COMSATS INSTITUTE OF INFORMATION
AND TECHNOLOGY ISLAMABAD
NETWORK PROGRAMMING
ASSIGNMENT # 1
SUBMITTED BY:
MUHAMMAD BILAL MUNIR
REG #
FA08-BET-078
SUBMITTED TO :
MA’AM MADIHA KAZMI
DATE: 10/10/11
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OSI Model-Network Programming-Assignment Solution, Exercises of Network Programming
This is assignment solution which is part of Network Programming course and was submitted to Dr. Salman Azad at COMSATS Institute of Information Technology. It includes: Network, Programming, Model, Protocol, Internet, Layer, Presentation, Session, Transport, Application
Typology: Exercises
2011/2012
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COMSATS INSTITUTE OF INFORMATION
AND TECHNOLOGY ISLAMABAD
NETWORK PROGRAMMING
ASSIGNMENT # 1
SUBMITTED BY:
MUHAMMAD BILAL MUNIR
REG
FA08-BET-
SUBMITTED TO :
MA’AM MADIHA KAZMI
DATE: 10/10/
Q: Differentiate between OSI Model(Protocol) and Internet (tcp/IP)
Model (Protocol); and also write the names of atleast two protocols
used at each layer of both models?
OSI:
A: I f you spend much time in the company of network technicians you will eventually hear them say something like “That’s Layer 2 only” or “That’s our new Layer 4 switch”. The echnicians are referring to theOSI (Open System Interconnection) Reference Model. This model defines seven Layers that describe how applications running upon network-aware devices may communicate with each other. Themodel is generic and applies to all network types, not just TCP/IP, and all media types, not just Ethernet. It is for this reason that any network technician will glibly throw around the term“Layer 4” and expect to be nderstood. It should be noted, however, that most protocols in day-to-day use work on a slightly modified layer system. TCP/IP, for example, uses a 6- rather than a 7-layer model. evertheless, in order to ease the exchange of ideas, even those who only ever use TCP/IP will refer to the 7-layer model when discussing networking principles with peers from a different networking background. Confusingly, the OSI was a working group within the ISO (International Standards Organisation) and, therefore, many people refer to the model as the ISO 7-layer model. They are referring to the same thing. Traditionally, layer diagrams are drawn with Layer 1 at the bottom and Layer 7 at the top. The remainder of this article describes each layer, starting from the bottom, and explains some of the devices and protocols you might expect to find in your data centre operating at this layer. governed by a device’s MAC address, the six-byte number that is unique to each NIC. Devices which depend on this level include bridges and switches,which learnwhich segment’s devices are on by learning the MAC addresses of devices attached to various ports. This is how bridges are eventually able to segment off a large network, only forwarding packets between ports if two devices on separate segments need to communicate. Switches quickly learn a topology map of the network, and can thus switch packets between communicating devices very quickly. It is for this reason that migrating a device between different switch ports can cause the device to lose network connectivity for a while, until the switch, or bridge, re-ARPs
Protocols in each layer of OSI
Layer 1: Physical Layer
IEEE 802.
IEEE 802.15.4.
Layer 2: Data Link Layer
IEEE 802.
IEEE 802.
IEEE 802.
Layer 3: Network Layer
ITU-T Rec. X.213 [ISO/IEC 8348]
ITU-T Rec. X.233 [ISO/IEC 8473-
Layer 4: Transport Layer
ITU-T Rec. X.214 [ISO/IEC 8072]
ITU-T Rec. X.224 [ISO/IEC 8073]
Layer 5: Session Layer
ITU-T Rec. X.215 [ISO/IEC 8326]
ITU-T Rec. X.225 [ISO/IEC 8327-1]
Layer 6: Presentation Layer
ITU-T Rec. X.216 [ISO/IEC 8822]
ITU-T Rec. X.226 [ISO/IEC 8823-1]
Layer 7: Application Layer
ITU-T Rec. X.217 [ISO/IEC 8649]
ITU-T Rec. X.227 [ISO/IEC 8650-1]
The TCP/IP Protocol Suite:
The TCP/IP protocol suite, also referred to as the Internet protocol suite, is the set of communications protocols that implements the protocol stack on which the Internet and most commercial networks run. It is named after the two most important protocols in the suite: the Transmission Control Protocol (TCP) and the Internet Protocol (IP). The TCP/IP protocol suite—like the OSI reference model—is defined as a set of layers. Upper layers are logically closer to the user and deal with more abstract data, relying on lower layer protocols to translate data into forms that are transmitted physically over the network. TCP/IP Model and the OSI Reference Model The TCP/IP protocol suite was developed before the OSI reference model. As such, it does not directly map to the 7-layer OSI reference model. The TCP/IP protocol stack has only layers that can be loosely mapped to the OSI protocol stack
Application Layer
The application layer of the TCP/IP model corresponds to the application layer of the OSI reference model. Some well known examples of application level entities within the TCP/IP domain are:
- FTP/Telnet/SSH• HTTP/Secure HTTP (SHTTP)
- POP3/SMTP • SNMP
Transport Layer
The transport layer of the TCP/IP model maps fairly closely to the transport layer of the OSI model. Two commonly used transport layer entities are TCP and User Datagram Protocol (UDP) Internet Layer The Internet layer of the TCP/IP model maps to the network layer of the OSI model. Consequently, the Internet layer is sometimes referred to as the network layer. The primary component of the Internet layer is the Internet Protocol (IP).Many of the TCP/IP routing protocols are also classified as part of the Internet layer.
Network Access Layer
The lowest layer of the TCP/IP protocol stack is the network access layer. The network access layer contains two sublayers, the media access control (MAC) sublayer and the physical sublayer. The MAC sublayer aligns closely with the
Q2. Write a note on Drawbacks of Security systems e.g., firewall or
Intrusion Prevention Systems etc.,
FIREWALL :
The main drawbacks to Web application firewalls are cost and performance.
Performance is often an issue because these tools inspect all incoming and
outgoing traffic at the application layer. However, this level of examination,
often referred to as deep packet inspection, examines the actual payload of a
packet and provides far better content-filtering capabilities than traditional
packet-filtering firewalls. With application-layer firewalls, allow or deny
decisions can be based on the actual content of each packet. They can permit
or reject specific applications, or specific features of an application, giving a
greater degree of granular control. The firewalls can also authenticate users
directly.
Intrusion-prevention system
An intrusion prevention system is a computer security device that exercises access control to protect computers from exploitation. Intrusion prevention technology is considered by some to be an extension of intrusion detection (IDS) technology but it is actually another form of access control, like an application layer firewall. The latest Next Generation Firewalls leverage their existing deep packet inspection engine by sharing this functionality with an Intrusion-prevention system. The term "Intrusion Prevention System" was coined by Andrew Plato who was a technical writer and consultant for *NetworkICE.
The Disadvantages of Intrusion Detection Systems
o As companies continue to increase their use of the Internet for business uses, the occurrences of IT intrusions will increase. These intrusions are known as security breaches and result in the loss of proprietary information, if the breach is able to access sensitive company information. The installation of intrusion detection software is the first line of defense for most companies. While intrusion detection software can help with network security, there are a few disadvantages to the software.
Source Addresses
o Intrusion detection software provides information based on the network address that is associated with the IP packet that is sent into the network. This is beneficial if the network address contained in the IP packet is accurate. However, the address that is contained in the IP packet could be faked or scrambled. Either of these scenarios leaves the IT technician chasing ghosts and being unable to stop the intrusions to the network from taking place.
Encrypted Packets
o Encrypted packets are not processed by the intrusion detection software. Therefore, the encrypted packet can allow an intrusion to the network that is undiscovered until more significant network intrusions have occurred. Encrypted packets can also be set to be activated at a specific time or date once they have been planted into the network. This could release a virus or other software bug, which could be avoided if the intrusion detection software was able to process encrypted packets.