Email - Computer - Files and Internet Security

Internet security is a branch of computer security specifically related to the Internet. It's objective is to establish rules and measure to use against attacks over the Internet. The Internet represents an insecure channel for exchanging information leading to a high risk of intrusion or fraud (e.g. phishing).[2] Different methods have been used to protect the transfer of data, including encryption.  Network layer security: Transmission ControlProtocol/Internet Protocol (TCP/IP) can be made secure with the help of cryptography. Cryptographic methods and protocols have been developed for different purposes in securing communications on the internet. These protocols include SSL and TLS for web traffic, PGP for email, and IPsec for the network layer security.

Electronic mail security (E-mail): Understanding of how email messages are composed, delivered, and stored is helpful in understanding email security. The process starts with message composition. When the user finishes composing the message and sends the message, the message is then transformed into a specific standard format specified by Request for Comments, Internet Message Format. Once the message is translated into formatted message, it is then transmitted to the receiver. Using a network connection, the mail client connects to a mail transfer agent operating on the mail server. After initiating communication with the mail server, the mail client provides the sender’s identity to the server. Next, using the mail server commands, the client tells the server who are the intended recipients. After the complete recipient list is sent to the server the client supplies the message. Once the mail server is processing the message, several events occur: recipient server identification, connection establishment, and message transmission. Using Domain Name System (DNS) services, the sender’s mail server determines the mail server(s) for the recipient(s). Then, the server opens up a connection(s) to the recipient mail server(s) and sends the message employing a process similar to that used by the originating client. Finally the message is delivered to the recipient.

Role of Firewalls in Internet Security: Firewalls impose restrictions on incoming and outgoing packets to and from private network. All the traffic whether incoming or outgoing must pass through the firewall, but only authorized traffic is allowed. Firewalls create checkpoints between an internal private network public internet. They are also called choke points. Firewalls can create choke points based on IP source, and TCP port number. They can also serve as the platform for IPsec. Using tunnel mode capability, firewall can be used to implement VPNs. Firewalls can also limit network exposure by hiding the internal network system and information from public internet.