Networking Fundamentals_this is a test
Essential networking concepts every security professional should know.
NetworkingFundamentalsReference
Networking Fundamentals
Core networking knowledge for cybersecurity professionals.
OSI Model
- Physical: Cables, hubs
- Data Link: Switches, MAC addresses
- Network: Routers, IP addresses
- Transport: TCP, UDP
- Session: Session management
- Presentation: Encryption, compression
- Application: HTTP, DNS, FTP
TCP/IP Model
- Network Access: Physical + Data Link
- Internet: IP, ICMP, ARP
- Transport: TCP, UDP
- Application: HTTP, DNS, etc.
Common Ports
| Port | Protocol | Service |
|---|---|---|
| 21 | TCP | FTP |
| 22 | TCP | SSH |
| 23 | TCP | Telnet |
| 25 | TCP | SMTP |
| 53 | UDP/TCP | DNS |
| 80 | TCP | HTTP |
| 443 | TCP | HTTPS |
| 445 | TCP | SMB |
| 3389 | TCP | RDP |
Subnetting Cheat Sheet
| CIDR | Subnet Mask | Hosts |
|---|---|---|
| /24 | 255.255.255.0 | 254 |
| /25 | 255.255.255.128 | 126 |
| /26 | 255.255.255.192 | 62 |
| /27 | 255.255.255.224 | 30 |
| /28 | 255.255.255.240 | 14 |
Three-Way Handshake
- Client → Server: SYN
- Server → Client: SYN-ACK
- Client → Server: ACK
Connection established!
DAAS