Skype - Essay Example

DQ1: Skype Skype uses VoIP (Voice over Internet Protocol), which is a service that allows us to make calls from a PC to an ordinary phone. Valdes and Roos (2012) state that, “VoIP can turn a standard Internet connection into a way to place free phone calls.” The voice call passes both through the Internet and through a telephone network. However, the mechanism is a bit complex as compared to an ordinary phone-to-phone call. The mechanism comes under the concept of Internet Telephony, which supports voice calls, SMS, and voice messaging services that are initiated through the internet and are intended for an ordinary phone.

To understand the generation of a VoIP telephone call from Skype, let’s consider both the sender’s side and the receiver’s side. Mr. A sends a telephone call from Skype to Mr. B’s phone. First of all a media channel is setup. The analog voice signals are converted into digital signals by the sound card, which are then encoded into packets and sent over the internet. When all signals have been packetized, they are then sent to a packet-switched network in Mr. B’s area, as Internet Protocol (IP) packets.

VoIP operators also set up gateways to act as a link between the caller and the called one (Wolf & Barnes 2011:2). Mr. A’s PC was the originating gateway, and the packet-switched network which received the packets was the end gateway, which will send the voice signals to the public switched telephone network (PSTN). PSTN, then, will direct these signals to Mr. B’s telephone as regular telephone calls. This is the process accomplished from the sender’s side, who bypasses the local telephone network and its charges.

Now, when Mr. B receives the call on his telephone, the process goes like this. The packets received on the packet-switched network as IP packets are decoded. The digital signals are converted back into analog signals, which finally produce the voice stream as sent by Mr. A. Hence, we see that when Skype makes calls from internet to an ordinary phone, both the internet and the PSTN are involved. Although you have to pay for this service, yet it is much cheaper than regular phone-to-phone calls.

That is why this service is widely in use today. References Valdes, R & Roos, D 2012, ‘How VoIP works’, How Stuff Works, viewed 1 March 2012, Wolf, K.H, & Barnes, R 2011, ‘Calling over the internet’, VoIP Emergency Calling: Foundations and Practice, John Wiley and Sons, USA. DQ2: Malicious Acts The concept is called ‘packet sniffing’. Thomas has used a packet sniffer to capture packets not intended for him. Packet sniffing is “the process of capturing and interpreting live data as it flows across a network in order to better understand what is happening on that network” (Sanders 2007:2).

Packet sniffer is a hardware or software that captures network traffic or packets of data. The packet sniffer must be on the same wire which is linking the two computers with each other. Since, packet sniffers are not easy to detect, Thomas might have installed a Trojan on Ali or Jim’s computer, and might have run a packet sniffer from their system, making the sniffer stay on the same wire. Thus, the network card is set into a promiscuous mode. Now, Thomas can view all usernames and passwords because “within a given network, username and password information is generally transmitted in clear text which means that the information would be viewable by analyzing the packets being transmitted” (Bradley 2012).

Hence, with the use of packer sniffer, Thomas can read all unencrypted data being transferred between Ali and Jim. This type of hacking is also called eavesdropping in which the Hacker can actually monitor the network traffic. Thomas, through eavesdropping, can perform many malicious activities through gaining control over the transmission of packets, by eavesdropping on the Internet Protocol (IP) based network. It is, again, a sniffer technology which captures data packets. Thomas can gain access to user accounts and privileges; can make the conversation confusing for Ali and Jim to understand; and, can use the information obtained in criminal activities.

He can also modify or tamper with the packets by placing a tap on the network line to interrupt packet transmission as they leave the sender’s point. He can use his packet capturing techniques to steal important information being exchanged between Ali and Jim. He can totally stop data packets from transmission. Hence, there are a lot of malicious activities that he can do by gaining control over the transmission of data packets between the sender and the receiver. In case of wireless networking, it becomes very important to encrypt all information that is being sent as data packets to the receiver.

This prevents the hacker or packet sniffer to understand the data, even if it gets hacked. (Note for QAD: The two questions and their references have been separated as per the customer’s instructions.) References Bradley, T 2012, 'Introduction to Packet Sniffing’, About.com, viewed 1 March 2012, Sanders, C 2007, Practical Packet Analysis: Using Wireshark to Solve Real-World Network Problems, No Starch Press, USA.