Networking Recap - eJPTv2
eJPTv2 Training Notes.
1. Introduction to IP and MAC Addresses
IP Addresses
- IPv4 Address: 32-bit number, written in decimal format as four octets separated by periods (e.g.,
192.168.1.1). - IPv6 Address: 128-bit number, written in hexadecimal format, separated by colons (e.g.,
2001:0db8:85a3:0000:0000:8a2e:0370:7334).
Types of IP Communication:
- Unicast: One-to-one communication.
- Multicast: One-to-many communication within a specified group.
- Broadcast: One-to-all communication within a network segment.
MAC Addresses
- Unique 48-bit identifier assigned to network interfaces for communications at the data link layer.
- Format: Six pairs of hexadecimal digits, separated by colons or hyphens (e.g.,
00:1A:2B:3C:4D:5E).
IP vs. MAC Addresses
- IP Address: Used for logical addressing and routing.
- MAC Address: Used for physical addressing within a local network.
2. Classes of IP Addresses
Class A
- Range:
1.0.0.0to126.0.0.0 - Default Subnet Mask:
255.0.0.0(/8) - Hosts per Network: 16,777,214
- Private Range:
10.0.0.0to10.255.255.255
Class B
- Range:
128.0.0.0to191.255.0.0 - Default Subnet Mask:
255.255.0.0(/16) - Hosts per Network: 65,534
- Private Range:
172.16.0.0to172.31.255.255
Class C
- Range:
192.0.0.0to223.255.255.0 - Default Subnet Mask:
255.255.255.0(/24) - Hosts per Network: 254
- Private Range:
192.168.0.0to192.168.255.255
Class D (Multicast)
- Range:
224.0.0.0to239.255.255.255
Class E (Experimental)
- Range:
240.0.0.0to255.255.255.255
3. Private and Public IP Addresses
Private IP Addresses
- Used for internal network communication, not routable on the public internet.
- Ranges:
- Class A:
10.0.0.0to10.255.255.255 - Class B:
172.16.0.0to172.31.255.255 - Class C:
192.168.0.0to192.168.255.255
- Class A:
Public IP Addresses
- Routable on the public internet, globally unique.
- Assigned by IANA and regional internet registries.
4. CIDR Notation
CIDR (Classless Inter-Domain Routing)
- Allows for more flexible IP address allocation and routing.
- Notation:
IP address/prefix length(e.g.,192.168.1.0/24).
Examples:
- /24: 255.255.255.0 (256 addresses)
- /12: 255.240.0.0 (1,048,576 addresses)
- /16: 255.255.0.0 (65,536 addresses)
5. Subnetting
Concept of Subnetting
- Divides a large network into smaller sub-networks.
- Improves IP address allocation, network performance, and security.
Subnet Mask
- /24: 255.255.255.0
- /16: 255.255.0.0
- /12: 255.240.0.0
Benefits of Subnetting
- Efficient IP Address Allocation: Reduces IP address waste.
- Improved Performance: Limits broadcast traffic to subnets.
- Enhanced Security: Isolates network segments.
- Simplified Management: Easier network management.
6. Subnetting Example
University Network Example
- Network:
192.168.1.0/24 - Subnets:
- Subnet 1:
192.168.1.0/26(64 IPs) - Subnet 2:
192.168.1.64/26(64 IPs) - Subnet 3:
192.168.1.128/26(64 IPs) - Subnet 4:
192.168.1.192/26(64 IPs)
- Subnet 1:
7. Subnetting in Penetration Testing
Enumeration
- Network Mapping: Identifying subnets helps map network structure.
- Host Discovery: Targeting specific subnets reveals live hosts.
Penetration Testing
- Scope Definition: Defines the scope of the test.
- Segmentation Testing: Assesses network segmentation security.
- Traffic Analysis: Monitors traffic within and between subnets.
- Target Identification: Focuses on high-value targets in specific subnets.
Summary
- IP Addresses: Logical addresses for network communication.
- MAC Addresses: Physical addresses for local network communication.
- IP Classes: Class A, B, C for different network sizes; Class D for multicast; Class E for experimental.
- Private vs. Public IPs: Private for internal use; public for internet-facing devices.
- CIDR Notation: Flexible IP allocation and routing notation.
- Subnetting: Divides large networks into smaller subnets for better management, performance, and security.
- Application in Penetration Testing: Crucial for network mapping, host discovery, and assessing network segmentation.
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