Booting into Linux

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