1. IPSec – Internet Protocol Security: IPSec is

ARP – Address
Resolution Protocol: The Address Resolution protocol exists in the Data-Link
Layer of the OSI Model and is used by IPv4. It is used to determine the MAC
(Media Access Control) address of a machine when given the IP address. The
computer that wants to send information broadcasts an ARP request which
contains information about the sender’s IP Address and MAC Address, and the
destination computer’s IP Address. The destination will then know what MAC
Address is associated with the sender’s IP Address, and will add this to its ARP
table. It will respond with an ARP reply, where it sends back its IP Address
and MAC address. The original sender will then add this information to it’s ARP
table, at which point both computers have all they need to communicate. If the
destination computer exists on the sender’s subnet, the sender will send
information directly to the machine. If it exists on the open internet, it will
send information to the MAC Address of the router.






IPv6 –
Internet Protocol Version Six: IPv6 is the replacement for IPv4. It solves the
problem of not having enough Internet Protocol addresses for all machines. The
internet was launched in 1983 and contained 4.3 billion addresses, which at the
time seemed like more than enough. However, with the advent of mobile internet
technology, if each device had an IPv4 address, all addresses would quickly be
exhausted. IPv6 was designed in 1996 and has 128 bits of address space.
Therefore, 3.4 x 1038 unique IP addresses can be assigned to
devices. If the tech world continued with IPv4, people would eventually not be
able to access the internet as they would not have addresses, and the internet
would cease to grow. IPv6, like IPv4, exists in the Network Layer of the OSI





IPSec –
Internet Protocol Security: IPSec is used to secure communication over
networks. The original Internet Protocol could not guarantee the authenticity, privacy,
or confidentiality of data sent through a network. Previous to IPSec, security
measures were implemented at the application layer. This was not a practical,
as such an approach was not general enough and security had to be tailored for
specific applications. IPSec exists at the Network Layer of the OSI Model and allows
one to trust the sender of data by verifying the claim that the sender is the
true sender, ensures that the data has not been manipulated in any way, and
also that the data was not viewed during transit. IPSec encrypts the traffic
between two end points. IPSec works in Transport Mode, which encrypts only the
payload, and Tunnel Mode, which encrypts the entire IP packet.





BGP – Border
Gateway Protocol: BGP is an IP Routing Protocol. It advertises reachability
information between systems. A system tells others that are directly connected
to it which IP Addresses it can reach. Those systems receive that information,
along with information about the original sender. These systems then advertise
that information to other systems they are directly connected to. Those systems
now know the 2nd to original sender. This gives each system options
on routes to send data through to one of the IP Addresses listed. BGP allows
systems to know which hops are possible, so that they can choose the most
efficient route. BGP exists at the Network Layer in the OSI Model.





UDP – User
Datagram Protocol: The UDP protocol exists in the Transport Layer
of the OSI Model and is used to create connections between Internet
applications. It is an alternative to TCP (Transmission Control Protocol). UDP
is faster, however less reliable. This is because UDP is only 8 bytes in size,
compared to TCP which is 24 bytes. Also, TCP has more overhead because of error
correction, etc., which make it more reliable, but this also slows it down. UDP
is used mainly for live video or audio streams, or VoIP. It excels in
delivering real time data.




POP3 – Post
Office Protocol version 3: POP3 is a protocol for downloading and storing
e-mails using TCP/IP. Once mail is downloaded from the server onto the local
machine, it can be viewed even while offline. A disadvantage is that after being
downloaded, the mail is removed from the server. IMAP (Internet Message Access
Protocol) has an advantage over POP3 in that it allows a user to check their
email from multiple locations. POP3 resides in the Application Layer of the OSI




HTTPS – Hyper
Text Transfer Protocol Secure: HTTPS is HTTP with a layer of SSL or TLS over
top of it. SSL stands for Secure Sockets Layer while TLS stands for Transport
Layer Security. It exists at the Application Layer of the OSI Model. HTTPS is a
secure version of HTTP; it encrypts communication between a client and a server
using public key infrastructure. The server uses a private key to decrypt the
data sent by the client, and the client uses a public key to encrypt the data
in this asymmetric infrastructure. Eavesdropping on communication is still
possible even when using HTTPS, but an attacker would not be able to decrypt
the intercepted data without the server’s private key. This helps to guarantee
server identity and data privacy.





DHCP – Dynamic
Host Configuration Protocol: DHCP automatically assigns IP Addresses to
clients, ensuring that no two clients have the same address which would cause
an IP Conflict. It exists in the Application Layer of the OSI Model. For DHCP
to work, machines on the network must run a DHCP client, and the network must
have a DHCP server. When a new client attempts to join a network, it finds the
DHCP server by broadcasting to all machines on the network. The DHCP server replies
by offering an IP Address to all machines on the network, because it does not know
where the requesting client is as its IP Address is not assigned yet. The client
will then reply by broadcasting to all machines on the network that it accepts the
IP Address given by the DHCP server. This is a DHCP ACK, DHCP acknowledgement. The
DHCP Server then broadcasts to all machines that the client can go ahead and use
that address for a certain amount of time. The time limit is used so that IP Addresses
can be recycled.




Installing and Configuring DHCP


SLIP – Serial Line
Internet Protocol: SLIP generates a character sequence that organizes IP packets
on a serial line. It does little else, which makes it easy to implement. It is outdated
and replaced by PPP (Point to Point Protocol), and is used to connect machines across
a modem line or cable connection. It is a protocol found at the Data-Link Layer
of the OSI Model





10.  ICMP – Internet
Control Message Protocol: ICMP protocol sends control messages that relay
information about problems in communication, errors reports, and hop routing. It
exists in the Transport Layer of the OSI Model. The ICMP header is composied of
Type, which is 8 bits, Code which is 8 bits, a checksum of 16 bits, and a variable
length of data. ICMP follows the MAC Header and IP Header of a packet.