1. Network interface(Data link) layer
2. Network layer
3. Transport layer
4. Application layer
Network interface layer
The lowest layer of the TCP/IP model. Its task is to provide access to the transmission physical medium and it differs according to the implementation of the medium.
Network layer
The network layer provides network addressing, routing and datagram transmission. Used protocols that will be of interest further regarding DHCP are IP and ARP.
IP protocol
It is the basic protocol of the network layer and in general the internet as a whole. It sends datagrams, which are independent units that contain information about the destination, source and the sequence number of the datagram. The sequence number is used for message reconstruction, since the delivery order of the datagrams might not be the same as their order in the message and delivery reliability isn't guaranteed at all.
IP protocol versions:
" IP v4 - 32 bit addresses. Provides approximately 4 billion unique addresses which aren't sufficient at present times.
" IP v6 - 128 bit addresses. The transition to v6 will bring (is bringing) higher security, QoS, packet segmentation and many more IP addresses. (the transition from IP v4 to IP v6 must be supported by the system provider)
ARP protocol
The ARP abbreviation stands for Address Resolution Protocol. This protocol is used to find the physical address (MAC) based on a known IP address. If required ARP sends information concerning the wanted address to all the stations in the network - Broadcast. The stations consequently answer with a message containing their MAC. If the wanted device/station is outside the node/segment, the appropriate router will answer instead of it.
Transport layer
The transport layer is implemented only in terminal devices and it adjusts the behavior of the network according to the requirements of the device/application.
Application layer
The application layer is composed of programs that use net services to fulfill the needs of users. Examples of specific protocols are for instance FTP, DNS and DHCP.
Application protocols use TCP, UDP or both services at the same time. So called ports are used to differentiate between application protocols, they represent a type of label of the application. It is possible to change the ports in the settings of the service, but each service has a default port that isn't changed for most services and is used as an unwritten standard.
" FTP = 21
" DNS = 53
" DHCP = 67 + 68
The traditional approach to implementing an intranet is to purchase a software package, modify it for your needs, and install it on your system.
Over the past few years, another option has grown in popularity – the implementation of a web-based solution.
As you consider the choice between installed software and a web-based intranet, here are some considerations:
1. The most important requirement of any intranet is that everyone uses it.
To assure broad-based participation, the intranet must be easy to implement, simple to use, cost-effective to maintain, and offer each individual user the power to post, access and use content in a way that serves their specific needs. In short, the intranet must have value to everyone.
Web-based intranets are designed around this concept. The interface and navigation are consistent with their use of the web – an environment in which they feel in control, using familiar tools.
In contrast, the business world is littered with countless elegant and feature-rich soft-ware based intranets that have failed. Why? Because they represented an alien environment into which the user was expected to venture. Few employees had the time or the interest (or courage) to enter, rendering the intranet impotent, with the powerful tools unused.
This is the plight of traditional, out-of-the-box software solutions. Unlike web-based intranets, they force users into a constrained environment requiring in-depth training, built around rules designed for the group, rather than the individual.
2. Software intranets have unpredictable costs: in time, attention and money.
Software based solutions require extensive internal support. The ongoing expense in both staff time and money takes the focus of your IT group away from mission-critical tasks.
System integration, Implementation, maintenance, technology upgrades, training and user support are all on-going tasks that represent a significant, recurring investment. The cost can be substantial, far exceeding your initial license cost and monthly fee.
3. Web-based intranets offer a predictable cost and cutting-edge technology.
Most web-based solutions offer a fixed monthly fee that covers all maintenance, technology upgrades, training and user support. The costs are predictable, the technology evolutionary, and it's all done with minimal involvement of your IT staff.
It's for these reasons that companies needing broad-based participation in a changing environment are choosing web-based intranets over traditional software solutions.
Over the past few years, another option has grown in popularity – the implementation of a web-based solution.
As you consider the choice between installed software and a web-based intranet, here are some considerations:
1. The most important requirement of any intranet is that everyone uses it.
To assure broad-based participation, the intranet must be easy to implement, simple to use, cost-effective to maintain, and offer each individual user the power to post, access and use content in a way that serves their specific needs. In short, the intranet must have value to everyone.
Web-based intranets are designed around this concept. The interface and navigation are consistent with their use of the web – an environment in which they feel in control, using familiar tools.
In contrast, the business world is littered with countless elegant and feature-rich soft-ware based intranets that have failed. Why? Because they represented an alien environment into which the user was expected to venture. Few employees had the time or the interest (or courage) to enter, rendering the intranet impotent, with the powerful tools unused.
This is the plight of traditional, out-of-the-box software solutions. Unlike web-based intranets, they force users into a constrained environment requiring in-depth training, built around rules designed for the group, rather than the individual.
2. Software intranets have unpredictable costs: in time, attention and money.
Software based solutions require extensive internal support. The ongoing expense in both staff time and money takes the focus of your IT group away from mission-critical tasks.
System integration, Implementation, maintenance, technology upgrades, training and user support are all on-going tasks that represent a significant, recurring investment. The cost can be substantial, far exceeding your initial license cost and monthly fee.
3. Web-based intranets offer a predictable cost and cutting-edge technology.
Most web-based solutions offer a fixed monthly fee that covers all maintenance, technology upgrades, training and user support. The costs are predictable, the technology evolutionary, and it's all done with minimal involvement of your IT staff.
It's for these reasons that companies needing broad-based participation in a changing environment are choosing web-based intranets over traditional software solutions.
You must have seen them. Web addresses like http://tinyurl.com/2gj2z3 which, when you click on them, take you to another web page. Why use them? Are there any risks in using them?
URL stands for Uniform Resource Locator. It's the posh technical term for a web address. Web addresses normally take the form http://www.somesite.com/somepage.html, which is not too much of a problem. But some site names can get very long, and so can page names. The increased use of database-driven sites mean that URLs can get very long indeed, and most of them is computer gobbledygook. They are impossible to type in, if you are reading them in a print article, and often get corrupted by word-wrapping when they appear in an email or blog posting.
An URL shortener is a web service that takes a long address that's hard to type, and turns it into a short one. You should use them in articles for print publication, classified ads, emails, blog and forum postings, anywhere there is a danger that the full address may be corrupted, or that someone may need to type the address into a browser manually.
But there is a danger in using short URLs that may make people afraid to use them. The short address disguises the real destination. This makes it easy for somebody to post an innocent looking message encouraging people to click on a link that takes them to a site which infects their computer with spyware, or something equally undesirable.
Some URL shortening services have tried to address this problem. The most well-known service, TinyURL.com, has an optional preview page that shows you the target address before you go there. But you have to know to type "preview" in front of the address, or visit the site and set it as a permanent option. Those who don't know about this are still vulnerable to deception.
A safe URL shortener would not allow the creation of links to undesirable sites. It would also always display a preview page, so the user always sees where the link is taking them before they go there. xaddr.com uses Internet blacklists to prevent its use to disguise sites that are advertised by spam. Its preview page offers a link to McAfee's Site Advisor, which can be used to check the safety of the destination.
Next time you need to write a long web address, use an URL shortener. But to encourage confidence that no harm will come from clicking the link, pick a safe one.
URL stands for Uniform Resource Locator. It's the posh technical term for a web address. Web addresses normally take the form http://www.somesite.com/somepage.html, which is not too much of a problem. But some site names can get very long, and so can page names. The increased use of database-driven sites mean that URLs can get very long indeed, and most of them is computer gobbledygook. They are impossible to type in, if you are reading them in a print article, and often get corrupted by word-wrapping when they appear in an email or blog posting.
An URL shortener is a web service that takes a long address that's hard to type, and turns it into a short one. You should use them in articles for print publication, classified ads, emails, blog and forum postings, anywhere there is a danger that the full address may be corrupted, or that someone may need to type the address into a browser manually.
But there is a danger in using short URLs that may make people afraid to use them. The short address disguises the real destination. This makes it easy for somebody to post an innocent looking message encouraging people to click on a link that takes them to a site which infects their computer with spyware, or something equally undesirable.
Some URL shortening services have tried to address this problem. The most well-known service, TinyURL.com, has an optional preview page that shows you the target address before you go there. But you have to know to type "preview" in front of the address, or visit the site and set it as a permanent option. Those who don't know about this are still vulnerable to deception.
A safe URL shortener would not allow the creation of links to undesirable sites. It would also always display a preview page, so the user always sees where the link is taking them before they go there. xaddr.com uses Internet blacklists to prevent its use to disguise sites that are advertised by spam. Its preview page offers a link to McAfee's Site Advisor, which can be used to check the safety of the destination.
Next time you need to write a long web address, use an URL shortener. But to encourage confidence that no harm will come from clicking the link, pick a safe one.
To the information security professional wireless networking may be thought of as a four letter word to be avoided at all costs. Regardless of the security implication wireless networking can provide cost efficiency, and because of that wireless technologies are here to stay. While many in the profession believe that wireless networks can be easily compromised, this class will show how the appropriate wireless architecture with the proper security controls can make your wireless network as secure as any other remote access point into your network.
In this three day, wireless security workshop, we will examine the cutting edge of wireless technologies. The purpose of the course is to give you a full understanding of what wireless (802.11) networks are, how they work, how people find them and exploit them, and how they can be secured. This hands-on course is based on real world examples, solutions, and deployments. In this course we will actually set up and use wireless networks, determine the tools to uncover wireless networks, and also look at how to defeat the attempts to secure wireless networks.
Course Completion
Upon the completion of our CISM course, students will have:
Constructed a wireless network architecture
Install and configure 802.1x authentication using Microsoft Windows IAS and Server 2000
Install a wireless access point
Distinguish between 802.11x standards
Defeat Wired Equivalent Privacy
Key Take Aways:
An understanding of wireless networks
A CD of common tools and documentation
An ability to search the internet for updates and more information on wireless networks
Detail of Course Content The following topics will be covered:
Wireless History
Radio Frequency (RF) Fundamentals
WLAN Infrastructure
802.11 Network Architecture
802.1X Authentication
Extensible Authentication Protocol (EAP)/(LEAP)/(PEAP)
Detection Platforms
WLAN Discovery Tools
Kismet
Wireless Sniffers
Conventional Detection
Antennas
Exploiting WLANs
Securing WLANs
Other Wireless Options
Legal Issues including GLBA and ISO-17799
Future
Resources
http://www.acquisitiondata.com/wireless_security.asp
In this three day, wireless security workshop, we will examine the cutting edge of wireless technologies. The purpose of the course is to give you a full understanding of what wireless (802.11) networks are, how they work, how people find them and exploit them, and how they can be secured. This hands-on course is based on real world examples, solutions, and deployments. In this course we will actually set up and use wireless networks, determine the tools to uncover wireless networks, and also look at how to defeat the attempts to secure wireless networks.
Course Completion
Upon the completion of our CISM course, students will have:
Constructed a wireless network architecture
Install and configure 802.1x authentication using Microsoft Windows IAS and Server 2000
Install a wireless access point
Distinguish between 802.11x standards
Defeat Wired Equivalent Privacy
Key Take Aways:
An understanding of wireless networks
A CD of common tools and documentation
An ability to search the internet for updates and more information on wireless networks
Detail of Course Content The following topics will be covered:
Wireless History
Radio Frequency (RF) Fundamentals
WLAN Infrastructure
802.11 Network Architecture
802.1X Authentication
Extensible Authentication Protocol (EAP)/(LEAP)/(PEAP)
Detection Platforms
WLAN Discovery Tools
Kismet
Wireless Sniffers
Conventional Detection
Antennas
Exploiting WLANs
Securing WLANs
Other Wireless Options
Legal Issues including GLBA and ISO-17799
Future
Resources
http://www.acquisitiondata.com/wireless_security.asp
The idea of reading email while lounging by the pool, text or instant messaging while doing the laundry, or lounging in the Jacuzzi listening to your MP3 collection is appealing to us all.
Unfortunately, many, or even most, wireless units don't come with security features already functioning. This may not seem like a big issue to someone who is simply setting up a home network, but there are a number of potential problems you should consider.
The most serious problem is the increase in identity theft. If your network is unsecured, the personal data on your wireless electronic equipment is also unsecured. The order you just placed for a book at Amazon may have given your contact and payment information to an unscrupulous hacker!
Nearly every town in which "WiFi" is common will have "War Drivers" and "War Chalkers" at work. These are people who walk or drive around town with wireless equipment, searching for unsecured networks. The "Chalkers" then live up their name, marking curbs and other public items with chalk so that others can more easily find and exploit your network.
Not all "War Drivers" are hackers, of course. Many just want to use your network for free, but the risk is high if you don't learn how to protect yourself. You can usually find quite a bit of free information as to how to secure your network at the website of your router's manufacturer, or by doing a search in a search engine for a phrase like "secure home wireless."
Beyond the truly malicious, there are also your neighbors who may find your network by accident and enjoy nosing into your activities and using your Internet access at will, slowing down your network speed in the process.
Even many businesses use cheap, home-use quality equipment for their company networks. With the poor security often found on small business networks, anyone with a basic knowledge of wireless can access sensitive company and customer data.
If you are unable to secure your network yourself, there are many service companies who will do it for you. A search of your local yellow pages or an inquiry at your neighborhood computer store should yield professional help and get your private data private again
Unfortunately, many, or even most, wireless units don't come with security features already functioning. This may not seem like a big issue to someone who is simply setting up a home network, but there are a number of potential problems you should consider.
The most serious problem is the increase in identity theft. If your network is unsecured, the personal data on your wireless electronic equipment is also unsecured. The order you just placed for a book at Amazon may have given your contact and payment information to an unscrupulous hacker!
Nearly every town in which "WiFi" is common will have "War Drivers" and "War Chalkers" at work. These are people who walk or drive around town with wireless equipment, searching for unsecured networks. The "Chalkers" then live up their name, marking curbs and other public items with chalk so that others can more easily find and exploit your network.
Not all "War Drivers" are hackers, of course. Many just want to use your network for free, but the risk is high if you don't learn how to protect yourself. You can usually find quite a bit of free information as to how to secure your network at the website of your router's manufacturer, or by doing a search in a search engine for a phrase like "secure home wireless."
Beyond the truly malicious, there are also your neighbors who may find your network by accident and enjoy nosing into your activities and using your Internet access at will, slowing down your network speed in the process.
Even many businesses use cheap, home-use quality equipment for their company networks. With the poor security often found on small business networks, anyone with a basic knowledge of wireless can access sensitive company and customer data.
If you are unable to secure your network yourself, there are many service companies who will do it for you. A search of your local yellow pages or an inquiry at your neighborhood computer store should yield professional help and get your private data private again
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