Network Fundamentals
This device connects different networks and operates at Layer 3 using IP addresses.
What is a router?
An attacker secretly positions themselves between two parties and relays their traffic.
What is a Man-in-the-Middle (MITM) attack?
Switches operate at this OSI layer, forwarding frames based on MAC addresses.
What is Layer 2 (the Data Link layer)?
This command-line tool is the go-to for scanning a network to discover live hosts and open ports.
What is nmap?
NAC
What is Network Access Control?
This protocol maps IP addresses to MAC addresses on a local network and has no authentication.
What is ARP (Address Resolution Protocol)?
Sending forged ARP replies to poison the caches of a victim and the gateway.
What is ARP spoofing?
ARP is famously awkward to place because it bridges these two adjacent OSI layers.
What are Layer 2 and Layer 3 (Data Link and Network)?
Daily Double: What Branch of the Military is Robert in, and what does he do?
Air Force, Cybersecurity
DNSSEC
What are Domain Name System Security Extensions?
Dividing a network into smaller isolated zones to limit an attacker's movement.
What is segmentation?
Silently downgrading a victim's HTTPS connection to plain HTTP so it can be read.
What is SSL stripping?
This connectionless Layer 4 protocol has no handshake and is the usual transport for DNS queries and video streaming.
What is UDP?
The "three-way handshake" of SYN, SYN-ACK, ACK establishes a connection using this Layer 4 protocol.
What is TCP?
802.1X
What is Port-Based Network Access Control? (accept "IEEE port-based NAC")
The security model that trusts no user or device by default — even inside the network.
What is Zero Trust?
The post-login credential an attacker can steal to impersonate you — no password or MFA needed.
What is a session token (cookie)?
SSL stripping and HSTS both operate around this protocol that encrypts traffic at the session/presentation boundary.
What is TLS (Transport Layer Security)?
In this DNS-based data-exfiltration technique, stolen data is smuggled out encoded inside DNS query names to an attacker-controlled domain.
What is DNS tunneling?
EAP-TLS
Extensible Authentication Protocol – Transport Layer Security?
The port-based network access control standard that authenticates a device or user before the switch port opens.
What is 802.1X?
This NAC fallback for printers and IoT relies only on a MAC address — making it trivially spoofable and a favorite attacker bypass.
What is MAC Authentication Bypass (MAB)?
This Layer 3 protocol carries the error and diagnostic messages behind tools like ping and traceroute — and is often abused for network reconnaissance.
What is ICMP?
This Layer 2 attack lets a device hop onto a VLAN it shouldn't reach by abusing a switch's automatic trunk negotiation (DTP).
What is VLAN hopping (switch spoofing)?
HSTS
What is HTTP Strict Transport Security?