Virtualização de serviços de rede - Cloud Computing

Virtualization and Network Services in Cloud Computing

Introduction to Virtualization

• The session focuses on virtualization and network services within cloud computing, specifically in Unit 2, Module 4.

• Virtualization allows the creation of virtual networks within a data center, which can contain tens of thousands of physical servers.

Understanding Virtual Networks

• A virtual network consists of multiple interconnected virtual machines (VMs) that can communicate exclusively with each other.

• Communication among VMs occurs without physical cabling or switches; it is established through software configurations.

IP Addressing in Virtual Networks

• Each virtual network operates within its own isolated IP address space, allowing for multiple clients across different networks.

• Private IP addresses are used for devices within a virtual network, ensuring isolation from other networks.

Subnetting and Routing

• Instances within a subnet can only communicate with each other unless routing is configured between subnets.

• Three blocks of private IP addresses are available:

• 10.0.0.0/8: Ranges from 10.0.0.1 to 10.255.255.254 (over 16 million combinations).

• 172.16.0.0/12: Ranges from 172.16.0.1 to 172.31.255.254 (about one million addresses).

• 192.168.x.x: Ranges from 192.168.1 to 192168255254 (around 65 thousand addresses).

Network Masking and Address Allocation

• Subnets are defined by a mask that indicates the size of the network; masks range from /32 (single address) to /0 (approximately four billion addresses).

• Example configuration shows how a /24 network can be divided into four subnets (/26), each containing up to 64 addresses.

Conclusion on Subnet Division

• The example illustrates dividing a single large subnet into smaller isolated subnets while maintaining efficient address allocation.

Configuring Communication Between Subnets

Understanding Subnet Communication

• The initial setup involves configuring permissions for communication between instances across different subnets, which is essential for network resilience.

• By default, instances within a subnet can only communicate internally; external communication requires specific routing configurations.

Creating Route Tables

• Two route tables are created to facilitate communication between two subnets. For example, Route Table 1 connects Subnet 2 and Subnet 3.

• An instance with an address in Subnet 2 (e.g., 10.0.0.70) can communicate with another instance in Subnet 3 (e.g., 10.0.0.140).

Establishing Additional Routes

• A second route table allows further connections, such as enabling an instance at address 10.0.0.500 in one subnet to communicate with another at address 10.0.0.210 in a different subnet.

• Instances in different subnets may not directly communicate unless routes are explicitly defined; transitively connecting through other subnets is generally not standard practice.

Routing Models and Permissions

• The routing model allows access from one entire subnet to another but may require additional routes for direct communications between specific addresses.

• Permissions can be broad or fine-tuned using Access Control Lists (ACLs), which filter IP packet traffic based on defined rules.

Security Policies: Firewalls and Access Control Lists

Overview of Security Mechanisms

• ACLs and firewalls are critical tools for defining security policies by filtering IP traffic based on set rules.

Firewall Rules Structure

• Firewalls typically consist of permission-only rules; if no rule exists, all traffic is denied by default.

• Firewall rules include both outbound (traffic leaving the instance) and inbound (traffic entering the instance), with strict controls on incoming traffic for security reasons.

Rule Evaluation Process

• Outbound rules generally allow all outgoing traffic unless specified otherwise, while inbound rules start off prohibitive—only allowing what is explicitly permitted.

Importance of Rule Order

• Rules are evaluated sequentially; thus, earlier deny rules take precedence over later allow rules, making the order crucial for effective policy enforcement.

Differences Between ACL and Firewall Rules

• Unlike firewalls that focus solely on permissions, ACL includes explicit permit and deny rules along with numbered priorities that dictate evaluation order.

This structured approach provides a comprehensive overview of configuring network communication and security policies within cloud environments based on the provided transcript content while ensuring clarity and accessibility through timestamps linked to relevant sections of the video transcript.

Access Control Lists and Network Security

Understanding Access Control Lists (ACLs)

• Access control lists are often built on Layer 3 information, specifically IP addresses. For instance, if a hacker's IP address is identified, a denial rule can be created to block that specific address.

• A key aspect of ACLs is that they only allow traffic if there is an explicit permit rule; otherwise, the traffic is denied by default. This means that without any rules allowing certain traffic, it will not pass through.

• ACLs examine only the incoming and outgoing traffic of a network or subnet but do not inspect internal communications between instances within the same subnet.

The Role of Name Resolution Services

• Name resolution services translate human-friendly domain names into numerical IP addresses. This abstraction helps users avoid dealing with complex numeric addresses when accessing websites like Google.

• In cloud computing environments, name resolution services are integral for managing how virtual networks communicate and ensuring user-friendliness in addressing.

Virtual Networks and Subnetting

• Virtual clouds can be structured into subnets which are isolated from one another. Communication between these subnets is controlled primarily through routing tables.

• The second level of control involves filtering policies set by firewalls. These policies define what types of traffic are permitted or denied for instances within the network.

Security Policies and Traffic Management

• Security policies dictate which types of traffic can flow between different instances in a network. These include both permit and deny rules established through access control lists (ACL).