In this section we're going to look at virtual private networks all the peahens DPN solutions provide
for secure access across insecure medium such as the Internet allowing for the connection of branch
offices home offices business partners and remote telecommuters to all or some part of a corporate network.
The peons have become very popular because of low cost high bandwidth Internet connectivity which allows
for a secure encrypted connections back to central sites previously remote offices to connect to the
central office or head office three expensive leased lines or dial up phone lines.
The peons have helped reduce network costs by allowing for secure connections through broadband technology
such as DSL and cable these days.
The peons can transport mission critical data voice over IP and client server applications without compromising
quality or security.
In the section a look at an overview of the peahens at CCMA level they just expect you to have an appreciation
of VPN.
But in my experience I find people get really confused if you just gloss over some of the terms and
technologies and VPN components and thus I'm going to delve into it and a little bit more detail.
We're going to explain where the SEC is what encryption is what authentic nation is and what integrity
is.
All vital components in a VPN.
So again what is a VPN.
A VPN is an encrypted connection between private networks over a public network such as the Internet.
So it's a virtual private network which allows for the sending of traffic securely across an insecure
medium.
Thus you can say private data and private information across the Internet without the worry of someone
intercepting and reading your information to keep the data private.
The traffic is encrypted so that confidentiality is maintained.
Instead of using a dedicated connection between two sites such as a lease line we are using a public
infrastructure such as the Internet to send data securely from one private network.
Let's say a home network where he uses telecommuting to a central office or head office where the users
accessing for instance an Oracle database so secure data is sent between these two private sites across
the public Internet.
Now bit of history why the requirement will be paeans will provision for was created in the 1970s and
in those days network security wasn't a big issue.
It's important to realize that IP transmits a lot of data as text which is often referred to as transmitting
in the clear.
That is just transported in raw form with no encryption.
Lots of private information including usernames and passwords are think occasion information and other
private data is transmitted in clear text and if captured can easily be read by hackers and other individuals
Here's a simple example of a sniffer capture of a user logging into an empty server and you can clearly
see that the user name is anonymous.
Available in ted text and the password of Cisco is also shown in clear text.
So when you connect for instance to a web server the bet web server is not using encrypted HTP your
username and password for instance will be sent in clear text which is easy to capture and read all
information transmitted in an email.
For example I sent in clear text see some examples of critics protocols for instance if all the data
as well as the authentication information is to you a text if you're telling leading to a router or
a switch or you are syndication information is in clear text so usernames and passwords can easily be
captured as well as any commands that you type on the router or switch.
So as an example if you talk show run the entire running configuration could be captured.
There are some really powerful hacking tools available on the internet.
Please note I don't recommend you using them but just be aware that they exist.
An example would be Cain and Abel which is extremely powerful and can capture usernames and passwords
from multiple protocols including those listed here.
Just do a search for Cain and Abel in Google and you can see this Web site Oh excited dog I.T. provides
Cain and Abel for free.
And as really powerful features we're capturing and recovering passwords.
You use this program at your own risk.
And again I don't recommend that you use it but be aware that it exists.
It's empty since the contents of mail messages and text so just pop 3.
So does HTP.
So this is an MP version 1.
So be aware of the protocol that we use in everyday environments.
Same information in say a text which could be captured and read wine undesirables cryptography like
so many other things in life has its own terminology.
Some of the terms that you need to understand well firstly what an algorithm is an algorithm is detailed
steps for performing a function and a cipher is an example of an encryption algorithm.
We look at a lot of the algorithms in the next few slides but as an example days couple days and a yes
by encryption algorithms used for taking it takes data and putting it into non readable form for ciphertext.
In other words encrypted data.
The two main types of encryption algorithm that begin going to look at in this course the first one
is a symmetric algorithm the symmetric algorithm is where the same keys used encryption and decryption
and secret key algorithms like does triple days an alias or symmetric encryption algorithms an asymmetric
algorithm is an algorithm in which different keys are used for encryption and decryption public key
algorithms such as RSA or asymmetric encryption algorithms.
When can look at those in more detail in a moment but just be aware that with a symmetric algorithm
the same key is used to encrypt and decrypt with an asymmetric algorithm a different key is used to
encrypt versus decrypt.
So what is a key.
It is a bit of information that is required to decrypt the message.
Usually in the form of a value that is used with a cipher to encrypt the message it's important that
the key remain secret in order for the message to remain private.
Think of a key as a password a key or password is used with an encryption algorithm and together that
make the data secret Think of it as follows The algorithm is well known and can be read about in books.
You can look on Wikipedia there's lots of documentation explaining various algorithms like a stripper
does and does.
However the key is a secret valley a key use with an algorithm makes the data unique.
What are we trying to accomplish.
There are four things that you typically want to accomplish in a VPN.
The first one and the one most people think about is data confidentiality or encryption where no one
else should be able to read the information by manipulating the data that is sent across the public
infrastructure.
In other words if a hacker captures you information on the Internet that hackers should not be able
to decrypt or read the information data confidentiality is provided by using encryption algorithms with
the associated keys.
The second goal is data integrity and how we want to know that the data has traversed and changed between
the two parties.
For instance if party base in something to party B Party B wants to know that that data has not been
manipulated or changed in transit that data has arrived without changes as it was sent.
What party.
A The third goal is data origin authentication the Receive of the data needs to be able to verify that
the data that it received could only have originated from the sender.
In other words the so-called sender is the actual sender that we believe them to be the receiver wants
to be able to think teacake the source of the packet that arrived guarantying and certified who the
source of the information actually is.
And then the fourth goal is empty replay protection.
We want to verify that each packet is unique and is not duplicated.
So he has a very basic example of confidentiality for encryption and is one of the earliest forms of
encryption used by Seiza years and years ago if a hectic captured the following text.
M.J. Q-Q TE What does it mean.
Well two things have been done to this text.
The first is that an algorithm has been applied to see a text with a key.
So in this example the algorithm used is a so-called CS's algorithm where data has been moved to the
right hand side and the key space or key used is five.
Now if you reverse that process.
In other words move the letters by five to the left hand side.
This can be decrypted as hello just take an alphabet look at em for example move by five letters and
you'll get an H and so forth and so on.
So if a hacker captured the encrypted text he or she would have to know firstly which algorithm was
used and secondly what the key is once you know those two pieces of information.
It's just a matter of reversing the algorithm.
So there's a very simple example of data confidentiality encryption.
This is the process involved with encryption we reversely take some secret data which is encoded text.
This might be an order or a confidential email or some data that is in clear text that we want to keep
it confidential.
We then take a key in combination with an algorithm let's say abs or Advanced Encryption Standard.
I'll explain more about the algorithms in a moment.
But for now just understand that you take the original data which is in clear text.
We take a key you take the encryption algorithm the clear text when sent through the encryption algorithm
with a specific key results in ciphertext or encrypted data that encrypted data can then be sent across
a public infrastructure such as the Internet and a non desirable like a hacker will not be able to read
the information because it's encrypted the receiving party will receive encrypted data and will reverse
the process.
So in other words by applying the same algorithm and the same key but in the reverse direction the encrypted
data is reversed back to the original player it takes data and the receiving party can read the information.
So it's a simple process where you take the data you apply an encryption algorithm with a key to it
which results in ciphertext the sender then transmits that across an insecure medium such as the Internet.
The receiver reverses the process by applying the same key.
If it's a symmetric algorithm and the algorithm that reverses the process which results in the original
It takes data known algorithms keyspace or key length is a set of all possible values for that algorithm.
I find this confuses a lot of people some explain it by using an IP address and but Keys produces a
two to the n keyspace size.
So by looking at a Class A address as an example not provision for addresses 32 bits in size the network
portion is 8 bits and the host portion is 24 bits.
So two to the power of 24.
If you're over 16 and a half billion options or host addresses in theory.
So think about it as follows at 24.
But keyspace results in over 16 and a half billion combinations.
So keep that in mind when we look at the key spaces available in the various algorithms the greater
the keyspace the harder it's going to be to crack the encryption algorithm because there are more combinations
available.