1. Abstract
Data communication with the use of Linux
system environment applications has in recent years running and
practicing as a platform on the Lab’s computer systems and
networking at the School of Engineering in South Bank University,
which is located in the area where from is quite centrally of the
heart of city of London.
The aims and objectives of these based Linux
experiments are to putting students into implementing their practices
besides their theory in the Unit of Data Communication, from which,
among others, I am is one of those students who involved exercising
these practices. Therefore, my aim here is to deliver a report in
which I intend to describing, analysis and comment thought those
processes of Linux based practiced from which I have gone through.
Thus, there are several more experiments than this report can tell,
however, I am focused on is Linux Fundamental experiment.
Based on two Linux working paper sheets provided from
Dr. Perry Xiao and Dr Ya Bao for practicing on three Pentium
processors computers which has then installed four hardware 3Com Fast
Ethernet Link Networking Cards (two cards in computer No.2 and one
card in each other computers that is computer No.1 and No.3) which
cables connection within cards and Linux RedHat 7.0 operating system
in text mode environment applications. Through these working tools
provided and its interaction processing of Linux software program in
term of number of features, such as for example one is the use of
virtual terminals, it has represent the most powerful features and
aspects of Linux in today in ours world of data communicating computer
networks, and although Linux, unlikely as that “Windows”, is just
began to a new stages of efficiency its program and producing more of
sources and the more speed of growing of users.
Now, we going to explores more about Linux and it
networking. Please go with me into the Lab.
2.
Introduction
The Lab located on the fifth floor on the Tower
Block. We are on a group of four MSc.CSN students (Amari M., Asharat
M., Mounteng C., and myself), and among others in my group, I am login
as “root”.
As
figure show below is a system network in our lab at the sbu
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PC1
One
3Com Ethernet Card
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PC2
Two 3Com Ethernet Cards
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PC3
One
3Com Ethernet Card
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3.
Practising
3.1
Logging In and Create users
As a “root” user, it is mean that I am a user who
has access to all files on the system and is responsible for creating
other users as well as to maintenance it system because I can either
installing or deleting programs, etc., in short I have the full access
to do everything that I like. However, as a root user I may need also
to be considered myself to be more responsible and be more careful
when user Linux system, because as I am a root, a “super user, who
has the authority to do anything, anywhere in the entire system”
Viki Stanfield & Roderick W. Smith (Linux System Administration,
SYBEX Inc., 2001, p14) and if that I do a mistake such as deleting
system files, if then, I actually is the one who make the system going
wrong and the system would turned into a mal function. Therefore, as a
rootuser, I really need to be aware of these responsibilities.
As the below demonstrate how I am as a rootuser and
to create other users such as has names “labuser” and
“labuser1”.
That is really great, as you see, I have just created
two new users in a minute, so that now it is allowed for new user as
“labuser” and user as “labuser1” can login and use the Linux
system.
3.2 Create text file and logout
Let us now allow “labuser” to login and going to
create and write a text file readme.txt than logout again.
3.3 Virtual Terminals
In Linux, virtual terminals provided other users such
as “labuser” and user as “labuser1 can login and use the Linux
system together with me either they login in other computers such as
computer No.2 and computer No.3 if I using computer No.1, or even they
can using the same computer as I’m in actual using because Linux
system “provides access to Virtual Terminals, which allow to have
more than one login session at a time”. Perry Xiao (Linux
Fundamental, a Linux lecture paper, School of Engineering, South Bank
University, London). It is so cool, and not just only that, it is also
allow you to changing between these virtual terminals as fast as you
could by using <alt> and Fn keys.
But how then it is possible that Linux based system
and these mentioned Virtual Terminals are communicating with each
other, or even say if I login computer No.1 but using computer No.2 as
a terminal?
The answer is yes, it can and it is possible because,
as I have described earlier, these 3 computers are physically link
with each other through cables and 3Com Ethernet Network Cards
connection. In addition, and alternatively, it can link other
computers with cables through serial ports to these 3 computers as
described above which has Linux based system in its, but then these
alternative computers can only be used as the so called “dumb
terminals” access. Thus dumb terminals have limited role to play
because as they are connected to the host computers only through the
physical serial ports rather than 3Com Ethernet Network Cards, so they
don’t really acting as intelligent as other host computers which
they has Linux based system and 3Com Ethernet Network Cards installed.
However, dumb terminals can transmit characters that typed from the
keyboard to the host computers and then can also display characters,
which received from host computers.
3.4 Check out who you are
Here I have to say that it is in Linux system working
environment, it is extremely very nice that you should know is that
you will always find out who you are and in whatsoever situation it
is, either you are on your own or you are user at the same time with
other users in one computer, because Linux provided you a command #whoami
and therefore by typing in this command, it is obvious will
immediately identify who user you are. This allowed for users the
extreme confidence in the case of virtual terminals because even if
three users login to the same computer and to use simultaneously, but
they always can checkout and to know who they are and therefore would
not be confusing or messing up its system.
As mentioned earlier the role of “rootuser” is
tremendous important and in fact it is absolutely a “King” user in
Linux system because it has the access and authority to do everything
and anything in anywhere in the entire Linux system files and system
directories. However, with Linux system command #su it will
allows any other users to become a “rootuser”, nevertheless if
only other users can be trusted by root and can obtain for
themselves a root’s password. If then, the user who has the root’s
password, can certainly also become a King-user because now the user
can have the access to do anything and everything in anywhere whereas
was restricted to user’s own original identification either than
root.
As showed the above, has demonstrated “labuser2”
has been identify as well as has became a super user root by
command #su. Alternatively task, but it is absolutely really
nice to become rootuser, however, it is worth needed to mention here
is that when other user has obtained the permission as acting as
rootuser, it is necessarily now is to pay more attention and have more
responsibility because, when one has become super rootuser and then
make the wrong actions and mistake such as remove or deleting files,
it then can even harm the system and turn the system into darkness or
mal functionally. Therefore it is absolutely strong to become a super
rootuser but as the same time it also strongly needed responsible of
maintaining system security.
3.5 File system
As
indicated in the Lab’s Linux experiment work sheet from Dr. Perry
Xiao and Dr. Ya Bao:
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Most Unix systems have a standard layout for files, so that system
resources and programs can be easily located.
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Directory tree, starts at the / directory, also known as the root
directory.
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Related directly underneath / are some important subdirectories: /bin,
/etc, /dev, and /usr, among others. These directories in turn contain
other directories, which contain system configuration files, programs,
etc.
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In particular, each user
has a home directory, which is the directory set-aside for that user
to store his files.
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When log onto a LINUX system you are placed into your home directory.
From here you can always go all the way back up to the root directory.
Yes, that is absolutely true, as mentioned earlier
the “root” user, the user who has access to all files on the
system and is responsible for creating other users as earlier
demonstrated. The root directory is “/” is also the main directory
of Linux system files, and which is where the main /usr, /etc, /bin,
/dev directories start.
In the section below I can demonstrate that, when
login to Linux working interface, one can always can find out exactly
where one are by using the command pdw because “it pwd
command will tell us the path from the root directory to the directory
currently one are in” Perry Xiao (Linux Lecturer working paper),
thus the below will shows that I am at the movement at the directory
of /home/labuser directory.
And
then from here, I can also see the list of all files in the current
directory of /home/labuser by using command #ls
[root@localhost
labuser]# ls
Desktop
readme.txt
As
showed the above, in the directory of Desktop, whereas contain a file
readme.txt
As
earlier pointed out in the Linux working paper (Dr Perry Xiao),
subdirectories are also files, and files appeared in different color
in Linux (that is to say blue, green, pink, etc.,). The command ls
–la will listing out all these directories and files (included
hidden files usually are not shows), as the below:
What
we have to take a noted here is that to look at the information in
which command ls –la have given out to us, that is to say we
looked all these files above and to find out which one is a file and
which one is a directory. In order to do that, we simply to look at
the first character of a file, and if it is in the case of a letter
‘d’, it is indicated as a directory. Thus for-example, the above
files has showed, drwxr-xr-x2 labuser group1 4096 Dec 14 01:22
Desktop is actually a directory, whereas –rw-r- -r- -1 root
root 196 Dec 14 02:04 readme.txt is a text file.
Moreover,
we should also to take a noted here is that to looked as these (one
dot) and (two dots) and to remember that the one (.) is to tell
the current directory, and the (..) is to tell the up
directory. Thus the above showed our current directory is ‘labuser
group1’ and ‘root root’ is up directory. However, the first (.)
and (..) are not really real files, but it is very useful
when use combined together with other commands such as cd plus
dot and two dots, that is ( cd.) and (cd..), when to
changing between directories and moving around in Linux system. Other
dot files such as .bash and
.emacs are real system and text files which contain important
information and maintaining system configuration.
4.
Conclusion
As
I have showed some of the most powerful features of Linux based system
networking, and hopefully you will be agree with me to some extent.
Until here I would like to ask you a permission to make a stop for my
report because there is must more detail in Linux Fundamentals
experiment in which I have described and discussed in my LogBook. My
conclusion on Linux based system of networking from which I have
learned from the Lab at the sbu is quite tremendous optimistic,
because I think that the program as we learn have in recently years
and has as now represent a comprehensive and fundamental method of our
world today in Data Communication System and Networking, for example
the use of Linux system of virtual terminals has provided not merely
for multi users login in one computer and working simultaneously at a
time but also introduced a new working environment and showed of a new
stage of high-tech in Data Communication of computers system based
networking.
References
Viki Stanfield & Roderick W. Smith (2001), Linux
System Administration, SYBEX Inc., p14
Perry Xiao, Linux Fundamental, a Linux lecture paper, School of
Engineering, South Bank University, London.
