Websystem Tut8

Week 9 tut

1. On a linux machine run ifconfig and observe the output. How can you restrict the output to just one interface?

2. There is a command line tool that can be used to retrieve a particular web page. What is it and test that it works by retrieving the page start.it.uts.edu.au

wget

3. Some of the common ports used by various protocols have been discussed in the lecture. Find what ports the following are used on: Display Support Protocol, Quote of the Day, Trivial File Transfer, Network Time Protocol, NetBios Name Service

Command : netstat –anpe (in linux)??????

dsp              33/tcp    Display Support Protocol

dsp              33/udp    Display Support Protocol

qotd             17/tcp    Quote of the Day

qotd             17/udp    Quote of the Day

tftp             69/tcp    Trivial File Transfer

tftp             69/udp    Trivial File Transfer

ntp             123/tcp    Network Time Protocol

ntp             123/udp    Network Time Protocol

netbios-ns      137/tcp    NETBIOS Name Service    

netbios-ns      137/udp    NETBIOS Name Service    

netbios-dgm     138/tcp    NETBIOS Datagram Service

netbios-dgm     138/udp    NETBIOS Datagram Service

netbios-ssn     139/tcp    NETBIOS Session Service

netbios-ssn     139/udp    NETBIOS Session Service

User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. Using UDP, programs on networked computers can send short messages sometimes known as datagrams (using Datagram Sockets) to one another. UDP is sometimes called the Universal Datagram Protocol. The protocol was designed by David P. Reed in 1980.

The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. TCP provides reliable, in-order delivery of a stream of bytes, making it suitable for applications like file transfer and e-mail. It is so important in the Internet protocol suite that sometimes the entire suite is referred to as "the TCP/IP protocol suite." TCP is the transport protocol that manages the individual conversations between web servers and web clients. TCP divides the HTTP messages into smaller pieces, called segments, to be sent to the destination client. It is also responsible for controlling the size and rate at which messages are exchanged between the server and the client.

4. Before non text files can be sent over email they need to be encoded. There is a program on charlie that can do this (note: it is not on the linux machines in the labs). Pick a non text file and use this program to encode it (you may want to use redirection to save the output to a file). View and compare the contents of the original and encoded files.

MIME - Multi-purpose Internet Mail Extensions

5. What is one of the main advantages of using SSH over other protocols such as ftp and telnet?

More secure because users’ information is encrypted when it’s sent over the Internet.

Cisco Sales Work Opportunities

isco Sales Work Opportunities

Posted by elaine on 2008-05-12 10:01:48.847891 [Current Until: 2008-05-30 00:00:00] Can you please request your high potential students/candidates who have or going to achieve CCNA and CCNP certifications during their school graduation, to email me their resume at zafkhan@cisco.com ? I will call them to conduct their interviews. I appreciate your help and support. Regards Zafar P.S : The job require both CCNA and CCNP certifications. The person should have passion to work in Sales organization. Cisco Sales Associate Program (CSAP) ,in case you are not, it is graduate hiring program in which we hire college graduates with four years of engineering or computer science degree as Associates Systems Engineers (ASE), provide them extensive training and guarantee them a job a Systems Engineer (SE) in Cisco Sales organization in their country of citizenship after they graduate from the program successfully. During the CSAP program they are paid in full as Cisco employees with full benefits while they are being trained. Details of program are listed under (click on Associates Sales Engineer) http://www.cisco.com/go/sap Today the program is one year in duration and we provide CCNA and CCNP training in-house.We are planning to reduce the program duration if we can hire college graduates having CCNA and CCNP certification while they were completing their degrees. During hiring , I will look for followings attributes in candidates - Passion to work in Sales as Systems Engineer - 4 year college degree in engineering or sciences - Willing to relocate to Amsterdam or USA for the duration of program (6 to 12 months) and going to back to home country for job after graduating from CSAP program. - Leadership skills, a team player and have good communication skills. If your college/university produce CCNP certified people and they have 4 years degree , I will willing to partner with you to hire them into Cisco. Every year , I hire about 225 graduates from all over the world.

Chap 6 - Linuxgym

2)List cut
Create a file called "names.txt" containing only the first column of

/usr/local/linuxgym-data/census/femalenames.txt

in its existing order. Ensure that there are no other changes to the data.

A :

cat table.csv | cut -f1 -d,


6)Grep and regular expressions
Create a file called "natmat.txt" containing, IN THE ORIGINAL ORDER, only the lines of

/usr/local/linuxgym-data/census/femalenames.txt

starting with the string 'NAT' or 'MAT'. Ensure there is no extra white space in the file "natmat.txt".

Q:
egrep '^NAT|^MAT' /usr/local/linuxgym-data/census/femalenames.txt > natmat.txt

7)Name frequency
Create a bash script called namefreq.sh which takes one argument - a name. The output should be the FREQUENCY of that name's use, which is the entry in the second column of /usr/local/linuxgym-data/census/femalenames.txt

For example

./namefreq.sh ANA

will return

0.120

and nothing else.

Q :

#!/bin/bash

grep -w $1 ./table.csv | cut -f2 -d,

Single file word detection
Write a bash script called gender.sh which takes one argument - a name. The script should print "female" if the word appears in the file /usr/local/linuxgym-data/census/femalenames.txt, and "male" otherwise.

Hint: Redirect grep's stdout so it doesn't get printed, or use the grep "quiet" option.

A:

#!/bin/bash

grep -q $1 ./table.csv

if [ $? = 0 ]
then
echo female
else
echo male
fi

Rich Picture

http://openlearn.open.ac.uk/mod/resource/view.php?id=257790

Part 2: 3 Representing your experience of complexity

3.2 Complexity and rich pictures

This section is mostly concerned with thinking about your rich picture and the complex situation it depicts.

There are lots of ways of drawing a good rich picture and very few ways of drawing bad rich pictures. So my next strategy in supporting your learning, and your experience of this complex situation, is to propose a number of checks you might use to ensure you have not fallen into the trap of the less-effective rich picture.

Although my discussion will focus on rich pictures, I am also talking about the complexity the rich picture represents. I am using the task of generating a useful rich picture to illustrate the process of experiencing and capturing complexity.

Trap 1: representing the problem and not the situation

This trap is one of the most fundamental mistakes you can make in systems thinking. There are lots of metaphorical phrases in English that can entice you into the trap. We can talk about ‘the nub of the problem’, ‘the key issue’, ‘the basic problem’, ‘the real difficulty’ and so on.

Like all traps, once it has sprung, it can be very difficult to get out. The trap seriously limits one's ability to think about the situation in its full complexity. This is precisely because, by identifying every problematic feature as stemming from one single interpretation of the problem, you limit your possible ways of dealing with the situation to those that might be answers to this single problem. You have imposed simplicity on the situation, which does not reflect the very complexity that makes it problematic.

In contrast, one of the reasons this case study seems to be complex is precisely the difficulty of identifying anything that could be described as the key issue. It seems to be a tangle of interrelated key issues.

The whole point of a rich picture is to represent all you can about the situation. To identify the problem within the picture, or to include only the elements that seem problematic, is to prune out potentially important elements of the complexity.

So, the check for avoiding this trap is to ask:

• Does this rich picture represent the situation or is it just my interpretation of what the problem is? Does it include all the features noted as problematic?

Trap 2: the impoverished rich picture

A distinguishing feature of rich pictures that turn out to be useful seems to be they are just what they say they are, rich. If I take usefulness as the criterion, the useful rich pictures are the ones bursting with interest and activity. They don't seem to tell a single story, there are lots of stories going on simultaneously. They reveal stories you didn't consciously build into them.

How is such a rich picture to be achieved?

Use everything you find in the situation. This means incorporate everything you know about the situation. Either put things into the picture as you re-read the description; or make lists of the protagonists, the organisations, the structures, and then put them into the picture. Include people as well as the roles they inhabit.

Indicate the connections. Where the structural entities you listed above have connections and relationships between them, indicate what they are. There are all sorts of ways of doing this, especially if you ask yourself about the nature of the connection. You could use physical proximity (or distance) or representations of the nature of the connection (hearts, daggers drawn, telephones, deafness, walls of silence). Lots of people quite unconsciously use visual metaphors in their everyday language. (‘Every so often they drop a bombshell on this department.’ ‘We're swamped with memos.’ ‘We're drowning in paperwork.’) Talk to yourself about the situation and you may pick up clues about how to represent features of the situation. Arrows and lines tend to be less useful but they're not forbidden. Don't force the images, use the ones that seem to come naturally. There is no library of approved symbols.

Use all the geographical locations, if this is relevant.

Use all the processes. Include all the changes, and activities. Include impressions as well as reported facts.

Some people use computer clip-art to draw rich pictures. It rarely works in my view. Some essential quality seems to be missing. This quality might be ownership or engagement or it may be the very act of sitting at a computer keeps the activity at a rational level – it does not allow for the impressions and half-formed awareness to express themselves through the act of making marks directly on to paper.

The check for avoiding the impoverishment trap is to ask:

• Have I included everything I know about the situation in my representation of it?

Trap 3: interpretation, structure, and analysis

If you deliberately impose an interpretation or analysis on your picture, you preclude the possibility of seeing other, potentially more interesting, features later. Remember the rich picture is a representation of the complexity. If you structure that complexity, you are no longer representing it as you experience it. You also lose the possibility of using the drawing process itself as a means of encountering the complexity in all its fullness.

The trap takes a number of forms. Beware of representing events in their chronological sequence, either explicitly or implicitly. Also, organisational structure may take over and become the structure of the whole picture. Elements of other diagram forms may creep in. (Systems maps and influence diagrams can be quite a temptation.) Watch out for the temptations you are susceptible to. Artistic abilities, if you have them, can represent their own temptations – they too can be a part of the structuring trap.

It may be inevitable that interpretations suggest themselves as you draw. Stop yourself thinking ‘this is really about …’ One way of stopping this is to jot the idea down somewhere – not on your picture – in the form of a question. Once you've written it down, the idea is much less likely to keep popping up as if it were trying to ensure you won't forget it.

So, the check for avoiding this trap is to ask:

• Is this rich picture telling just one story or is it rich enough to suggest lots of stories about what's going on?

Trap 4: words and wordiness

I have seen some effective rich pictures with lots of words in them but they are quite rare in my experience. More often, lots of words make the rich picture less rich. Part of the later use of a rich picture might include looking for patterns. Words inhibit your ability to spot patterns.

If you do use speech bubbles, use what people say, not your interpretation, unless the bubble is about some general attitude. Examples might be ‘Aaagh!’, ‘Help!’, ‘Oops!’ – the sort of things found in comic books.

The check for avoiding this trap is to ask:

• Do I have to do a lot of reading to see the relationships between elements in the picture?

Trap 5: the final version trap

Ironically, the biggest mistake you can make, having got this far, is to assume your picture is finished. New realisations will crop up. Add these to your picture as you appreciate more and more of the complexity.

So, the check for avoiding this trap is to ask:

• Have I had any new insights about the complex situation since I last added something to this picture?