Network security protects computer systems and networks from hackers and mistakes. It involves designing secure network infrastructures, policies, and rules as well as continuously monitoring security measures. Files can be made publicly shareable or protected and shared only with authorized users as determined by file owners or network administrators. Firewalls filter incoming internet information to private networks using software or hardware, allowing only authorized traffic according to security policies. Digital signatures authenticate messages and documents by using a private key to sign them and a public key for verification.

1. NETWORK SECURITY

2. WHAT IS NETWORK
 Network: In simple language a computer network
is a collection of computers/devices also known as
nodes which are connected to each other in a
certain pattern and can communicate with each
other using some protocols

3. WHAT IS NETWORK SECURITY
 The Network security or Information security is to
provide protection to the computer system from the
Hackers.
 Network security protects the internal data from external
attacks or simple mistakes made by the user.
 It designs computer network infrastructure, policies and
rules adopted by the network administrator.
 It monitors consistently and continuously the effectiveness
of all the security measures.

4. FILE ACCESS PERMISSION
 In internet some files are made shareable and some are
made public.
 Protected files are shared among few users or by a group
having access right.
 Access right is decided by the owner of the file or network
administration.
 There are three types of users.
o Owner
o Users having access rights
o All other users

5. FIREWALL
 Firewall technology began to emerge in the late 1980s.
 A firewall is simply a program or a hardware device that filters the
information coming through the internet into your private network
or computer system.
 Security of the network is the main criteria of firewall.
 It can be implemented either in software or in hardware.
 Software firewall: These are installed on individual servers.
They intercepts each connection request and then
determines whether the request is valid or not.
 Hardware firewall: These are integrated into the routers that
sits between a computer and the internet.

6. GOALS OF FIREWALL
1. To collect the sum of all the network traffic internal or
external must go through the firewall physically. It cuts off
all the access to the local network except via firewall
2. Only authorized traffic which is acceptable by the local
security policy will be allowed to proceed
3. Firewall itself is resistant inclusive is a solid trustworthy
system with a protected security system

7. DIGITAL SIGNATURE
 A digital signature is a method for providing authenticity of a message
or document or attachment or software sent through email.
ADVANTAGES OF DIGITAL SIGNATURE
o It plays significant role in cases of cyber crime thus protect thus
security of a computer.
o Commonly used for software distribution, financial transaction and in
any other cases where forgery and tampering is possible.
o Gives recipient enough reason to believe that the message was
created by the known sender.

8. BASIC REQUIREMENTS OF DIGITAL
SIGNATURE
 Private key: it is which is accessible only to the signer.it
is used to generate the digital signature which is attached
to the message.
 Public key: the public key is made available to all those
who receive the signed message from the sender.it is used
for verification.