Networking Homework Help: Explain why security is important for WLANs, even more ...

Q)Explain why security is important for WLANs, even more so than for wired networks. 

Sol:

More security is needed and security is very much important in case of wireless LANs, when compared to wired LANs. The main reason behind this is in case of wireless LANs by making use of the wireless authentication of the authorized wireless user any one can make use of it also hacking the wireless network is very easy if it is not password protected. Since in most of the WLANs the users are not protected by a unique password, since wireless LANs are always used in case of places like college campus or office campus where multiple users can access the network. Hence in case of wired LAN there is a need for the dedicated channel or cable through which every user can get connected to the network whereas in case of wireless LANs there is no need for it, sometimes it will not even ask for any security passwords. Hence any user can get connected to the network and use it without paying for it. As a result more security is important for WLAN’s when compared to Wired LAN.

Networking Assignment Help: What specific steps can be taken to improve security in WLANs...

Q)What specific steps can be taken to improve security in WLANs?

Sol:

 The below steps can be taken to improve the security in WLANs:

a) Initially wireless network has to be authorized and authenticated.

b) Also all the users try to get connected to that particular has to be authorized and authenticated.

c) Every user connected to the network has to be uniquely identified by their own unique username and password.

d) Multiple users with same username and password should not be allowed to connect to the network.

e) Every user has to be properly disconnected so that no one in queue must be able to continue to get connected to the network with their username and password.

Think and Answer Assignments: Minicase IV Household Wireless page....

Q)Your sister is building a new two story house which measures 50 feet long by 30 feet wide and wants to network her family’s three computers together. She and her husband are both consultants and work out of their home in the evenings and a few days a month.  Each has a separate office with a computer, plus a laptop from the office that they occasionally use. The kids also have a computer in their playroom. They have several options for networking their home:

a) Wire the two offices and playroom with Ethernet cat5e and put in a 100Base-T switch.

b) Install one Wi-Fi access point ($85) and put Wi-Fi cards in the three computers (the laptops already have Wi-Fi)

c) Any combination of these options

There are many possible solutions to this problem.  What would you recommend, considering their current hardware configuration as well as potential expansion? Justify your recommendation.           

Sol:

The best possible solution is to go for installation of Wi-Fi access points followed by installation of Wi-Fi cards for the desktop computers. Anyways laptops will definitely have Wi-Fi inbuilt so there is no need for separate installation of the cards in laptops. The reason behind this is looking at the future definitely the desktops are getting replaced by laptops. Also laptops are portable, which means we can carry them any where we need but if they are connected to some network cables then we will not be able to access the network wherever we carry the laptops. Also in case of desktops if we place it in 1st floor but tomorrow we need it in the last floor then there is need to work on the network connectivity in it only labor is involved in shifting but network connectivity is always there since it is independent of the location within the office campus or two story house limits. Hence the recommendation here is to go for Wi-Fi connection.

Networking Homework Help: There is an ever growing range of physical media being offered such as fiber...

Q)There is an ever growing range of physical media being offered such as fiber, coax, satellite, IP over power lines, a number of wireless technologies, and more. Recently, the telephone companies announced 4G wireless communications and the IEEE has WiMax at Gigabit rates. What criteria would you use to select technologies for your business and for your home?

Sol:

The following are the criteria being used to select technologies for my business:

a) Multiple connections with maximum speed.

b) Higher bandwidth with lesser price.

c) Unlimited downloads with no additional charges.

d) Unlimited access within the coverage area irrespective of the machines being used.

e) Full time high speed networks without any congestion.

The following are the criteria being used to select technologies for my home:

a) Not more than two connections at a time.

b) Very lesser cost, irrespective of download limits.

c) Limited access but reduction in the monthly bill.

d) Moderate speed and bandwidth, irrespective of the congestion.

e) Lesser monthly rentals provided there are additional charges for download if it crosses the available limit.

Networking Assignment Help: Explain the RSA Public Key Encryption Scheme in detail...

Q)Explain the RSA Public Key Encryption Scheme in detail.In particular ,how do the encryption and decryption algorithms work? Explain also how you choose the public and private keys.Suppose a user picks n=17*5; i.e .,p=17 and q=5.How should he pick the public key and the private key (i.e., d and e)? Give the encryption and decryption algorithms.

Sol:

RSA Public Key Encryption which was invented by Cocks (GCHQ), independently, by Rivest, Shamir and Adleman (MIT). Say for example let ‘p’ and ‘q’ is the two large prime numbers.

Let N = p*q be the modulus, then Choose ‘e’ relatively prime to (p-1)*(q-1)

Find d such that e*d = 1 mod (p-1)*(q-1)

Here the Public key is given by (N, e) and the Private Key is given by ‘d’.

The encryption as well as the decryption algorithm works as follows:

To encrypt the message M compute

C = M^e mod N

And to decrypt the message C compute

M = C^d mod N

Please recall that e and N are public, hence if attacker can factor N, then he can definitely use ‘e’ to easily find the value of ‘d’ since e*d = 1 mod (p-1)*(q-1)

Factoring the modulus will break the RSA, therefore it is not known that whether the factoring is the only one way to break RSA.

Suppose a user picks N=17*5; i.e., p=17 and q=5.

Hence N= 85,

(P-1)*(q-1) = 16*4=64

Choose ‘e’ such that it is relatively prime to 64. Hence e=5

Find‘d’ such that e*d = 1 mod 64, we find that d = 7 works

Public key: (N, e) = (85, 5)

Private Key: d = 7

Encryption as well as decryption algorithm works as follows:

Public key: (N, e) = (85, 5)

Private Key: d = 7

Suppose message M = 8

Cipher text C is computed as

C = M^e mod N = 8⁵ = 32768 = 17 mod 85

Decrypt C to recover the message M by

M = C^d mod N = 17⁷ = 410,338,673

= 12,434,505 * 85 + 8 = 8 mod 85

Physics Homework: What current in the solenoid would be needed to produce a field of..

Q)
What current in the solenoid would be needed to produce a field of 1.5×10−3 T but in the opposite direction?

Sol:

From question 2, magnetic field of 1.6*10^-3, produces 2400 turns

Hence, magnetic field of 1.5*10^-3, produces 2250 turns

Magnetic field, B=u_o*n*I

Current, I = 1.5*10^-3/(4*pi*10^-7*2250)= 0.53A

Compare the telephone network & internet. List few similarities & differences.

1. A telephone network is a connection oriented circuit switched network. This means that a connection must be established between the two endpoints. Bandwidth is reserved for this circuit.

The Internet is a connectionless packet switched network. This means that packets can be sent without following an established connection and bandwidth can be shared with other users.

2. In a telephone network, there is a dedicated connection established between the two end users and it is a fixed line also the it has got a fixed monthly rental for the connection but call charges are extra based on the duration of the call and region(local or STD).

In case of Internet there is no dedicated connection but the all authorized users are connected to the network using a unique IP and the cost will be dependent on the data downloads being made. 

3. Telephone network can only give one to one connection only using a dedicated channel in the network.

Internet can have one-to-many connections through any channel which is free at that point of time.

4. In case of Telephone networks the billing is done based on the duration of the call and area of calling.

In case of internet the billing will be mainly on the usage of the data in bits per second.

5. The telephone network will be able to connect to internet network using a dial up connection and a dial up modem, but the data rate will be very low.

But in case of internet the connection is made to the network using a broadband modem and hence the data rate will be very high.

Prepare a 3-4 page paper comparing and contrasting five of the design patterns listed below!!!

Choose any five from the list:

1) Adapter

2) Data Access Objects
3)Facade

4)Observer
5)Proxy
6)Firewall

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Looking for the Answers on Networking question like SNMP based network management system??

Discuss how an SNMP-based network management system could be incorporated into such a network. Your answer should include details concerning the architecture of the network management system itself, and its various components, and a discussion about which types of devices should be ‘managed’, and why your answer should include samples of management queries sent to the managed devices and the associated responses returned by the devices. Also include configuration details where appropriate.

Comment on this post if you need the answer for this!!! 

Networking Assignment Help

Part 1

You are tasked with writing rule sets for two firewalls that protect your network and form a DMZ. All traffic from your internal network to the Internet passes through the DMZ. All servers that are accessible from the Internet reside inside the DMZ. All computers inside the network (internal network and DMZ) have private IP addresses. All traffic to and from the Internet passes through a NAT device which is located just inside the perimeter firewall. All computers on this network are Windows computers

Servers in the DMZ
Service Public IP Address Private IP Address Comments
HTTP/HTTPS 200.100.100.10 192.168.20.10
FTP 200.100.100.11 192.168.20.11
DNS 200.100.100.12 192.168.20.12 Uses TCP for zone transfers, services DNS lookup requests from all computers in the internal network and DMZ
Email 200.100.100.13 192.168.20.13 SMTP
Proxy 200.100.100.14 192.168.20.14 Not accessible from the Internet. Client computers connect to the proxy service on port 8080



Clients on the internal network: All user workstations access web sites via the Proxy server. There are three different internal subnets: 10.10.10.0/24, 10.20.20.0/24 and 10.30.30.0/24. Computers on the 10.10.10.0/24 subnet may access FTP servers on the Internet. Computers on the 10.20.20.0/24 network may access an SSH server on the Internet with the IP address 220.20.30.110. All computers on the internal network may access the company’s Email, DNS, FTP and web servers that reside in the DMZ.

Computers on the three internal subnets use dynamic NAT pools as follows when making connections to the internet.
Private IP address range NAT Pool
10.10.10.0/24 200.200.200.50 through 200.200.200.100
10.20.20.0/24 200.200.200.101 through 200.200.200.150
10.30.30.0/24 200.200.200.151 through 200.200.200.200


Answer the following:
(1)Write the two rule sets for the two firewalls that will allow only the traffic described to flow.



Part 3

You are tasked with implementing a rule set for a firewall. Internal computers are running Windows operating systems.

(3) In the following table create a rule set to implement the following requirements.
• Internal users are allowed to access web servers on the Internet (both HTTP and HTTPS) but do so via a proxy server that has an IP address of 192.168.20.5.
• Access to the following servers is not allowed:
a. www.riaa.com
b. www.mpaa.org
• Users are allowed to directly access an SSH server running at andromeda.cs.odu.edu
• Computers on the Internet should be allowed to connect to your email server (SMTP only) in order for your company to receive emails from other organizations. The IP address of the email server is 192.168.20.10.
• Your email server must be able to connect to other email servers on the Internet to forward outgoing email (SMTP only).
• All other traffic is not allowed

Rule
Number Protocol Source Address Source
Port Destination Address Destination
Port Direction Action





Part #4


You are tasked with implementing a rule set for two firewalls protecting your network in a DMZ configuration. Internal computers are running Windows operating systems.

(4)In the following table create a rule set to implement the following requirements.

Note:
NAT occurs just inside the perimeter firewall.



DMZ Servers
Purpose Private IP Public IP
Web proxy 192.168.10.10 150.150.150.10
FTP Proxy 192.168.10.11 150.150.150.11
DNS 192.168.10.20 150.150.150.20
Web server - public 192.168.10.30 150.150.150.30
Web server – corporate only 192.168.10.40 150.150.150.40
Email 192.168.10.50 150.150.150.50



Internal network servers
Purpose Private IP
Microsoft SQL Server Database 10.50.50.100

Requirements
Workstations
• User workstations are on the two subnets 10.10.10.0/24 and 10.20.20.0/24
• User workstations can access web servers on the Internet (http and https) but only via a proxy server which resides in the DMZ
• User workstations can access ftp servers on the Internet but only via an FTP proxy server which resides in the DMZ
• User workstations can access the DNS server which resides in the DMZ


DMZ Servers
• Web proxy may access web servers on the internet
• FTP proxy may access FTP servers on the internet
• DNS server will accept incoming requests from both internal workstations and from the Internet.
• DNS server will accept zone transfer requests from other name servers on the internet
• The public web server will accept requests from the internet only via HTTP
• The corporate web server will accept requests from the internet only via HTTPS
• The corporate web server will make connections to the internal Microsoft SQL Server database on its default port.
• The email server will accept SMTP requests from the internal network and the Internet. It will also make SMTP requests to other email servers on the Internet.

Internal Server
• The internal Microsoft SQL Server database server will accept incoming connections from the corporate web server in the DMZ

Rule
Number Protocol Source Address Source
Port Destination Address Destination
Port Direction Action
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