconfoption> entries.
</para></listitem>
<listitem><para>
<indexterm><primary>user management</primary></indexterm>
<indexterm><primary>group management</primary></indexterm>
<indexterm><primary>SRVTOOLS.EXE</primary></indexterm>
External interface scripts are provided to enable Samba to interface smoothly to
essential operating system functions for user and group management. This is important
to enable workstations to join the Domain and is also important so that you can use
the Windows NT4 Domain User Manager as well as the Domain Server Manager. These tools
are provided as part of the <filename>SRVTOOLS.EXE</filename> toolkit that can be
downloaded from the Microsoft FTP
<ulink url="ftp://ftp.microsoft.com/Softlib/MSLFILES/SRVTOOLS.EXE">site</ulink>.
</para></listitem>
<listitem><para>
<indexterm><primary>User Mode</primary></indexterm>
The &smb.conf; file specifies that the Samba server will operate in (default) <parameter>
security = user</parameter> mode<footnote><para>See <emphasis>TOSHARG2</emphasis>, Chapter 3.
This is necessary so that Samba can act as a Domain Controller (PDC); see
<emphasis>TOSHARG2</emphasis>, Chapter 4, for additional information.</para></footnote>
(User Mode).
</para></listitem>
<listitem><para>
<indexterm><primary>logon services</primary></indexterm>
<indexterm><primary>logon script</primary></indexterm>
Domain logon services as well as a Domain logon script are specified. The logon script
will be used to add robustness to the overall network configuration.
</para></listitem>
<listitem><para>
<indexterm><primary>roaming profiles</primary></indexterm>
<indexterm><primary>logon path</primary></indexterm>
<indexterm><primary>profile share</primary></indexterm>
Roaming profiles are enabled through the specification of the parameter,
<smbconfoption name="logon path">\\%L\profiles\%U</smbconfoption>. The value of this parameter translates the
<constant>%L</constant> to the name by which the Samba server is called by the client (for this
configuration, it translates to the name <constant>DIAMOND</constant>), and the <constant>%U</constant>
will translate to the name of the user within the context of the connection made to the profile share.
It is the administrator's responsibility to ensure there is a directory in the root of the
profile share for each user. This directory must be owned by the user also. An exception to this
requirement is when a profile is created for group use.
</para></listitem>
<listitem><para>
<indexterm><primary>virus</primary></indexterm>
<indexterm><primary>opportunistic locking</primary></indexterm>
Precautionary veto is effected for particular Windows file names that have been targeted by
virus-related activity. Additionally, Microsoft Office files are vetoed from opportunistic locking
controls. This should help to prevent lock contention-related file access problems.
</para></listitem>
<listitem><para>
Every user has a private home directory on the UNIX/Linux host. This is mapped to
a network drive that is the same for all users.
</para></listitem>
</itemizedlist>
<para>
The configuration of the server is the most complex so far. The following steps are used:
</para>
<orderedlist numeration="arabic">
<listitem><para>
Basic System Configuration
</para></listitem>
<listitem><para>
Samba Configuration
</para></listitem>
<listitem><para>
DHCP and DNS Server Configuration
</para></listitem>
<listitem><para>
Printer Configuration
</para></listitem>
<listitem><para>
Process Start-up Configuration
</para></listitem>
<listitem><para>
Validation
</para></listitem>
<listitem><para>
Application Share Configuration
</para></listitem>
<listitem><para>
Windows Client Configuration
</para></listitem>
</orderedlist>
<para>
The following sections cover each step in logical and defined detail.
</para>
<sect2 id="ch4bsc">
<title>Basic System Configuration</title>
<para>
<indexterm><primary>SUSE Enterprise Linux Server</primary></indexterm>
The preparation in this section assumes that your SUSE Enterprise Linux Server 8.0 system has been
freshly installed. It prepares basic files so that the system is ready for comprehensive
operation in line with the network diagram shown in <link linkend="ch04net"/>.
</para>
<procedure>
<title>Server Configuration Steps</title>
<step><para>
<indexterm><primary>hostname</primary></indexterm>
Using the UNIX/Linux system tools, name the server <constant>server.abmas.us</constant>.
Verify that your hostname is correctly set by running:
<screen>
&rootprompt; uname -n
server
</screen>
An alternate method to verify the hostname is:
<screen>
&rootprompt; hostname -f
server.abmas.us
</screen>
</para></step>
<step><para>
<indexterm><primary>/etc/hosts</primary></indexterm>
<indexterm><primary>localhost</primary></indexterm>
Edit your <filename>/etc/hosts</filename> file to include the primary names and addresses
of all network interfaces that are on the host server. This is necessary so that during
startup the system can resolve all its own names to the IP address prior to
startup of the DNS server. An example of entries that should be in the
<filename>/etc/hosts</filename> file is:
<screen>
127.0.0.1 localhost
192.168.1.1 sleeth1.abmas.biz sleeth1 diamond
192.168.2.1 sleeth2.abmas.biz sleeth2
123.45.67.66 server.abmas.us server
</screen>
You should check the startup order of your system. If the CUPS print server is started before
the DNS server (<command>named</command>), you should also include an entry for the printers
in the <filename>/etc/hosts</filename> file, as follows:
<screen>
192.168.1.20 qmsa.abmas.biz qmsa
192.168.1.30 hplj6a.abmas.biz hplj6a
192.168.2.20 qmsf.abmas.biz qmsf
192.168.2.30 hplj6f.abmas.biz hplj6f
</screen>
<indexterm><primary>named</primary></indexterm>
<indexterm><primary>cupsd</primary></indexterm>
<indexterm><primary>daemon</primary></indexterm>
The printer entries are not necessary if <command>named</command> is started prior to
startup of <command>cupsd</command>, the CUPS daemon.
</para></step>
<step><para>
<indexterm><primary>/etc/rc.d/boot.local</primary></indexterm>
<indexterm><primary>IP forwarding</primary></indexterm>
<indexterm><primary>/proc/sys/net/ipv4/ip_forward</primary></indexterm>
The host server is acting as a router between the two internal network segments as well
as for all Internet access. This necessitates that IP forwarding be enabled. This can be
achieved by adding to the <filename>/etc/rc.d/boot.local</filename> an entry as follows:
<screen>
echo 1 > /proc/sys/net/ipv4/ip_forward
</screen>
To ensure that your kernel is capable of IP forwarding during configuration, you may
wish to execute that command manually also. This setting permits the Linux system to
act as a router.<footnote><para>You may want to do the echo command last and include
"0" in the init scripts, since it opens up your network for a short time.</para></footnote>
</para></step>
<step><para>
<indexterm><primary>firewall</primary></indexterm>
<indexterm><primary>abmas-netfw.sh</primary></indexterm>
Installation of a basic firewall and NAT facility is necessary.
The following script can be installed in the <filename>/usr/local/sbin</filename>
directory. It is executed from the <filename>/etc/rc.d/boot.local</filename> startup
script. In your case, this script is called <filename>abmas-netfw.sh</filename>. The
script contents are shown in <link linkend="ch4natfw"/>.
<example id="ch4natfw">
<title>NAT Firewall Configuration Script</title>
<screen>
#!/bin/sh
echo -e "\n\nLoading NAT firewall.\n"
IPTABLES=/usr/sbin/iptables
EXTIF="eth0"
INTIFA="eth1"
INTIFB="eth2"
/sbin/depmod -a
/sbin/modprobe ip_tables
/sbin/modprobe ip_conntrack
/sbin/modprobe ip_conntrack_ftp
/sbin/modprobe iptable_nat
/sbin/modprobe ip_nat_ftp
$IPTABLES -P INPUT DROP
$IPTABLES -F INPUT
$IPTABLES -P OUTPUT ACCEPT
$IPTABLES -F OUTPUT
$IPTABLES -P FORWARD DROP
$IPTABLES -F FORWARD
$IPTABLES -A INPUT -i lo -j ACCEPT
$IPTABLES -A INPUT -i $INTIFA -j ACCEPT
$IPTABLES -A INPUT -i $INTIFB -j ACCEPT
$IPTABLES -A INPUT -i $EXTIF -m state --state ESTABLISHED,RELATED -j ACCEPT
# Enable incoming traffic for: SSH, SMTP, DNS(tcp), HTTP, HTTPS
for i in 22 25 53 80 443
do
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $i -j ACCEPT
done
# Allow DNS(udp)
$IPTABLES -A INPUT -i $EXTIF -p udp -dport 53 -j ACCEPT
echo "Allow all connections OUT and only existing and specified ones IN"
$IPTABLES -A FORWARD -i $EXTIF -o $INTIFA -m state \
--state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -o $INTIFB -m state \
--state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $INTIFA -o $EXTIF -j ACCEPT
$IPTABLES -A FORWARD -i $INTIFB -o $EXTIF -j ACCEPT
$IPTABLES -A FORWARD -j LOG
echo " Enabling SNAT (MASQUERADE) functionality on $EXTIF"
$IPTABLES -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE
echo "1" > /proc/sys/net/ipv4/ip_forward
echo -e "\nNAT firewall done.\n"
</screen>
</example>
</para></step>
<step><para>
Execute the following to make the script executable:
<screen>
&rootprompt; chmod 755 /usr/local/sbin/abmas-natfw.sh
</screen>
You must now edit <filename>/etc/rc.d/boot.local</filename> to add an entry
that runs your <command>abmas-natfw.sh</command> script. The following
entry works for you:
<screen>
#! /bin/sh
#
# Copyright (c) 2002 SUSE Linux AG Nuernberg, Germany.
# All rights reserved.
#
# Author: Werner Fink, 1996
# Burchard Steinbild, 1996
#
# /etc/init.d/boot.local
#
# script with local commands to be executed from init on system startup
#
# Here you should add things that should happen directly after booting
# before we're going to the first run level.
#
/usr/local/sbin/abmas-natfw.sh
</screen>
</para></step>
</procedure>
<para>
<indexterm><primary>/etc/hosts</primary></indexterm>
The server is now ready for Samba configuration. During the validation step, you remove
the entry for the Samba server <constant>diamond</constant> from the <filename>/etc/hosts</filename>
file. This is done after you are satisfied that DNS-based name resolution is functioning correctly.
</para>
</sect2>
<sect2>
<title>Samba Configuration</title>
<para>
When you have completed this section, the Samba server is ready for testing and validation;
however, testing and validation have to wait until DHCP, DNS, and printing (CUPS) services have
been configured.
</para>
<procedure>
<title>Samba Configuration Steps</title>
<step><para>
Install the Samba-3 binary RPM from the Samba-Team FTP site. Assuming that the binary
RPM file is called <filename>samba-3.0.20-1.i386.rpm</filename>, one way to install this
file is as follows:
<screen>
&rootprompt; rpm -Uvh samba-3.0.20-1.i386.rpm
</screen>
This operation must be performed while logged in as the <command>root</command> user.
Successful operation is clearly indicated. If this installation should fail for any reason,
refer to the operating system manufacturer's documentation for guidance.
</para></step>
<step><para>
Install the &smb.conf; file shown in <link linkend="promisnet"/>, <link linkend="promisnetsvca"/>,
and <link linkend="promisnetsvcb"/>. Concatenate (join) all three files to make a single &smb.conf;
file. The final, fully qualified path for this file should be <filename>/etc/samba/smb.conf</filename>.
<example id="promisnet">
<title>130 User Network with <emphasis>tdbsam</emphasis> &smbmdash; [globals] Section</title>
<smbconfblock>
<smbconfcomment>Global parameters</smbconfcomment>
<smbconfsection name="[global]"/>
<smbconfoption name="workgroup">PROMISES</smbconfoption>
<smbconfoption name="netbios name">DIAMOND</smbconfoption>
<smbconfoption name="interfaces">eth1, eth2, lo</smbconfoption>
<smbconfoption name="bind interfaces only">Yes</smbconfoption>
<smbconfoption name="passdb backend">tdbsam</smbconfoption>
<smbconfoption name="pam password change">Yes</smbconfoption>
<smbconfoption name="passwd program">/usr/bin/passwd %u</smbconfoption>
<smbconfoption name="passwd chat">*New*Password* %n\n *Re-enter*new*password*%n\n *Password*changed*</smbconfoption>
<smbconfoption name="username map">/etc/samba/smbusers</smbconfoption>
<smbconfoption name="unix password sync">Yes</smbconfoption>
<smbconfoption name="log level">1</smbconfoption>
<smbconfoption name="syslog">0</smbconfoption>
<smbconfoption name="log file">/var/log/samba/%m</smbconfoption>
<smbconfoption name="max log size">50</smbconfoption>
<smbconfoption name="smb ports">139</smbconfoption>
<smbconfoption name="name resolve order">wins bcast hosts</smbconfoption>
<smbconfoption name="time server">Yes</smbconfoption>
<smbconfoption name="printcap name">CUPS</smbconfoption>
<smbconfoption name="show add printer wizard">No</smbconfoption>
<smbconfoption name="add user script">/usr/sbin/useradd -m '%u'</smbconfoption>
<smbconfoption name="delete user script">/usr/sbin/userdel -r '%u'</smbconfoption>
<smbconfoption name="add group script">/usr/sbin/groupadd '%g'</smbconfoption>
<smbconfoption name="delete group script">/usr/sbin/groupdel '%g'</smbconfoption>
<smbconfoption name="add user to group script">/usr/sbin/usermod -G '%g' '%u'</smbconfoption>
<smbconfoption name="add machine script">/usr/sbin/useradd -s /bin/false -d /tmp '%u'</smbconfoption>
<smbconfoption name="shutdown script">/var/lib/samba/scripts/shutdown.sh</smbconfoption>
<smbconfoption name="abort shutdown script">/sbin/shutdown -c</smbconfoption>
<smbconfoption name="logon script">scripts\logon.bat</smbconfoption>
<smbconfoption name="logon path">\\%L\profiles\%U</smbconfoption>
<smbconfoption name="logon drive">X:</smbconfoption>
<smbconfoption name="logon home">\\%L\%U</smbconfoption>
<smbconfoption name="domain logons">Yes</smbconfoption>
<smbconfoption name="preferred master">Yes</smbconfoption>
<smbconfoption name="wins support">Yes</smbconfoption>
<smbconfoption name="utmp">Yes</smbconfoption>
<smbconfoption name="map acl inherit">Yes</smbconfoption>
<smbconfoption name="printing">cups</smbconfoption>
<smbconfoption name="cups options">Raw</smbconfoption>
<smbconfoption name="veto files">/*.eml/*.nws/*.{*}/</smbconfoption>
<smbconfoption name="veto oplock files">/*.doc/*.xls/*.mdb/</smbconfoption>
</smbconfblock>
</example>
<example id="promisnetsvca">
<title>130 User Network with <emphasis>tdbsam</emphasis> &smbmdash; Services Section Part A</title>
<smbconfblock>
<smbconfsection name="[homes]"/>
<smbconfoption name="comment">Home Directories</smbconfoption>
<smbconfoption name="valid users">%S</smbconfoption>
<smbconfoption name="read only">No</smbconfoption>
<smbconfoption name="browseable">No</smbconfoption>
<smbconfsection name="[printers]"/>
<smbconfoption name="comment">SMB Print Spool</smbconfoption>
<smbconfoption name="path">/var/spool/samba</smbconfoption>
<smbconfoption name="guest ok">Yes</smbconfoption>
<smbconfoption name="printable">Yes</smbconfoption>
<smbconfoption name="use client driver">Yes</smbconfoption>
<smbconfoption name="default devmode">Yes</smbconfoption>
<smbconfoption name="browseable">No</smbconfoption>
<smbconfsection name="[netlogon]"/>
<smbconfoption name="comment">Network Logon Service</smbconfoption>
<smbconfoption name="path">/var/lib/samba/netlogon</smbconfoption>
<smbconfoption name="guest ok">Yes</smbconfoption>
<smbconfoption name="locking">No</smbconfoption>
<smbconfsection name="[profiles]"/>
<smbconfoption name="comment">Profile Share</smbconfoption>
<smbconfoption name="path">/var/lib/samba/profiles</smbconfoption>
<smbconfoption name="read only">No</smbconfoption>
<smbconfoption name="profile acls">Yes</smbconfoption>
<smbconfsection name="[accounts]"/>
<smbconfoption name="comment">Accounting Files</smbconfoption>
<smbconfoption name="path">/data/accounts</smbconfoption>
<smbconfoption name="read only">No</smbconfoption>
</smbconfblock>
</example>
<example id="promisnetsvcb">
<title>130 User Network with <emphasis>tdbsam</emphasis> &smbmdash; Services Section Part B</title>
<smbconfblock>
<smbconfsection name="[service]"/>
<smbconfoption name="comment">Financial Services Files</smbconfoption>
<smbconfoption name="path">/data/service</smbconfoption>
<smbconfoption name="read only">No</smbconfoption>
<smbconfsection name="[pidata]"/>
<smbconfoption name="comment">Property Insurance Files</smbconfoption>
<smbconfoption name="path">/data/pidata</smbconfoption>
<smbconfoption name="read only">No</smbconfoption>
<smbconfsection name="[apps]"/>
<smbconfoption name="comment">Application Files</smbconfoption>
<smbconfoption name="path">/apps</smbconfoption>
<smbconfoption name="read only">Yes</smbconfoption>
<smbconfoption name="admin users">bjordan</smbconfoption>
</smbconfblock>
</example>
</para></step>
<step><para>
<indexterm><primary>administrator</primary></indexterm><indexterm>
<primary>smbpasswd</primary>
</indexterm>
Add the <constant>root</constant> user to the password backend as follows:
<screen>
&rootprompt; smbpasswd -a root
New SMB password: XXXXXXXX
Retype new SMB password: XXXXXXXX
&rootprompt;
</screen>
The <constant>root</constant> account is the UNIX equivalent of the Windows Domain Administrator.
This account is essential in the regular maintenance of your Samba server. It must never be
deleted. If for any reason the account is deleted, you may not be able to recreate this account
without considerable trouble.
</para></step>
<step><para>
<indexterm><primary>username map</primary></indexterm>
Create the username map file to permit the <constant>root</constant> account to be called
<constant>Administrator</constant> from the Windows network environment. To do this, create
the file <filename>/etc/samba/smbusers</filename> with the following contents:
<screen>
####
# User mapping file
####
# File Format
# -----------
# Unix_ID = Windows_ID
#
# Examples:
# root = Administrator
# janes = "Jane Smith"
# jimbo = Jim Bones
#
# Note: If the name contains a space it must be double quoted.
# In the example above the name 'jimbo' will be mapped to Windows
# user names 'Jim' and 'Bones' because the space was not quoted.
#######################################################################
root = Administrator
####
# End of File
####
</screen>
</para></step>
<step><para>
<indexterm><primary>initGrps.sh</primary></indexterm>
<indexterm><primary>net</primary><secondary>groupmap</secondary><tertiary>add</tertiary></indexterm>
<indexterm><primary>net</primary><secondary>groupmap</secondary><tertiary>modify</tertiary></indexterm>
<indexterm><primary>net</primary><secondary>groupmap</secondary><tertiary>list</tertiary></indexterm>
Create and map Windows Domain Groups to UNIX groups. A sample script is provided in <link linkend="small"/>,
<link linkend="initGrps"/>. Create a file containing this script. We called ours
<filename>/etc/samba/initGrps.sh</filename>. Set this file so it can be executed,
and then execute the script. Sample output should be as follows:
<example id="ch4initGrps">
<title>Script to Map Windows NT Groups to UNIX Groups</title>
<indexterm><primary>initGrps.sh</primary></indexterm>
<screen>
#!/bin/bash
#
# initGrps.sh
#
# Create UNIX groups
groupadd acctsdep
groupadd finsrvcs
# Map Windows Domain Groups to UNIX groups
net groupmap add ntgroup="Domain Admins" unixgroup=root type=d
net groupmap add ntgroup="Domain Users" unixgroup=users type=d
net groupmap add ntgroup="Domain Guests" unixgroup=nobody type=d
# Add Functional Domain Groups
net groupmap add ntgroup="Accounts Dept" unixgroup=acctsdep type=d
net groupmap add ntgroup="Financial Services" unixgroup=finsrvcs type=d
net groupmap add ntgroup="Insurance Group" unixgroup=piops type=d
# Map Windows NT machine local groups to local UNIX groups
# Mapping of local groups is not necessary and not functional
# for this installation.
</screen>
</example>
<screen>
&rootprompt; chmod 755 initGrps.sh
&rootprompt; /etc/samba # ./initGrps.sh
Updated mapping entry for Domain Admins
Updated mapping entry for Domain Users
Updated mapping entry for Domain Guests
No rid or sid specified, choosing algorithmic mapping
Successfully added group Accounts Dept to the mapping db
No rid or sid specified, choosing algorithmic mapping
Successfully added group Domain Guests to the mapping db
&rootprompt; /etc/samba # net groupmap list | sort
Account Operators (S-1-5-32-548) -> -1
Accounts Dept (S-1-5-21-179504-2437109-488451-2003) -> acctsdep
Administrators (S-1-5-32-544) -> -1
Backup Operators (S-1-5-32-551) -> -1
Domain Admins (S-1-5-21-179504-2437109-488451-512) -> root
Domain Guests (S-1-5-21-179504-2437109-488451-514) -> nobody
Domain Users (S-1-5-21-179504-2437109-488451-513) -> users
Financial Services (S-1-5-21-179504-2437109-488451-2005) -> finsrvcs
Guests (S-1-5-32-546) -> -1
Power Users (S-1-5-32-547) -> -1
Print Operators (S-1-5-32-550) -> -1
Replicators (S-1-5-32-552) -> -1
System Operators (S-1-5-32-549) -> -1
Users (S-1-5-32-545) -> -1
</screen>
</para></step>
<step><para>
<indexterm><primary>useradd</primary></indexterm>
<indexterm><primary>adduser</primary></indexterm>
<indexterm><primary>passwd</primary></indexterm>
<indexterm><primary>smbpasswd</primary></indexterm>
<indexterm><primary>/etc/passwd</primary></indexterm>
<indexterm><primary>password</primary><secondary>backend</secondary></indexterm>
<indexterm><primary>user</primary><secondary>management</secondary></indexterm>
There is one preparatory step without which you will not have a working Samba
network environment. You must add an account for each network user.
For each user who needs to be given a Windows Domain account, make an entry in the
<filename>/etc/passwd</filename> file as well as in the Samba password backend.
Use the system tool of your choice to create the UNIX system account, and use the Samba
<command>smbpasswd</command> to create a Domain user account.
There are a number of tools for user management under UNIX, such as
<command>useradd</command>, and <command>adduser</command>, as well as a plethora of custom
tools. You also want to create a home directory for each user.
You can do this by executing the following steps for each user:
<screen>
&rootprompt; useradd -m <parameter>username</parameter>
&rootprompt; passwd <parameter>username</parameter>
Changing password for <parameter>username</parameter>.
New password: XXXXXXXX
Re-enter new password: XXXXXXXX
Password changed
&rootprompt; smbpasswd -a <parameter>username</parameter>
New SMB password: XXXXXXXX
Retype new SMB password: XXXXXXXX
Added user <parameter>username</parameter>.
</screen>
You do of course use a valid user login ID in place of <parameter>username</parameter>.
</para></step>
<step><para>
<indexterm><primary>file system</primary><secondary>access control</secondary></indexterm>
<indexterm><primary>file system</primary><secondary>permissions</secondary></indexterm>
<indexterm><primary>group membership</primary></indexterm>
Using the preferred tool for your UNIX system, add each user to the UNIX groups created
previously as necessary. File system access control will be based on UNIX group membership.
</para></step>
<step><para>
Create the directory mount point for the disk subsystem that can be mounted to provide
data storage for company files. In this case the mount point is indicated in the &smb.conf;
file is <filename>/data</filename>. Format the file system as required, and mount the formatted
file system partition using appropriate system tools.
</para></step>
<step><para>
<indexterm><primary>file system</primary><secondary>permissions</secondary></indexterm>
Create the top-level file storage directories for data and applications as follows:
<screen>
&rootprompt; mkdir -p /data/{accounts,finsrvcs}
&rootprompt; mkdir -p /apps
&rootprompt; chown -R root:root /data
&rootprompt; chown -R root:root /apps
&rootprompt; chown -R bjordan:acctsdep /data/accounts
&rootprompt; chown -R bjordan:finsrvcs /data/finsrvcs
&rootprompt; chmod -R ug+rwxs,o-rwx /data
&rootprompt; chmod -R ug+rwx,o+rx-w /apps
</screen>
Each department is responsible for creating its own directory structure within the departmental
share. The directory root of the <command>accounts</command> share is <filename>/data/accounts</filename>.
The directory root of the <command>finsvcs</command> share is <filename>/data/finsvcs</filename>.
The <filename>/apps</filename> directory is the root of the <constant>apps</constant> share
that provides the application server infrastructure.
</para></step>
<step><para>
The &smb.conf; file specifies an infrastructure to support roaming profiles and network
logon services. You can now create the file system infrastructure to provide the
locations on disk that these services require. Adequate planning is essential,
since desktop profiles can grow to be quite large. For planning purposes, a minimum of
200 MB of storage should be allowed per user for profile storage. The following
commands create the directory infrastructure needed:
<screen>
&rootprompt; mkdir -p /var/spool/samba
&rootprompt; mkdir -p /var/lib/samba/{netlogon/scripts,profiles}
&rootprompt; chown -R root:root /var/spool/samba
&rootprompt; chown -R root:root /var/lib/samba
&rootprompt; chmod a+rwxt /var/spool/samba
&rootprompt; chmod 2775 /var/lib/samba/profiles
&rootprompt; chgrp users /var/lib/samba/profiles
</screen>
For each user account that is created on the system, the following commands should be
executed:
<screen>
&rootprompt; mkdir /var/lib/samba/profiles/'username'
&rootprompt; chown 'username':users /var/lib/samba/profiles/'username'
&rootprompt; chmod ug+wrx,o+rx,-w /var/lib/samba/profiles/'username'
</screen>
</para></step>
<step><para>
<indexterm><primary>logon scrip</primary></indexterm>
<indexterm><primary>unix2dos</primary></indexterm>
<indexterm><primary>dos2unix</primary></indexterm>
Create a logon script. It is important that each line is correctly terminated with
a carriage return and line-feed combination (i.e., DOS encoding). The following procedure
works if the right tools (<constant>unix2dos</constant> and <constant>dos2unix</constant>) are installed.
First, create a file called <filename>/var/lib/samba/netlogon/scripts/logon.bat.unix</filename>
with the following contents:
<screen>
net time \\diamond /set /yes
net use h: /home
net use p: \\diamond\apps
</screen>
Convert the UNIX file to a DOS file using the <command>unix2dos</command> as shown here:
<screen>
&rootprompt; unix2dos &lt; /var/lib/samba/netlogon/scripts/logon.bat.unix \
&gt; /var/lib/samba/netlogon/scripts/logon.bat
</screen>
</para></step>
</procedure>
</sect2>
<sect2 id="ch4dhcpdns">
<title>Configuration of DHCP and DNS Servers</title>
<para>
DHCP services are a basic component of the entire network client installation. DNS operation is
foundational to Internet access as well as to trouble-free operation of local networking. When
you have completed this section, the server should be ready for solid duty operation.
</para>
<procedure>
<title>DHCP and DNS Server Configuration Steps</title>
<step><para>
<indexterm><primary>/etc/dhcpd.conf</primary></indexterm>
Create a file called <filename>/etc/dhcpd.conf</filename> with the contents as
shown in <link linkend="prom-dhcp"/>.
<example id="prom-dhcp">
<title>DHCP Server Configuration File &smbmdash; <filename>/etc/dhcpd.conf</filename></title>
<screen>
# Abmas Accounting Inc.
default-lease-time 86400;
max-lease-time 172800;
default-lease-time 86400;
option ntp-servers 192.168.1.1;
option domain-name "abmas.biz";
option domain-name-servers 192.168.1.1, 192.168.2.1;
option netbios-name-servers 192.168.1.1, 192.168.2.1;
option netbios-node-type 8; ### Node type = Hybrid ###
ddns-updates on; ### Dynamic DNS enabled ###
ddns-update-style interim;
subnet 192.168.1.0 netmask 255.255.255.0 {
range dynamic-bootp 192.168.1.128 192.168.1.254;
option subnet-mask 255.255.255.0;
option routers 192.168.1.1;
allow unknown-clients;
host qmsa {
hardware ethernet 08:00:46:7a:35:e4;
fixed-address 192.168.1.20;
}
host hplj6a {
hardware ethernet 00:03:47:cb:81:e0;
fixed-address 192.168.1.30;
}
}
subnet 192.168.2.0 netmask 255.255.255.0 {
range dynamic-bootp 192.168.2.128 192.168.2.254;
option subnet-mask 255.255.255.0;
option routers 192.168.2.1;
allow unknown-clients;
host qmsf {
hardware ethernet 01:04:31:db:e1:c0;
fixed-address 192.168.1.20;
}
host hplj6f {
hardware ethernet 00:03:47:cf:83:e2;
fixed-address 192.168.2.30;
}
}
subnet 127.0.0.0 netmask 255.0.0.0 {
}
subnet 123.45.67.64 netmask 255.255.255.252 {
}
</screen>
</example>
</para></step>
<step><para>
<indexterm><primary>/etc/named.conf</primary></indexterm>
Create a file called <filename>/etc/named.conf</filename> that has the combined contents
of the <link linkend="ch4namedcfg"/>, <link linkend="ch4namedvarfwd"/>, and
<link linkend="ch4namedvarrev"/> files that are concatenated (merged) in this
specific order.
</para></step>
<step><para>
Create the files shown in their respective directories as shown in <link linkend="namedrscfiles">DNS
(named) Resource Files</link>.
<table id="namedrscfiles">
<title>DNS (named) Resource Files</title>
<tgroup cols="2">
<colspec align="left"/>
<colspec align="left"/>
<thead>
<row>
<entry>Reference</entry>
<entry>File Location</entry>
</row>
</thead>
<tbody>
<row>
<entry><link linkend="loopback"/></entry>
<entry>/var/lib/named/localhost.zone</entry>
</row>
<row>
<entry><link linkend="dnsloopy"/></entry>
<entry>/var/lib/named/127.0.0.zone</entry>
</row>
<row>
<entry><link linkend="roothint"/></entry>
<entry>/var/lib/named/root.hint</entry>
</row>
<row>
<entry><link linkend="abmasbiz"/></entry>
<entry>/var/lib/named/master/abmas.biz.hosts</entry>
</row>
<row>
<entry><link linkend="abmasus"/></entry>
<entry>/var/lib/named/abmas.us.hosts</entry>
</row>
<row>
<entry><link linkend="eth1zone"/></entry>
<entry>/var/lib/named/192.168.1.0.rev</entry>
</row>
<row>
<entry><link linkend="eth2zone"/></entry>
<entry>/var/lib/named/192.168.2.0.rev</entry>
</row>
</tbody>
</tgroup>
</table>
<example id="ch4namedcfg">
<title>DNS Master Configuration File &smbmdash; <filename>/etc/named.conf</filename> Master Section</title>
<indexterm><primary>/etc/named.conf</primary></indexterm>
<screen>
###
# Abmas Biz DNS Control File
###
# Date: November 15, 2003
###
options {
directory "/var/lib/named";
forwarders {
123.45.12.23;
};
forward first;
listen-on {
mynet;
};
auth-nxdomain yes;
multiple-cnames yes;
notify no;
};
zone "." in {
type hint;
file "root.hint";
};
zone "localhost" in {
type master;
file "localhost.zone";
};
zone "0.0.127.in-addr.arpa" in {
type master;
file "127.0.0.zone";
};
acl mynet {
192.168.1.0/24;
192.168.2.0/24;
127.0.0.1;
};
acl seconddns {
123.45.54.32;
};
</screen>
</example>
<example id="ch4namedvarfwd">
<title>DNS Master Configuration File &smbmdash; <filename>/etc/named.conf</filename> Forward Lookup Definition Section</title>
<screen>
zone "abmas.biz" {
type master;
file "/var/lib/named/master/abmas.biz.hosts";
allow-query {
mynet;
};
allow-transfer {
mynet;
};
allow-update {
mynet;
};
};
zone "abmas.us" {
type master;
file "/var/lib/named/master/abmas.us.hosts";
allow-query {
any;
};
allow-transfer {
seconddns;
};
};
</screen>
</example>
<example id="ch4namedvarrev">
<title>DNS Master Configuration File &smbmdash; <filename>/etc/named.conf</filename> Reverse Lookup Definition Section</title>
<screen>
zone "1.168.192.in-addr.arpa" {
type master;
file "/var/lib/named/master/192.168.1.0.rev";
allow-query {
mynet;
};
allow-transfer {
mynet;
};
allow-update {
mynet;
};
};
zone "2.168.192.in-addr.arpa" {
type master;
file "/var/lib/named/master/192.168.2.0.rev";
allow-query {
mynet;
};
allow-transfer {
mynet;
};
allow-update {
mynet;
};
};
</screen>
</example>
<example id="eth1zone">
<title>DNS 192.168.1 Reverse Zone File</title>
<screen>
$ORIGIN .
$TTL 38400 ; 10 hours 40 minutes
1.168.192.in-addr.arpa IN SOA sleeth.abmas.biz. root.abmas.biz. (
2003021825 ; serial
10800 ; refresh (3 hours)
3600 ; retry (1 hour)
604800 ; expire (1 week)
38400 ; minimum (10 hours 40 minutes)
)
NS sleeth1.abmas.biz.
$ORIGIN 1.168.192.in-addr.arpa.
1 PTR sleeth1.abmas.biz.
20 PTR qmsa.abmas.biz.
30 PTR hplj6a.abmas.biz.
</screen>
</example>
<example id="eth2zone">
<title>DNS 192.168.2 Reverse Zone File</title>
<screen>
$ORIGIN .
$TTL 38400 ; 10 hours 40 minutes
2.168.192.in-addr.arpa IN SOA sleeth.abmas.biz. root.abmas.biz. (
2003021825 ; serial
10800 ; refresh (3 hours)
3600 ; retry (1 hour)
604800 ; expire (1 week)
38400 ; minimum (10 hours 40 minutes)
)
NS sleeth2.abmas.biz.
$ORIGIN 2.168.192.in-addr.arpa.
1 PTR sleeth2.abmas.biz.
20 PTR qmsf.abmas.biz.
30 PTR hplj6f.abmas.biz.
</screen>
</example>
<example id="abmasbiz">
<title>DNS Abmas.biz Forward Zone File</title>
<screen>
$ORIGIN .
$TTL 38400 ; 10 hours 40 minutes
abmas.biz IN SOA sleeth1.abmas.biz. root.abmas.biz. (
2003021833 ; serial
10800 ; refresh (3 hours)
3600 ; retry (1 hour)
604800 ; expire (1 week)
38400 ; minimum (10 hours 40 minutes)
)
NS dns.abmas.biz.
MX 10 mail.abmas.biz.
$ORIGIN abmas.biz.
sleeth1 A 192.168.1.1
sleeth2 A 192.168.2.1
qmsa A 192.168.1.20
hplj6a A 192.168.1.30
qmsf A 192.168.2.20
hplj6f A 192.168.2.30
dns CNAME sleeth1
diamond CNAME sleeth1
mail CNAME sleeth1
</screen>
</example>
<example id="abmasus">
<title>DNS Abmas.us Forward Zone File</title>
<screen>
$ORIGIN .
$TTL 38400 ; 10 hours 40 minutes
abmas.us IN SOA server.abmas.us. root.abmas.us. (
2003021833 ; serial
10800 ; refresh (3 hours)
3600 ; retry (1 hour)
604800 ; expire (1 week)
38400 ; minimum (10 hours 40 minutes)
)
NS dns.abmas.us.
NS dns2.abmas.us.
MX 10 mail.abmas.us.
$ORIGIN abmas.us.
server A 123.45.67.66
dns2 A 123.45.54.32
gw A 123.45.67.65
www CNAME server
mail CNAME server
dns CNAME server
</screen>
</example>
</para></step>
<step><para>
<indexterm><primary>/etc/resolv.conf</primary></indexterm><indexterm>
<primary>name resolution</primary>
</indexterm>
All DNS name resolution should be handled locally. To ensure that the server is configured
correctly to handle this, edit <filename>/etc/resolv.conf</filename> to have the following
content:
<screen>
search abmas.us abmas.biz
nameserver 127.0.0.1
nameserver 123.45.54.23
</screen>
<indexterm>
<primary>DNS server</primary>
</indexterm>
This instructs the name resolver function (when configured correctly) to ask the DNS server
that is running locally to resolve names to addresses. In the event that the local name server
is not available, ask the name server provided by the ISP. The latter, of course, does not resolve
purely local names to IP addresses.
</para></step>
<step><para>
<indexterm><primary>/etc/nsswitch.conf</primary></indexterm>
The final step is to edit the <filename>/etc/nsswitch.conf</filename> file.
This file controls the operation of the various resolver libraries that are part of the Linux
Glibc libraries. Edit this file so that it contains the following entries:
<screen>
hosts: files dns wins
</screen>
</para></step>
</procedure>
<para>
The basic DHCP and DNS services are now ready for validation testing. Before you can proceed,
there are a few more steps along the road. First, configure the print spooling and print
processing system. Then you can configure the server so that all services
start automatically on reboot. You must also manually start all services prior to validation testing.
</para>
</sect2>
<sect2 id="ch4ptrcfg">
<title>Printer Configuration</title>
<para>
Network administrators who are new to CUPS based-printing typically experience some difficulty mastering
its powerful features. The steps outlined in this section are designed to navigate around the distractions
of learning CUPS. Instead of implementing smart features and capabilities, our approach is to use it as a
transparent print queue that performs no filtering, and only minimal handling of each print job that is
submitted to it. In other words, our configuration turns CUPS into a raw-mode print queue. This means that
the correct printer driver must be installed on all clients.
</para>
<procedure>
<title>Printer Configuration Steps</title>
<step><para>
Configure each printer to be a DHCP client, carefully following the manufacturer's guidelines.
</para></step>
<step><para>
Follow the instructions in the printer manufacturer's manuals to permit printing to port 9100.
Use any other port the manufacturer specifies for direct-mode raw printing, and adjust the
port as necessary in the following example commands.
This allows the CUPS spooler to print using raw mode protocols.
<indexterm><primary>CUPS</primary></indexterm>
<indexterm><primary>raw printing</primary></indexterm>
</para></step>
<step><para>
<indexterm><primary>CUPS</primary><secondary>queue</secondary></indexterm><indexterm>
<primary>lpadmin</primary>
</indexterm>
Configure the CUPS Print Queues as follows:
<screen>
&rootprompt; lpadmin -p qmsa -v socket://qmsa.abmas.biz:9100 -E
&rootprompt; lpadmin -p hplj6a -v socket://hplj6a.abmas.biz:9100 -E
&rootprompt; lpadmin -p qmsf -v socket://qmsf.abmas.biz:9100 -E
&rootprompt; lpadmin -p hplj6f -v socket://hplj6f.abmas.biz:9100 -E
</screen>
<indexterm><primary>print filter</primary></indexterm>
This creates the necessary print queues with no assigned print filter.
</para></step>
<step><para><indexterm>
<primary>enable</primary>
</indexterm>
Print queues may not be enabled at creation. Use <command>lpc stat</command> to check
the status of the print queues and, if necessary, make certain that the queues you have
just created are enabled by executing the following:
<screen>
&rootprompt; /usr/bin/enable qmsa
&rootprompt; /usr/bin/enable hplj6a
&rootprompt; /usr/bin/enable qmsf
&rootprompt; /usr/bin/enable hplj6f
</screen>
</para></step>
<step><para><indexterm>
<primary>accept</primary>
</indexterm>
Even though your print queues may be enabled, it is still possible that they
are not accepting print jobs. A print queue services incoming printing
requests only when configured to do so. Ensure that your print queues are
set to accept incoming jobs by executing the following commands:
<screen>
&rootprompt; /usr/sbin/accept qmsa
&rootprompt; /usr/sbin/accept hplj6a
&rootprompt; /usr/sbin/accept qmsf
&rootprompt; /usr/sbin/accept hplj6f
</screen>
</para></step>
<step><para>
<indexterm><primary>mime type</primary></indexterm>
<indexterm><primary>/etc/mime.convs</primary></indexterm>
<indexterm><primary>application/octet-stream</primary></indexterm>
Edit the file <filename>/etc/cups/mime.convs</filename> to uncomment the line:
<screen>
application/octet-stream application/vnd.cups-raw 0 -
</screen>
</para></step>
<step><para>
<indexterm><primary>/etc/mime.types</primary></indexterm>
Edit the file <filename>/etc/cups/mime.types</filename> to uncomment the line:
<screen>
application/octet-stream
</screen>
</para></step>
<step><para>
Printing drivers are installed on each network client workstation.
</para></step>
</procedure>
<para>
Note: If the parameter <parameter>cups options = Raw</parameter> is specified in the &smb.conf; file,
the last two steps can be omitted with CUPS version 1.1.18, or later.
</para>
<para>
The UNIX system print queues have been configured and are ready for validation testing.
</para>
</sect2>
<sect2 id="procstart">
<title>Process Startup Configuration</title>
<para>
<indexterm><primary>chkconfig</primary></indexterm>
There are two essential steps to process startup configuration. First, the process
must be configured so that it automatically restarts each time the server
is rebooted. This step involves use of the <command>chkconfig</command> tool that
creates the appropriate symbolic links from the master daemon control file that is
located in the <filename>/etc/rc.d</filename> directory, to the <filename>/etc/rc'x'.d</filename>
directories. Links are created so that when the system run level is changed, the
necessary start or kill script is run.
</para>
<para>
<indexterm><primary>/etc/xinetd.d</primary></indexterm>
<indexterm><primary>inetd</primary></indexterm>
<indexterm><primary>xinetd</primary></indexterm>
<indexterm><primary>chkconfig</primary></indexterm>
<indexterm><primary>super daemon</primary></indexterm>
In the event that a service is not run as a daemon, but via the internetworking
super daemon (<command>inetd</command> or <command>xinetd</command>), then the <command>chkconfig</command>
tool makes the necessary entries in the <filename>/etc/xinetd.d</filename> directory
and sends a hang-up (HUP) signal to the the super daemon, thus forcing it to
re-read its control files.
</para>
<para>
Last, each service must be started to permit system validation to proceed.
</para>
<procedure>
<step><para>
Use the standard system tool to configure each service to restart
automatically at every system reboot. For example,
<indexterm><primary>chkconfig</primary></indexterm>
<screen>
&rootprompt; chkconfig dhpcd on
&rootprompt; chkconfig named on
&rootprompt; chkconfig cups on
&rootprompt; chkconfig smb on
</screen>
</para></step>
<step><para>
<indexterm><primary>starting dhcpd</primary></indexterm>
<indexterm><primary>starting samba</primary></indexterm>
<indexterm><primary>starting CUPS</primary></indexterm>
Now start each service to permit the system to be validated.
Execute each of the following in the sequence shown:
<screen>
&rootprompt; /etc/rc.d/init.d/dhcpd restart
&rootprompt; /etc/rc.d/init.d/named restart
&rootprompt; /etc/rc.d/init.d/cups restart
&rootprompt; /etc/rc.d/init.d/smb restart
</screen>
</para></step>
</procedure>
</sect2>
<sect2 id="ch4valid">
<title>Validation</title>
<para>
<indexterm><primary>validation</primary></indexterm>
Complex networking problems are most often caused by simple things that are poorly or incorrectly
configured. The validation process adopted here should be followed carefully; it is the result of the
experience gained from years of making and correcting the most common mistakes. Shortcuts often lead to basic errors. You should
refrain from taking shortcuts, from making basic assumptions, and from not exercising due process
and diligence in network validation. By thoroughly testing and validating every step in the process
of network installation and configuration, you can save yourself from sleepless nights and restless
days. A well debugged network is a foundation for happy network users and network administrators.
Later in this book you learn how to make users happier. For now, it is enough to learn to
validate. Let's get on with it.
</para>
<procedure>
<title>Server Validation Steps</title>
<step><para>
<indexterm><primary>/etc/nsswitch.conf</primary></indexterm>
One of the most important facets of Samba configuration is to ensure that
name resolution functions correctly. You can check name resolution
with a few simple tests. The most basic name resolution is provided from the
<filename>/etc/hosts</filename> file. To test its operation, make a
temporary edit to the <filename>/etc/nsswitch.conf</filename> file. Using
your favorite editor, change the entry for <constant>hosts</constant> to read:
<screen>
hosts: files
</screen>
When you have saved this file, execute the following command:
<screen>
&rootprompt; ping diamond
PING sleeth1.abmas.biz (192.168.1.1) 56(84) bytes of data.
64 bytes from sleeth1 (192.168.1.1): icmp_seq=1 ttl=64 time=0.131 ms
64 bytes from sleeth1 (192.168.1.1): icmp_seq=2 ttl=64 time=0.179 ms
64 bytes from sleeth1 (192.168.1.1): icmp_seq=3 ttl=64 time=0.192 ms
64 bytes from sleeth1 (192.168.1.1): icmp_seq=4 ttl=64 time=0.191 ms
--- sleeth1.abmas.biz ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3016ms
rtt min/avg/max/mdev = 0.131/0.173/0.192/0.026 ms
</screen>
This proves that name resolution via the <filename>/etc/hosts</filename> file
is working.
</para></step>
<step><para>
<indexterm><primary>/etc/nsswitch.conf</primary></indexterm>
So far, your installation is going particularly well. In this step we validate
DNS server and name resolution operation. Using your favorite UNIX system editor,
change the <filename>/etc/nsswitch.conf</filename> file so that the
<constant>hosts</constant> entry reads:
<screen>
hosts: dns
</screen>
</para></step>
<step><para>
<indexterm><primary>named</primary></indexterm>
Before you test DNS operation, it is a good idea to verify that the DNS server
is running by executing the following:
<screen>
&rootprompt; ps ax | grep named
437 ? S 0:00 /sbin/syslogd -a /var/lib/named/dev/log
524 ? S 0:00 /usr/sbin/named -t /var/lib/named -u named
525 ? S 0:00 /usr/sbin/named -t /var/lib/named -u named
526 ? S 0:00 /usr/sbin/named -t /var/lib/named -u named
529 ? S 0:00 /usr/sbin/named -t /var/lib/named -u named
540 ? S 0:00 /usr/sbin/named -t /var/lib/named -u named
2552 pts/2 S 0:00 grep named
</screen>
This means that we are ready to check DNS operation. Do so by executing:
<indexterm><primary>ping</primary></indexterm>
<screen>
&rootprompt; ping diamond
PING sleeth1.abmas.biz (192.168.1.1) 56(84) bytes of data.
64 bytes from sleeth1 (192.168.1.1): icmp_seq=1 ttl=64 time=0.156 ms
64 bytes from sleeth1 (192.168.1.1): icmp_seq=2 ttl=64 time=0.183 ms
--- sleeth1.abmas.biz ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 999ms
rtt min/avg/max/mdev = 0.156/0.169/0.183/0.018 ms
</screen>
You should take a few more steps to validate DNS server operation, as follows:
<screen>
&rootprompt; host -f diamond.abmas.biz
sleeth1.abmas.biz has address 192.168.1.1
</screen>
<indexterm><primary>/etc/hosts</primary></indexterm>
You may now remove the entry called <constant>diamond</constant> from the
<filename>/etc/hosts</filename> file. It does not hurt to leave it there,
but its removal reduces the number of administrative steps for this name.
</para></step>
<step><para>
<indexterm><primary>/etc/nsswitch.conf</primary></indexterm>
WINS is a great way to resolve NetBIOS names to their IP address. You can test
the operation of WINS by starting <command>nmbd</command> (manually or by way
of the Samba startup method shown in <link linkend="procstart"/>). You must edit
the <filename>/etc/nsswitch.conf</filename> file so that the <constant>hosts</constant>
entry is as follows:
<screen>
hosts: wins
</screen>
The next step is to make certain that Samba is running using <command>ps ax | grep mbd</command>.
The <command>nmbd</command> daemon will provide the WINS name resolution service when the
&smb.conf; file <smbconfsection name="global"/> parameter <smbconfoption name="wins
support">Yes</smbconfoption> has been specified. Having validated that Samba is operational,
excute the following:
<screen>
&rootprompt; ping diamond
PING diamond (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.094 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.479 ms
</screen>
<indexterm><primary>ping</primary></indexterm>
Now that you can relax with the knowledge that all three major forms of name
resolution to IP address resolution are working, edit the <filename>/etc/nsswitch.conf</filename>
again. This time you add all three forms of name resolution to this file.
Your edited entry for <constant>hosts</constant> should now look like this:
<screen>
hosts: files dns wins
</screen>
The system is looking good. Let's move on.
</para></step>
<step><para>
It would give you peace of mind to know that the DHCP server is running
and available for service. You can validate DHCP services by running:
<screen>
&rootprompt; ps ax | grep dhcp
2618 ? S 0:00 /usr/sbin/dhcpd ...
8180 pts/2 S 0:00 grep dhcp
</screen>
This shows that the server is running. The proof of whether or not it is working
comes when you try to add the first DHCP client to the network.
</para></step>
<step><para>
<indexterm><primary>testparm</primary></indexterm>
This is a good point at which to start validating Samba operation. You are
content that name resolution is working for basic TCP/IP needs. Let's move on.
If your &smb.conf; file has bogus options or parameters, this may cause Samba
to refuse to start. The first step should always be to validate the contents
of this file by running:
<screen>
&rootprompt; testparm -s
Load smb config files from smb.conf
Processing section "[homes]"
Processing section "[printers]"
Processing section "[netlogon]"
Processing section "[profiles]"
Processing section "[accounts]"
Processing section "[service]"
Processing section "[apps]"
Loaded services file OK.
# Global parameters
[global]
workgroup = PROMISES
netbios name = DIAMOND
interfaces = eth1, eth2, lo
bind interfaces only = Yes
passdb backend = tdbsam
pam password change = Yes
passwd program = /usr/bin/passwd '%u'
passwd chat = *New*Password* %n\n \
*Re-enter*new*password* %n\n *Password*changed*
username map = /etc/samba/smbusers
unix password sync = Yes
log level = 1
syslog = 0
log file = /var/log/samba/%m
max log size = 50
smb ports = 139
name resolve order = wins bcast hosts
time server = Yes
printcap name = CUPS
show add printer wizard = No
add user script = /usr/sbin/useradd -m '%u'
delete user script = /usr/sbin/userdel -r '%u'
add group script = /usr/sbin/groupadd '%g'
delete group script = /usr/sbin/groupdel '%g'
add user to group script = /usr/sbin/usermod -G '%g' '%u'
add machine script = /usr/sbin/useradd \
-s /bin/false -d /dev/null '%u'
shutdown script = /var/lib/samba/scripts/shutdown.sh
abort shutdown script = /sbin/shutdown -c
logon script = scripts\logon.bat
logon path = \\%L\profiles\%U
logon drive = X:
logon home = \\%L\%U
domain logons = Yes
preferred master = Yes
wins support = Yes
utmp = Yes
winbind use default domain = Yes
map acl inherit = Yes
cups options = Raw
veto files = /*.eml/*.nws/*.{*}/
veto oplock files = /*.doc/*.xls/*.mdb/
[homes]
comment = Home Directories
valid users = %S
read only = No
browseable = No
...
### Remainder cut to save space ###
</screen>
Clear away all errors before proceeding.
</para></step>
<step><para>
<indexterm><primary>check samba daemons</primary></indexterm>
<indexterm><primary>smbd</primary></indexterm>
<indexterm><primary>nmbd</primary></indexterm>
<indexterm><primary>winbindd</primary></indexterm>
Check that the Samba server is running:
<screen>
&rootprompt; ps ax | grep mbd
14244 ? S 0:00 /usr/sbin/nmbd -D
14245 ? S 0:00 /usr/sbin/nmbd -D
14290 ? S 0:00 /usr/sbin/smbd -D
$rootprompt; ps ax | grep winbind
14293 ? S 0:00 /usr/sbin/winbindd -D
14295 ? S 0:00 /usr/sbin/winbindd -D
</screen>
The <command>winbindd</command> daemon is running in split mode (normal), so there are also
two instances<footnote><para>For more information regarding winbindd, see <emphasis>TOSHARG2</emphasis>,
Chapter 23, Section 23.3. The single instance of <command>smbd</command> is normal. One additional
<command>smbd</command> slave process is spawned for each SMB/CIFS client
connection.</para></footnote> of it.
</para></step>
<step><para>
<indexterm><primary>anonymous
connection</primary></indexterm>
<indexterm>
<primary>smbclient</primary>
</indexterm>
Check that an anonymous connection can be made to the Samba server:
<screen>
&rootprompt; smbclient -L localhost -U%
Sharename Type Comment
--------- ---- -------
IPC$ IPC IPC Service (Samba 3.0.20)
netlogon Disk Network Logon Service
profiles Disk Profile Share
accounts Disk Accounting Files
service Disk Financial Services Files
apps Disk Application Files
ADMIN$ IPC IPC Service (Samba 3.0.20)
hplj6a Printer hplj6a
hplj6f Printer hplj6f
qmsa Printer qmsa
qmsf Printer qmsf
Server Comment
--------- -------
DIAMOND Samba 3.0.20
Workgroup Master
--------- -------
PROMISES DIAMOND
</screen>
This demonstrates that an anonymous listing of shares can be obtained. This is the equivalent
of browsing the server from a Windows client to obtain a list of shares on the server.
The <constant>-U%</constant> argument means to send a <constant>NULL</constant> username and
a <constant>NULL</constant> password.
</para></step>
<step><para>
<indexterm><primary>dhcp client validation</primary></indexterm>
<indexterm><primary>printer validation</primary></indexterm>
<indexterm><primary>arp</primary></indexterm>
Verify that each printer has the IP address assigned in the DHCP server configuration file.
The easiest way to do this is to ping the printer name. Immediately after the ping response
has been received, execute <command>arp -a</command> to find the MAC address of the printer
that has responded. Now you can compare the IP address and the MAC address of the printer
with the configuration information in the <filename>/etc/dhcpd.conf</filename> file. They
should, of course, match. For example,
<screen>
&rootprompt; ping hplj6
PING hplj6a (192.168.1.30) 56(84) bytes of data.
64 bytes from hplj6a (192.168.1.30): icmp_seq=1 ttl=64 time=0.113 ms
&rootprompt; arp -a
hplj6a (192.168.1.30) at 00:03:47:CB:81:E0 [ether] on eth0
</screen>
<indexterm>
<primary>/etc/dhcpd.conf</primary>
</indexterm>
The MAC address <constant>00:03:47:CB:81:E0</constant> matches that specified for the
IP address from which the printer has responded and with the entry for it in the
<filename>/etc/dhcpd.conf</filename> file. Repeat this for each printer configured.
</para></step>
<step><para>
<indexterm><primary>authenticated connection</primary></indexterm>
Make an authenticated connection to the server using the <command>smbclient</command> tool:
<screen>
&rootprompt; smbclient //diamond/accounts -U gholmes
Password: XXXXXXX
smb: \> dir
. D 0 Thu Nov 27 15:07:09 2003
.. D 0 Sat Nov 15 17:40:50 2003
zakadmin.exe 161424 Thu Nov 27 15:06:52 2003
zak.exe 6066384 Thu Nov 27 15:06:52 2003
dhcpd.conf 1256 Thu Nov 27 15:06:52 2003
smb.conf 2131 Thu Nov 27 15:06:52 2003
initGrps.sh A 1089 Thu Nov 27 15:06:52 2003
POLICY.EXE 86542 Thu Nov 27 15:06:52 2003
55974 blocks of size 65536. 33968 blocks available
smb: \> q
</screen>
</para></step>
<step><para>
<indexterm><primary>nmap</primary></indexterm>
Your new server is connected to an Internet-accessible connection. Before you start
your firewall, you should run a port scanner against your system. You should repeat that
after the firewall has been started. This helps you understand to what extent the
server may be vulnerable to external attack. One way you can do this is by using an
external service, such as the <ulink url="http://www.dslreports.com/scan">DSL Reports</ulink>
tools. Alternately, if you can gain root-level access to a remote
UNIX/Linux system that has the <command>nmap</command> tool, you can run the following:
<screen>
&rootprompt; nmap -v -sT server.abmas.us
Starting nmap V. 3.00 ( www.insecure.org/nmap/ )
Host server.abmas.us (123.45.67.66) appears to be up ... good.
Initiating Connect() Scan against server.abmas.us (123.45.67.66)
Adding open port 6000/tcp
Adding open port 873/tcp
Adding open port 445/tcp
Adding open port 10000/tcp
Adding open port 901/tcp
Adding open port 631/tcp
Adding open port 25/tcp
Adding open port 111/tcp
Adding open port 32770/tcp
Adding open port 3128/tcp
Adding open port 53/tcp
Adding open port 80/tcp
Adding open port 443/tcp
Adding open port 139/tcp
Adding open port 22/tcp
The Connect() Scan took 0 seconds to scan 1601 ports.
Interesting ports on server.abmas.us (123.45.67.66):
(The 1587 ports scanned but not shown below are in state: closed)
Port State Service
22/tcp open ssh
25/tcp open smtp
53/tcp open domain
80/tcp open http
111/tcp open sunrpc
139/tcp open netbios-ssn
443/tcp open https
445/tcp open microsoft-ds
631/tcp open ipp
873/tcp open rsync
901/tcp open samba-swat
3128/tcp open squid-http
6000/tcp open X11
10000/tcp open snet-sensor-mgmt
32770/tcp open sometimes-rpc3
Nmap run completed -- 1 IP address (1 host up) scanned in 1 second
</screen>
The above scan was run before the external interface was locked down with the NAT-firewall
script you created above. The following results are obtained after the firewall rules
have been put into place:
<screen>
&rootprompt; nmap -v -sT server.abmas.us
Starting nmap V. 3.00 ( www.insecure.org/nmap/ )
Host server.abmas.us (123.45.67.66) appears to be up ... good.
Initiating Connect() Scan against server.abmas.us (123.45.67.66)
Adding open port 53/tcp
Adding open port 22/tcp
The Connect() Scan took 168 seconds to scan 1601 ports.
Interesting ports on server.abmas.us (123.45.67.66):
(The 1593 ports scanned but not shown below are in state: filtered)
Port State Service
22/tcp open ssh
25/tcp closed smtp
53/tcp open domain
80/tcp closed http
443/tcp closed https
Nmap run completed -- 1 IP address (1 host up) scanned in 168 seconds
</screen>
</para></step>
</procedure>
</sect2>
<sect2 id="ch4appscfg">
<title>Application Share Configuration</title>
<para>
<indexterm><primary>application server</primary></indexterm>
<indexterm><primary>administrative installation</primary></indexterm>
The use of an application server is a key mechanism by which desktop administration overheads
can be reduced. Check the application manual for your software to identify how best to
create an administrative installation.
</para>
<para>
Some Windows software will only run locally on the desktop computer. Such software
is typically not suited for administrative installation. Administratively installed software
permits one or more of the following installation choices:
</para>
<itemizedlist>
<listitem><para>
Install software fully onto a workstation, storing data files on the same workstation.
</para></listitem>
<listitem><para>
Install software fully onto a workstation with central network data file storage.
</para></listitem>
<listitem><para>
Install software to run off a central application server with data files stored
on the local workstation. This is often called a minimum installation, or a
network client installation.
</para></listitem>
<listitem><para>
Install software to run off a central application server with data files stored
on a central network share. This type of installation often prevents storage
of work files on the local workstation.
</para></listitem>
</itemizedlist>
<para>
<indexterm><primary></primary></indexterm>
A common application deployed in this environment is an office suite.
Enterprise editions of Microsoft Office XP Professional can be administratively installed
by launching the installation from a command shell. The command that achieves this is
<command>setup /a</command>. It results in a set of prompts through which various
installation choices can be made. Refer to the Microsoft Office Resource SDK and Resource
Kit for more information regarding this mode of installation of MS Office XP Professional.
The full administrative installation of MS Office XP Professional requires approximately
650 MB of disk space.
</para>
<para>
When the MS Office XP Professional product has been installed to the administrative network
share, the product can be installed onto a workstation by executing the normal setup program.
The installation process now provides a choice to either perform a minimum installation
or a full local installation. A full local installation takes over 100 MB of disk space.
A network workstation (minimum) installation requires typically 10 MB to 15 MB of
local disk space. In the latter case, when the applications are used, they load over the network.
</para>
<para>
<indexterm><primary>Service Packs</primary></indexterm>
<indexterm><primary>Microsoft Office</primary></indexterm>
Microsoft Office Service Packs can be unpacked to update an administrative share. This makes
it possible to update MS Office XP Professional for all users from a single installation
of the service pack and generally circumvents the need to run updates on each network
Windows client.
</para>
<para>
The default location for MS Office XP Professional data files can be set through registry
editing or by way of configuration options inside each Office XP Professional application.
</para>
<para>
<indexterm><primary>OpenOffice</primary></indexterm>
OpenOffice.Org OpenOffice Version 1.1.0 can be installed locally. It can also
be installed to run off a network share. The latter is a most desirable solution for office-bound
network users and for administrative staff alike. It permits quick and easy updates
to be rolled out to all users with a minimum of disruption and with maximum flexibility.
</para>
<para>
The process for installation of administrative shared OpenOffice involves download of the
distribution ZIP file, followed by extraction of the ZIP file into a temporary disk area.
When fully extracted using the unzipping tool of your choosing, change into the Windows
installation files directory then execute <command>setup -net</command>. You are
prompted on screen for the target installation location. This is the administrative
share point. The full administrative OpenOffice share takes approximately 150 MB of disk
space.
</para>
<sect3>
<title>Comments Regarding Software Terms of Use</title>
<para>
Many single-user products can be installed into an administrative share, but
personal versions of products such as Microsoft Office XP Professional do not permit this.
Many people do not like terms of use typical with commercial products, so a few comments
regarding software licensing seem important.
</para>
<para>
Please do not use an administrative installation of proprietary and commercially licensed
software products to violate the copyright holders' property. All software is licensed,
particularly software that is licensed for use free of charge. All software is the property
of the copyright holder unless the author and/or copyright holder has explicitly disavowed
ownership and has placed the software into the public domain.
</para>
<para>
Software that is under the GNU General Public License, like proprietary software, is
licensed in a way that restricts use. For example, if you modify GPL software and then
distribute the binary version of your modifications, you must offer to provide the source
code as well. This restriction is designed to maintain the momentum
of the diffusion of technology and to protect against the withholding of innovations.
</para>
<para>
Commercial and proprietary software generally restrict use to those who have paid the
license fees and who comply with the licensee's terms of use. Software that is released
under the GNU General Public License is restricted to particular terms and conditions
also. Whatever the licensing terms may be, if you do not approve of the terms of use,
please do not use the software.
</para>
<para>
<indexterm><primary>GPL</primary></indexterm>
Samba is provided under the terms of the GNU GPL Version 2, a copy of which is provided
with the source code.
</para>
</sect3>
</sect2>
<sect2 id="ch4wincfg">
<title>Windows Client Configuration</title>
<para>
Christine needs to roll out 130 new desktop systems. There is no doubt that she also needs
to reinstall many of the notebook computers that will be recycled for use with the new network
configuration. The smartest way to handle the challenge of the roll-out program is to build
a staged system for each type of target machine, and then use an image replication tool such as Norton
Ghost (enterprise edition) to replicate the staged machine to its target desktops. The same can
be done with notebook computers as long as they are identical or sufficiently similar.
</para>
<procedure id="sbewinclntprep">
<title>Windows Client Configuration Procedure</title>
<step><para>
<indexterm><primary>WINS</primary></indexterm>
<indexterm><primary>DHCP</primary></indexterm>
Install MS Windows XP Professional. During installation, configure the client to use DHCP for
TCP/IP protocol configuration. DHCP configures all Windows clients to use the WINS Server
address that has been defined for the local subnet.
</para></step>
<step><para>
Join the Windows Domain <constant>PROMISES</constant>. Use the Domain Administrator
username <constant>root</constant> and the SMB password you assigned to this account.
A detailed step-by-step procedure for joining a Windows 200x/XP Professional client to
a Windows Domain is given in <link linkend="appendix"/>, <link linkend="domjoin"/>.
Reboot the machine as prompted and then log on using the Domain Administrator account
(<constant>root</constant>).
</para></step>
<step><para>
Verify <constant>DIAMOND</constant> is visible in <guimenu>My Network Places</guimenu>,
that it is possible to connect to it and see the shares <guimenuitem>accounts</guimenuitem>,
<guimenuitem>apps</guimenuitem>, and <guimenuitem>finsvcs</guimenuitem>, and that it is
possible to open each share to reveal its contents.
</para></step>
<step><para>
Create a drive mapping to the <constant>apps</constant> share on the server <constant>DIAMOND</constant>.
</para></step>
<step><para>
Perform an administrative installation of each application to be used. Select the options
that you wish to use. Of course, you can choose to run applications over the network, correct?
</para></step>
<step><para>
Now install all applications to be installed locally. Typical tools include Adobe Acrobat,
NTP-based time synchronization software, drivers for specific local devices such as fingerprint
scanners, and the like. Probably the most significant application for local installation
is antivirus software.
</para></step>
<step><para>
Now install all four printers onto the staging system. The printers you install
include the accounting department HP LaserJet 6 and Minolta QMS Magicolor printers. You will
also configure identical printers that are located in the financial services department.
Install printers on each machine following the steps shown in the Windows client printer
preparation procedure below.
</para></step>
<step><para>
<indexterm><primary>defragmentation</primary></indexterm>
When you are satisfied that the staging systems are complete, use the appropriate procedure to
remove the client from the domain. Reboot the system and then log on as the local administrator
and clean out all temporary files stored on the system. Before shutting down, use the disk
defragmentation tool so that the file system is in optimal condition before replication.
</para></step>
<step><para>
Boot the workstation using the Norton (Symantec) Ghosting diskette (or CD-ROM) and image the
machine to a network share on the server.
</para></step>
<step><para>
<indexterm><primary>Windows security identifier</primary><see>SID</see></indexterm>
<indexterm><primary>SID</primary></indexterm>
You may now replicate the image to the target machines using the appropriate Norton Ghost
procedure. Make sure to use the procedure that ensures each machine has a unique
Windows security identifier (SID). When the installation of the disk image has completed, boot the PC.
</para></step>
<step><para>
Log on to the machine as the local Administrator (the only option), and join the machine to
the Domain, following the procedure set out in <link linkend="appendix"/>, <link linkend="domjoin"/>. The system is now
ready for the user to log on, provided you have created a network logon account for that
user, of course.
</para></step>
<step><para>
Instruct all users to log on to the workstation using their assigned username and password.
</para></step>
</procedure>
<procedure id="sbewinclntptrprep">
<title>Windows Client Printer Preparation Procedure</title>
<step><para>
Click <menuchoice>
<guimenu>Start</guimenu>
<guimenuitem>Settings</guimenuitem>
<guimenuitem>Printers</guimenuitem>
<guiicon>Add Printer</guiicon>
<guibutton>Next</guibutton>
</menuchoice>. Do not click <guimenuitem>Network printer</guimenuitem>.
Ensure that <guimenuitem>Local printer</guimenuitem> is selected.
</para></step>
<step><para>
Click <guibutton>Next</guibutton>. In the
<guimenuitem>Manufacturer:</guimenuitem> panel, select <constant>HP</constant>.
In the <guimenuitem>Printers:</guimenuitem> panel, select the printer called
<constant>HP LaserJet 6</constant>. Click <guibutton>Next</guibutton>.
</para></step>
<step><para>
In the <guimenuitem>Available ports:</guimenuitem> panel, select
<constant>FILE:</constant>. Accept the default printer name by clicking
<guibutton>Next</guibutton>. When asked, <quote>Would you like to print a
test page?,</quote> click <guimenuitem>No</guimenuitem>. Click
<guibutton>Finish</guibutton>.
</para></step>
<step><para>
You may be prompted for the name of a file to print to. If so, close the
dialog panel. Right-click <menuchoice>
<guiicon>HP LaserJet 6</guiicon>
<guimenuitem>Properties</guimenuitem>
<guisubmenu>Details (Tab)</guisubmenu>
<guimenuitem>Add Port</guimenuitem>
</menuchoice>.
</para></step>
<step><para>
In the <guimenuitem>Network</guimenuitem> panel, enter the name of
the print queue on the Samba server as follows: <constant>\\DIAMOND\hplj6a</constant>.
Click <menuchoice>
<guibutton>OK</guibutton>
<guibutton>OK</guibutton>
</menuchoice> to complete the installation.
</para></step>
<step><para>
Repeat the printer installation steps above for both HP LaserJet 6 printers
as well as for both QMS Magicolor laser printers.
</para></step>
</procedure>
</sect2>
<sect2>
<title>Key Points Learned</title>
<para>
How do you feel? You have built a capable network, a truly ambitious project.
Future network updates can be handled by
your staff. You must be a satisfied manager. Let's review the achievements.
</para>
<itemizedlist>
<listitem><para>
A simple firewall has been configured to protect the server in the event that
the ISP firewall service should fail.
</para></listitem>
<listitem><para>
The Samba configuration uses measures to ensure that only local network users
can connect to SMB/CIFS services.
</para></listitem>
<listitem><para>
Samba uses the new <constant>tdbsam</constant> passdb backend facility.
Considerable complexity was added to Samba functionality.
</para></listitem>
<listitem><para>
A DHCP server was configured to implement dynamic DNS (DDNS) updates to the DNS
server.
</para></listitem>
<listitem><para>
The DNS server was configured to permit DDNS only for local network clients. This
server also provides primary DNS services for the company Internet presence.
</para></listitem>
<listitem><para>
You introduced an application server as well as the concept of cloning a Windows
client in order to effect improved standardization of desktops and to reduce
the costs of network management.
</para></listitem>
</itemizedlist>
</sect2>
</sect1>
<sect1>
<title>Questions and Answers</title>
<para>
</para>
<qandaset defaultlable="missed01" type="number">
<qandaentry>
<question>
<para>
What is the maximum number of account entries that the <parameter>tdbsam</parameter>
passdb backend can handle?
</para>
</question>
<answer>
<para>
The tdb data structure and support system can handle more entries than the number of
accounts that are possible on most UNIX systems. A practical limit would come into
play long before a performance boundary would be anticipated. That practical limit
is controlled by the nature of Windows networking. There are few Windows file and
print servers that can handle more than a few hundred concurrent client connections.
The key limiting factors that predicate offloading of services to additional servers
are memory capacity, the number of CPUs, network bandwidth, and disk I/O limitations.
All of these are readily exhausted by just a few hundred concurrent active users.
Such bottlenecks can best be removed by segmentation of the network (distributing
network load across multiple networks).
</para>
<para>
As the network grows, it becomes necessary to provide additional authentication
servers (domain controllers). The tdbsam is limited to a single machine and cannot
be reliably replicated. This means that practical limits on network design dictate
the point at which a distributed passdb backend is required; at this time, there is
no real alternative other than ldapsam (LDAP).
</para>
<para>
The guideline provided in <emphasis>TOSHARG2</emphasis>, Chapter 10, Section 10.1.2,
is to limit the number of accounts in the tdbsam backend to 250. This is the point
at which most networks tend to want backup domain controllers (BDCs). Samba-3 does
not provide a mechanism for replicating tdbsam data so it can be used by a BDC. The
limitation of 250 users per tdbsam is predicated only on the need for replication,
not on the limits<footnote><para>Bench tests have shown that tdbsam is a very
effective database technology. There is surprisingly little performance loss even
with over 4000 users.</para></footnote> of the tdbsam backend itself.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Would Samba operate any better if the OS level is set to a value higher than 35?
</para>
</question>
<answer>
<para>
No. MS Windows workstations and servers do not use a value higher than 33. Setting this to a value
of 35 already assures Samba of precedence over MS Windows products in browser elections. There is
no gain to be had from setting this higher.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Why in this example have you provided UNIX group to Windows Group mappings for only Domain Groups?
</para>
</question>
<answer>
<para>
At this time, Samba has the capacity to use only Domain Groups mappings. It is possible that at
a later date Samba may make use of Windows Local Groups, as well as of the Active Directory special
Groups. Proper operation requires Domain Groups to be mapped to valid UNIX groups.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Why has a path been specified in the <parameter>IPC$</parameter> share?
</para>
</question>
<answer>
<para>
This is done so that in the event that a software bug may permit a client connection to the IPC$ share to
obtain access to the file system, it does so at a location that presents least risk. Under normal operation
this type of paranoid step should not be necessary. The use of this parameter should not be necessary.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Why does the &smb.conf; file in this exercise include an entry for <smbconfoption name="smb ports"/>?
</para>
</question>
<answer>
<para>
The default order by which Samba-3 attempts to communicate with MS Windows clients is via port 445 (the TCP port
used by Windows clients when NetBIOS-less SMB over TCP/IP is in use). TCP port 139 is the primary port used for NetBIOS
over TCP/IP. In this configuration Windows network operations are predicated around NetBIOS over TCP/IP. By
specifying the use of only port 139, the intent is to reduce unsuccessful service connection attempts.
The result of this is improved network performance. Where Samba-3 is installed as an Active Directory Domain
member, the default behavior is highly beneficial and should not be changed.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
What is the difference between a print queue and a printer?
</para>
</question>
<answer>
<para>
A printer is a physical device that is connected either directly to the network or to a computer
via a serial, parallel, or USB connection so that print jobs can be submitted to it to create a
hard copy printout. Network-attached printers that use TCP/IP-based printing generally accept a
single print data stream and block all secondary attempts to dispatch jobs concurrently to the
same device. If many clients were to concurrently print directly via TCP/IP to the same printer,
it would result in a huge amount of network traffic through continually failing connection attempts.
</para>
<para>
A print server (like CUPS or LPR/LPD) accepts multiple concurrent input streams or
print requests. When the data stream has been fully received, the input stream is closed,
and the job is then submitted to a sequential print queue where the job is stored until
the printer is ready to receive the job.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Can all MS Windows application software be installed onto an application server share?
</para>
</question>
<answer>
<para>
Much older Windows software is not compatible with installation to and execution from
an application server. Enterprise versions of Microsoft Office XP Professional can
be installed to an application server. Retail consumer versions of Microsoft Office XP
Professional do not permit installation to an application server share and can be installed
and used only to/from a local workstation hard disk.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Why use dynamic DNS (DDNS)?
</para>
</question>
<answer>
<para>
When DDNS records are updated directly from the DHCP server, it is possible for
network clients that are not NetBIOS-enabled, and thus cannot use WINS, to locate
Windows clients via DNS.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Why would you use WINS as well as DNS-based name resolution?
</para>
</question>
<answer>
<para>
WINS is to NetBIOS names as DNS is to fully qualified domain names (FQDN). The FQDN is
a name like <quote>myhost.mydomain.tld</quote> where <parameter>tld</parameter>
means <constant>top-level domain</constant>. A FQDN is a longhand but easy-to-remember
expression that may be up to 1024 characters in length and that represents an IP address.
A NetBIOS name is always 16 characters long. The 16<superscript>th</superscript> character
is a name type indicator. A specific name type is registered<footnote><para>
See <emphasis>TOSHARG2</emphasis>, Chapter 9, for more information.</para></footnote> for each
type of service that is provided by the Windows server or client and that may be registered
where a WINS server is in use.
</para>
<para>
WINS is a mechanism by which a client may locate the IP Address that corresponds to a
NetBIOS name. The WINS server may be queried to obtain the IP Address for a NetBIOS name
that includes a particular registered NetBIOS name type. DNS does not provide a mechanism
that permits handling of the NetBIOS name type information.
</para>
<para>
DNS provides a mechanism by which TCP/IP clients may locate the IP address of a particular
hostname or service name that has been registered in the DNS database for a particular domain.
A DNS server has limited scope of control and is said to be authoritative for the zone over
which it has control.
</para>
<para>
Windows 200x Active Directory requires the registration in the DNS zone for the domain it
controls of service locator<footnote><para>See TOSHARG2, Chapter 9, Section 9.3.3.</para></footnote> records
that Windows clients and servers will use to locate Kerberos and LDAP services. ADS also
requires the registration of special records that are called global catalog (GC) entries
and site entries by which domain controllers and other essential ADS servers may be located.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
What are the major benefits of using an application server?
</para>
</question>
<answer>
<para>
The use of an application server can significantly reduce application update maintenance.
By providing a centralized application share, software updates need be applied to only
one location for all major applications used. This results in faster update roll-outs and
significantly better application usage control.
</para>
</answer>
</qandaentry>
</qandaset>
</sect1>
</chapter>
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