by July 7, 2001 0 comments



Boot disk

This method
uses a floppy boot disk. Apart from the fact that the disk usually wears out
due to frequent usage, this method needs the BIOS to be set to boot first
from the floppy disk. This also involves significant virus risks and should
be avoided unless absolutely required. This method is often used to boot up
the first time to copy the files required for LoadLin.

LILO

LILO stands
for the bootstrap Linux Loader. This bootstrap loader can be used to load
other operating systems such as Win 95/98. However, some versions of Win NT
seem to object to LILO, especially during installation. Some anti-virus
software and other tools can also directly interfere with LILO. By its very
nature, LILO is recommended only for people who boot into Linux more often
than into the other OS in a dual boot machine. The default behavior of LILO
can be modified by editing the file /etc/lilo.conf. For more information
type

$man
lilo.conf

If you wish to use LILO as
the bootup manager, during the install, choose to write LILO onto the MBR.
Typically, during a bootup, LILO loads first and presents a menu to the
user. The user can decide to choose which OS to start. LILO then transfers
control to the required operating system.

LoadLin

LoadLin is a
tool written to help load Linux from Windows machines. This approach is best
suited for people who boot into Linux infrequently. In this situation, the
access method to Linux is to double click an icon while in Windows to start
Linux. In this approach, nothing is written onto the MBR and there’s a
complete separation between Linux and other operating systems. To use this
method, first choose to write LILO onto the first sector of the Linux
partition. In order to use LoadLin, boot into Linux and login as root. You
need to extract the exact vmlinuz file that is residing in the /boot
directory. This file needs to be copied onto a DOS-formatted floppy. If your
Linux partition is on the first hard disk (hda), here’s a sequence of
commands to do the same.

# cd /boot

# mcopy
vmlinuz a:

After this step, you need to
know exactly where the Linux bootup code is stored. This information is
provided by fdisk, which’ll reveal where exactly the main / partition is
stored.

# fdisk /dev/hda

This is followed by
“p” to print out partition information. After it’s known where
the Linux root partition is (/dev/hda7, for example), you can reboot into
Windows by using the command

# reboot

In Windows, create a
directory called Linux. Into this directory, copy the Loadlin.exe file found
in the /dosutils directory. In addition, create a batch file in the same
directory with the following command

@ loadlin
vmlinuz root = “/dev/hda7”

Then, from Windows create a
shortcut to the batch file and place it on the desktop. Adjust the
properties of the shortcut so that the batch file will execute in MS-DOS
mode only. Change the icon and rename it appropriately. You’re all set to
go now. If you need to start Linux, just double click on the icon, and you’re
on your way.

Interacting with NT

You might ask
yourself why adding Win NT or 2000 machines should be any different from
adding Win 9x machines. However, there are significant differences in the
SMB implementations between versions of Microsoft’s own operating systems.
Even the password algorithms used by the two operating systems are
different. Win 9x machines don’t actually participate in a Win NT domain
the way NT does. The domain controller in this case is used purely for
authentication.

If you want to use Win 2000
machines in a Samba domain, you’ll need to upgrade to Samba 2.0.7 (Zoot
ships with 2.0.6, so you’ll have to download the updated RPMs). There are
a few subtle changes in 2000, most of which have been addressed in this
release. There are a few outstanding bugs though, but no show-stoppers. Note
that Win 2000 is currently only supported in the backwards compatibility
(with NT PDC) mode, and not in its native domain controller mode.

Adding a Samba server to a
Win NT domain

To get a
Samba server to join a Win NT domain, you must first create a machine
account for the server in the PDC’s SAM (Security Accounting Manager)
database. You can do this using the “Server Manager for Domains”
utility on the PDC. The machine account is created using the netbios name of
the Samba server, which is usually, but not necessarily, its host name.

Once you’ve created the
machine account, you need to configure the smb.conf file. Apart from the
standard configuration, you need to make the following changes:

workgroup = NTDOM (Assume
that the domain name is NTDOM)

security = domain

password server = NTDOMPDC
NTDOMBDC1 NTDOMBDC2

where NTDOMPDC is the name of
the domain controller, NTDOMBDC[1,2] are the names of the backup domain
controllers, and SAMBA is the netbios name of the samba server.

Now, before restarting the
smbd daemons, give the command

# smbpasswd -j NTDOM -r
NTDOMPDC

This command will create a
file called SAMBA.NTDOM.mac in your /etc/ directory, containing the machine
account password for the Samba server.

Assuming all goes well, you
should get a message saying

smbpasswd :
Joined domain NTDOM

Adding an NT server to a

To add
a Win NT machine to a Samba domain, you need to create a user entry
for it in the password file. This is the Samba equivalent of creating a
machine account in the SAM database. The username should be the name of the
machine, appended with a “$”. Set no password, and set the home
directory to /dev/null, and shell to /bin/false. (You might have to escape
the “$” on the command line with a “\”, if required)

# useradd ntserver$ -s /bin/false -d /dev/null

The next step
is to go to the NT machine, and set the domain name to SAMBADOM (where
SAMBADOM is the domain name). Take care not to check the “create a
machine account” check box. This feature is not yet supported. You
should get a message saying “Welcome
to the SAMBADOM domain”.

Understanding server
configuration options

If you look
at the man page for the smb.conf file (man 5 smb.conf), you’ll find a
number of configuration options that you can use to tweak the performance
and customize your Samba configuration further. Due to the lack of space
here, I’ll take a look at only a few configuration options.

One of the more misunderstood
configuration parameters is the “security=” option. We’ll take a
brief look at what the various options mean.

security=share

This is the conventional, and
most brain-dead option available. Shares exported will be available to any
machine in the workgroup without further authentication. This is commonly
used for machines sharing public shares, CD-ROMs, etc. Use this only when
you have no security concerns whatsoever.

security=server

Server level security is used
when you want the Samba server to authenticate users against another Samba
or Windows NT machine acting as a domain controller. This is a good idea
when you have a number of machines on your network, with users needing to
logon to the domain to be able to access the shares. In this case, you’ll
have to configure the “password server” parameter to specify the
names of the authentication servers (normally the PDC and BDC).

security=user

In this scheme, the Samba
server actually acts as a workgroup controller, authenticating Windows NT
and Win 9x clients. A separate user list has to be maintained, and users are
added using the “smbpasswd” command. In this case, the Samba
server maintains its equivalent of an NT SAM database.

security=domain

Domain level security is used
in the case described above, when adding a Samba server to a Win NT domain.
Here too, you’ll need to specify the “password server”
parameter. So how’s this different to the “security=server”
configuration? For one, when using server level security, the Samba server
will open and maintain a network connection to the domain controller during
the entire session. This can be a significant drain on network resources. In
domain level security, a connection is established for exchanging
authentication information only.

There are some new parameters
in Samba 2.0.7 as well. Most of these deal with the new utmp and wtmp
support (experimental, I might add) included in this version. This will
enable users logged in via Samba to be seen using the “who”
command, and all login information to be recorded in the system logs, not
just the samba logs. You’ll need to specifically compile support for this
using the
“–with-utmp” flag to “configure”.

Samba development

Samba
development is progressing at an extremely hectic pace. There are currently
four trees under active development (For those new to the open source style
of development, a "tree" consists of all the latest source code of
the software, to which developers have access. Developers "check
in" portions of code they are working on, and then "check
out" the new code for others to test and debug when they have
finished).

There is the SAMBA_STABLE
branch, which has the regularly released "stable code", for you
and me to use. New features are not introduced into this tree until they’ve
been thoroughly tested in unstable versions. The stable Samba tree at this
time doesn’t have the ability to be a domain controller for Win NT
machines.

The second branch is the
SAMBA_TNG branch, which is where the main thrust of development is going on
at the moment. TNG stands for "The Next Generation", and includes
all the "cool code", such as domain controller for NT and Win 2000
machines, support for NT- specific administrative tools such as "User
Manager for Domains", and trust relationships, etc.

The Third branch is the
SAMBA_HEAD branch, which is the successor to the current 2.0.x series. It
contains improved file and print sharing services and NT file permissions
support. However, it contains no NT PDC support.

The last and final branch is
the HEAD_WITH_TNG branch, which is exactly what you might imagine from its
name.

The most interesting of these
branches is the SAMBA_TNG branch, which focuses on Win NT PDC controller
code. It currently suffers from poor file serving ability, but code mergers
with the SAMBA_HEAD branch will take care of this problem in the near
future.

So if you’re a hacker, or
kid with a network and time to spare, download the TNG or HEAD branch and
play with the code. Finding bugs or contributing documentation is the
easiest way to help the development effort, if you’re not a developer
yourself.

Babu Kalakrishnan, a Director at Sankya System & Objects, Bangalore www://www.sankya.com

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