What is MAC address? How to Find or Locate MAC address?

MAC address

MAC address stands for Media Access Controller Address. 

MAC address is also called as hardware address or Ethernet address or physical address of a computer (end entities/devices in network capable of sending and receiving bits). 

MAC address is of 48 bit and it is represented in hexadecimal notation. These 48 bits are grouped into 6 part. each part contains 8 bit, which is called as octet. two octets are separated by either a colon (:) or by hyphen (-).

Each computer that is going to connect on network must have an ethernet card (NIC card) and MAC address assigned to that card. MAC address is assigned to NIC card by the manufacturer of NIC card. 

As earlier discussed earlier MAC address is of 48 bit (6 octet), in which 24 bit (first 3 octet) represent manufacturer ID and remaining 24 bits (remaining or last 3 octet) represent the serial number of card manufactured by manufacturer.

Example

1. 1A-2B-3C-4D-5E-6F
2. 9F:7E:5D:3C:1B:2A

In First MAC address '1A-2B-3C' is Manufacturer ID and '4D-5E-6F' Serial Number of NIC card.

MAC address is used to communicate over Data Link Layer. It is also used to communicate over Local Area Network or broadcast network.

If NIC card or Ethernet card is available in computer but driver software for it is not installed then it cant work. It cant show you Local Area Connection icon. It can not show MAC address of it. It cannot connect computer over network. To make NIC card usable, it is must to install driver software. After successful installation of driver, Local Area Connection icon is visible and MAC address can be located.

In this article I am going to show some steps which gives you How to Locate MAC address of Computer. MAC address can be located using different methods. here I am going to tell you two ways of locating MAC address.

Method 1 using command prompt.

First of all you have to open command prompt. There are different ways of opening command prompt. 

Following are ways of opening command prompt.
 

1. Click on start, then click on run (which opens run wizard) and type cmd and press enter
2. Press windows+r to get run wizard. Now type cmd and press enter.
3. Click on start and type command prompt, command prompt icon is displayed. click on command prompt.
4. Another way is to start --> all programs --> accessories --> command prompt.

Command Prompt

From above method you will get command prompt Next you have locate MAC address so again there are two commands.

First command is the getmac command. This command is used to get MAC address of your computer. So you just have to enter getmac into command prompt and press enter. Result of this command show you physical address and transport name. The field under physical address is your MAC address.

getmac command

getmac command result

Second command is the ipconfig. This command shows windows IP configuration details on command prompt. You just has to type ipconfig /all in command prompt and press enter. Result similar to following result will appear. the result contains windows IP configuration and Ethernet adapter Local Area Connection. Just find the field physical address which will show you MAC address of your computer.

ipconfig /all command result

Second Method

Another way is to locate MAC address is find icon of local area connection on taskbar and click on that. find Open Network and Sharing Center and click on that.

Network Sharing center will appear. Now find Local Area connection or go to change adapter setting and the go to Local Area Connection.

Network and Sharing Center

Now Local Area Connection Status will appear. Here find details and click on it to view details of Local Area Connection.

Local Area Connection Status

Now Local Area Connection details will appear in that find physical address will appear. In front of physical address there is MAC address of system.

Network Connection Details

 These are the ways to find MAC address of computer systems. MAC address can be located using command prompt or by using Ethernet adapter details.

NMA PST Question Bank

Network Management and Administration ( 17061) 

Progressive Skill Test Question Bank

Class CO5G

1. Define Topology and state the difference between star topology and mesh topology
2. Explain hub, bridge and router.
3. State advantages and disadvantages of networking.
4. What is IP address and subnet mask. Compare between IPv4 and IPv6.
5. List and explain steps for windows server installation.
6. Install, list and explain the different editions of server 2008.
7. Configure (domain controller) active directory domain services.
8. Create a user account in server 2008 and write down steps.
9. Create a group and add user to group in server 2008 and write down steps.
10. Create a folder and share folder in server 2008 and write down steps.
11. Install DHCP server on windows server 2008. And write down its steps.
12. Define wireless network. Give comparison between wired and wireless network. Also explain Ad-hoc network.
13. Understand the networking available in laboratory and write hardware, software specification.
14. Define Network. What are types of network?
15. Give difference between client server and peer to peer network.
16. What is MAC address? How to locate MAC address of computer?
17. Assign and write down the procedure for assigning IP address and TCP/IP configuration settings.
18. What are types of transmission media? Which transmission media is used in your Lab, give its specification.
19. Explain cloud computing. Also explain the services provided by cloud.
20. What is backup? How to take backup?

Computer Security (CSE 17514) Practice Test 3 Model Answer

Computer Security (CSE 17514) Practice Test 3 (100 Marks) Model Answer

Computer Security CSE 17514 Practice Test 2 Model Answer

Computer Security (CSE 17514) Practice Test (100 Marks) II Model Answer

Computer Security (CSE 17514) Practice Test Model Answer

Computer Security (CSE 17514) Practice Test 100 Marks Model Answer 

Switch

Switch 

Switch is a network control (or network connecting/ network equipment) device. It is the device which is used to interconnect computers, workstations, servers and other networking devices to form IT network. It connects communicating devices using separate cables. One end of the cable is connected to communicating device and other end is connected to switch. So it provides a central point of connections for cables from other devices to create network (LAN). It is also used to connect two or more LANs (multiple LANs) to facilitate network.

Switch operates at Physical layer as well as Data Link Layer of OSI model. It handles network data which is in the form of frame.  

Switch looks like Hub, it is also used to connect all devices on a network so that they can communicate with each other. But switch and hub has some functional differences in hub and switch. When data comes at one port of hub, it duplicate that data and send on all other ports except the received port. It means Hub broadcast data to each and every connected node.

But switch is the intelligence device which can learn MAC addresses and forward packet to exact destination. Switch maintains record in switching table. The switch table record contains the MAC addresses and physical port providing access connection to system which MAC is recorded.

Initially switching table is blank, there is no entry of MAC address and physical port number. Record is inserted when switch is power on and connected nodes start communicating. 

First time when a frame is received on switch (when switching table is blank) switch retrieves the source and destination MAC addresses which are contained within frame. Switch learn the MAC address and make entry in table about the source systems MAC address and connected port. But switch don't know the destination system is connected to which port, it will do flooding. Means it will send the incoming frame on all other port, in short it broadcast the frame. In this fashion switch learn MAC addresses and from second time onwards it will do unicast. Means it will send the received frame to appropriate port which give access to destination.

Switches are similar to bridges in that both route on frame addresses. The main difference is that a switch is most often used to connect individual computers and bridge is used to connect LAN segments.

Switch provides bridging functionality with greater efficiency. It acts as a multi port bridge to connect network devices or segments in LAN.

Switches are capable of inspecting incoming data packets, determine source and destination of device of each packet and forward them appropriately.

Since each switch port usually goes to a single computer, switches must have space for many more line cards than do bridges intended to connect only LANs. Each line card provides buffer space for frames arriving on its ports. Since each port is its own collision domain, switches never lose frames to collisions. However, if frames come in faster than they can be retransmitted, the switch may run out of buffer space and have to start discarding frames.

Most switches are active, that is they electrically amplify the signal as it moves from one device to another.

Switches are usually configured with 8 port, 12 port, or 24 port and come with RJ-45 port interface

Switches are often used in implementation of star or tree topology.

Switch is also called as layer 2 device which means that the device that operates at layer 2 (Physical Layer and Data Link Layer) of OSI model.

There are two types of switches that are Layer 2 switch and Layer 3 switch. Layer-2 devices build hardware address tables, which will contain minimum two things. One is Hardware addresses (Physical address or MAC address) of host devices which are connected to switch. Second The port to which hardware address is associated

Using this above information, Layer-2 devices will make intelligent forwarding decisions based on contents and context of frame (Data-Link Layer) headers.

A frame can then be forwarded out only the appropriate destination port which gives access to destination, instead of all ports. There is one to one (unicast) communication possible using switch instead one to many (broadcast).

Layer-2 forwarding was originally referred to as bridging. Bridging is a largely deprecated term (mostly for marketing purposes), and Layer-2 forwarding is now commonly referred to as switching.

There are few technological differences in between switching and bridging. Remarkable difference is switches usually have more ports as compare to bridge (switches having a higher port-density), and second difference is, switches can make forwarding decisions at very high speed (wire speed). Switches use specialized hardware circuits to make forwarding decision faster, these hardware circuits called as ASICs (Application-Specific Integrated Circuits). Otherwise, bridges and switches are nearly identical in function.

Ethernet switches build MAC-address tables through a dynamic learning process. A switch behaves much like a hub when first powered on. The switch will flood every frame, including unicasts, out every port but the originating port. The switch will then build the MAC-address table by examining the source MAC address of each frame. Switches always learn from the source MAC address.

However, as the MAC-address table becomes populated, the flooding of frames will decrease, allowing the switch to perform more efficient forwarding decisions.

While hubs were limited to half-duplex communication, switches can operate in full duplex. Each individual port on a switch belongs to its own collision domain. Thus, switches create more collision domains, which results in fewer collisions.

Like hubs though, switches belong to only one broadcast domain. A Layer-2 switch will forward both broadcasts and multicasts out every port but the originating port. Only Layer-3 devices separate broadcast domains.

Because of this, Layer-2 switches are poorly suited for large, scalable networks. The Layer-2 header provides no mechanism to differentiate one network from another, only one host from another. This poses significant difficulties. If only hardware addressing existed, all devices would technically be on the same network.

There are three things that switches do that hubs do not that includes first is Hardware address learning, second Intelligent forwarding of frames and third is Loop avoidance.

 

Layer-2 Forwarding Methods

Switches support three methods of forwarding frames. Each method copies all or part of the frame into memory, providing different levels of latency and reliability. Latency is delay - less latency results in quicker forwarding.

The Store-and-Forward method copies the entire frame into memory, and performs a Cycle Redundancy Check (CRC) to completely ensure the integrity of the frame. However, this level of error-checking introduces the highest latency of any of the switching methods.

The Cut-Through (Real Time) method copies only enough of a frame’s header to determine its destination address. This is generally the first 6 bytes following the preamble. This method allows frames to be transferred at wire speed, and has the least latency of any of the three methods. No error checking is attempted when using the cut-through method.

The Fragment-Free (Modified Cut-Through) method copies only the first 64 bytes of a frame for error-checking purposes. Most collisions or corruption occur in the first 64 bytes of a frame.

Network Equipment Manufacturers 

• Cisco
• Juniper
• Dlink
• Digisol
• Netgear

Bridge Networking Device

Bridge

Bridge is a network device which divides a big network into smaller sub networks called segments. These segments are not consider as a separate network. Rather two segments can acts as a part of a single network because of bridge.

Bridges operates at both layers of OSI reference model that are physical layer as well as data link layer. Bridge is intelligence device which takes decision whether to forward the incoming frame on other port or discard it. It can also learn physical address of connected hosts and maintain this record in table called as forwarding table.

A bridge is basically a simplified two-port switch connecting two network segments. It does not have VLAN functions.

When bridge receives traffic on its any port, it checks incoming traffic and decides whether to forward or discard it. This decision is based on MAC address and forwarding table. the forwarding table is used by bridge while making filtering decisions.

Bridge know the physical address (MAC address) of all stations connected to it by listening network. Most of the bridges have capabilities to listen network automatically. Some other bridges don't have automatic learning capability, so in that case user or administrator has to manually add MAC address entries of connected hosts in bridging table for making decision.

Bridge checks incoming frame on a specific port connecting network segment, it then reads the physical address of destination host contained in the frame and the compares address with a forwarding table.

When it finds a match. It discovers segment to which destination station belongs and it needs to sends the frame only to that segment. So the bridge simply forward the frame on particular port to which the destination host connected to segment.

If source and destination both remain on same segment then bridge does not forward the frame. If source and destination are on different segment then bridge has to forward frame to segment to which destination is connected.

If the recipient’s MAC address is not in the list, then the  bridge blocks the data from passing. Bridge can connect different network architecture like token ring and Ethernet.

Bridge Forwarding Table

Physical Address	Port Number
1A-2B-3C-4D-5E-6F	1
4B-3D-7F-2C-6F-A6	2
4D-5E-6F1A-2B-3C	1
3C-4D-1A-2B-5E-6F	2

Forwarding table shows that the hosts that are connected to port number 1 and 2 of bridge. All the systems connected to port 1 are part of one  segment and systems connected to port 2 are part of another segment.

Types of Bridge

1. Simple Bridge
2. Multi port Bridge
3. Source route bridge
4. Translation Bridge
5. Local Bridge
6. Remote Bridge

1. Simple Bridge

Simple bridge are most primitive & less expensive bridge. Simple bridge cannot learn physical address automatically. The user has to enter the address manually in the forwarding table.

Whenever a new station is connected its physical address must be added to forwarding table. If station is disconnected or removed, then its address entry must be deleted from the forwarding table. So the table must be modified to have proper communication.

The simple bridge links only LAN segments.

2. Multi port Bridge

The bridge must have minimum two port in order to connect two segments. To connect multiple segments of LAN, the bridge should have more than 2 ports. The multi port bridge is the bridge is used to connect more than two segments.

3. Source route bridge

The source of each packet defines the bridge and LANs through which the packet should go before reaching destination. Frame contains different addresses like source, destination and bridge address. The station do majority of work here. Bridges do not filter broadcast packets and collisions are not transferred. Source route bridge avoids looping problem, it is designed for token ring

4. Translation Bridge

Translation bridge is used to connects network segment running at different speed or using different protocols.

5. Local Bridge

Local Bridge is used to connect network segments of same type and same location.

6. Remote Bridge

Remote bridge is designed to connect two network segments at distant location using WAN link.

Bridge advantages

Bridge is self configuring device.
It is used to interconnect two LANs.
It can minimize traffic on a segment.
It filter traffic and increases throughout on a network.
Primitive bridges often inexpensive.
It isolate a busy network from a not so busy one

Bridge disadvantages

It is slower than repeater and hub.
It is more expensive than repeater.
Does not scale to extremely large network.
It gives an error in bridging of different MAC protocol.
Does not limit the scope of broadcasts.

Digital Subscriber Line

Digital Subscriber Line

As Internet access became widespread and increasingly important part of business, the telephone companies (the platform for internet connection) realize that they need to have a more competitive product. 

The telephone companies got solution is to start new digital services, offering over the local loop. They aim to provide Services with more bandwidth than standard telephone service (broadband).

A digital subscriber line (DSL) connection is a high-speed network connection. DSL connection is done by using the same wires as a regular telephone line. 

DSL provides dedicated point-to-point network access services. DSL service is provided using copper wire that is twisted-pair cable. The connection loop between a network service provider's central office and the customer.

DSL modems are connected to Digital Subscriber Line Access Multiplexer (DSLAM) through DSL circuits.

It creats three data channels: a high-speed downstream channel, a low-speed upstream channel, and a basic telephone service channel.

The DSLAM (the cloud) provides one of the main differences between DSL and cable modems.

Because cable-modem users generally share a network loop that runs through a neighborhood, adding users means lowering performance in many instances.

Asymmetric Digital Subscriber Line (ADSL) provides a dedicated connection from each user to the DSLAM. Therefore, users won't see a performance decrease as new users are added.

Customer premises must contain Network Interface device which is connected to DSL connection. The Network Interface device is closely connected to splitter, which separates channels (band).

A DSL Modem can be used to connect to a modem port defined in the Cloud using telephone wire.

Another device (such as a PC or a router) is connected to Ethernet port on the DSL Modem.

The DSL Modem acts like a bridge forwarding traffic from one port to the other port.

Assignment No. 6

Computer Security Assignment No. 6

1. Explain web servers and active directory
2. Describe secure electronic transactions
3. Describe SSL protocol stack with sketch
4. Explain the term hotfix, patches and upgrades
5. What are SET requirement?
6. List and explain SET participants 
7. Explain different threats to web security
8. Explain Web Traffic Security approaches 
9. Explain SSL handshake protocol

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Assignment No 5

Computer Security Assignment No. 5

1. What is data recovery?
2. How to recover formatted partition?
3. What is cybercrime?    
4. Describe hacking and cracking
5. Explain the term software piracy
6. Explain intellectual property with copyright and patent
7. List steps for investigating cyber crime
8. What are objectives of IT Act 2000
9. What are characteristics of IT Act 2008

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Assignment No. 4

Computer Security Assignment No. 4

1. Explain the working of host based intrusion detection system
2. Explain the working of network based intrusion detection system
3. What is IP security? Explain authentication mode of IPSec
4. Describe the working of PEM mail security
5. How PGP is used for email system.
6. Explain Kerberos
7. Explain packet filter firewall with diagram
8. Explain tunnel and transport mode of IPSec
9. Explain Virtual private network
10. Explain Virtual LAN
11. What is firewall? What are its design principles and limitations?
12. What is security topology? Describe security zones in detail
13. What is firewall? List different types of firewall
14. Describe the term honeypot

Computer Security CSE 17514 MSBTE Winter 2014 Model Answer

Computer Security CSE 17514 MSBTE Summer 2015 Model Answer

Computer Security 17514 Question Bank

1. List and explain key principles of computer security

2. Describe the term authentication and explain its methods

3. Define Virus and explain phases of virus

4. Compare between virus and worm

5. Explain the term

            i. Sniffing

            ii. Replay Attack

            iii. Ping of Death attack

6. Explain active attack and passive attack with suitable diagram

7. Define spoofing and Explain IP spoofing in detail.

8. Explain SYN flooding attack in detail.

9. List and explain types of viruses

10. Explain password selection criteria with suitable example.

11. Explain Piggybacking and shoulder surfing

12. Explain Dumpster diving and how it is avoided.

13. State four problems due to installation of unauthorized s/w

14. Which are the individual user responsibilities in security?

15. Define access control. Explain access control types.

16. Explain Bio-metric system with suitable diagram.

17. Define

            i. Cryptography

            ii. Encryption

            iii. Secret key

            iv. Ciphertext

            v. Cryptology

            vi. Cryptanalysis

            vii. Decryption.

18. Encrypt "COME HOME TOMORROW" using Caesar's cipher with key 5

19. Convert the "Welcome to Computer World" using Rail Fence technique

20. Encrypt "Meet Me after party" using simple columnar transposition technique with key 4,6,1,2,5,3