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.