Many network security threats today are spread over the Internet. The most common include:
Viruses, worms, and Trojan horses
Spyware and adware
Zero-day attacks, also called zero-hour attacks
Hacker attacks
Denial of service attacks
Data interception and theft
Identity theft
There are several to avoid the above mentioned issues, such as:
1) Via MD5 which is an algorithm that is used to verify data integrity through the creation of a 128-bit message digest from data input (which may be a message of any length) that is claimed to be as unique to that specific data as a fingerprint is to the specific individual.2 Due its vulnerability it is not really recommended to use MD5 anymore, instead of it SHA-256 algorithm is suggested.
2) Via firewall which is a system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.3
3) Via access control list which is a set of data that informs a computer's operating system which permissions, or access rights, that each