NPTEL Ethical Hacking Review

Vocabulary practice flashcards covering core concepts, protocols, attack types, and tools from the NPTEL Ethical Hacking course assignments.

CIA Triad

A foundational information security model consisting of three core principles: Confidentiality, Integrity, and Availability.

Black Box Model

A penetration testing model where the tester has no prior knowledge or information about the target network.

White Box Model

A penetration testing model where the tester possesses complete information regarding the target network.

Gray Box Model

A penetration testing approach that provides the tester with partial information about the target environment.

Packet-Switched Network

A communication network where data is broken into smaller packets and multiple connections share the same physical transmission link without requiring prior circuit setup.

Data Link Layer

The OSI layer responsible for organizing raw bits into frames, implementing MAC addressing, and performing error detection over a physical link.

IP Address

A logical network identifier used to uniquely distinguish a host or network interface to enable packet routing across networks.

Time to Live (TTL)

An IPv4 header field decremented by $1$ at each router hop to discard packets and prevent infinite routing loops when its value reaches $0$.

HLEN

An IP header field that defines the length of the header in multiples of $32$ bits ($4$ bytes).

MAC Address

A physical hardware address situated at the data link layer, consisting of $48$ bits typically represented as $12$ hexadecimal digits.

Don't Fragment (DF) Bit

A flag in the IPv4 header that, when set to $1$, causes a router to drop the packet and issue an ICMP "Fragmentation Needed" message if the packet exceeds the path MTU.

RFC 1918

The standard defining the private IPv4 address allocations: $10.0.0.0/8$, $172.16.0.0/12$, and $192.168.0.0/16$.

UDP Header

An $8$-byte connectionless transport layer header containing four $2$-byte fields: source port, destination port, length, and checksum.

Connectionless Routing

An IP routing approach where each packet is evaluated and routed independently, permitting packets between the same host pair to traverse different paths.

Routing Table H Flag

A flag indicating that a specific routing table entry applies only to an individual host rather than an entire subnet or network.

OSPF Hello Packet

A periodic packet type transmitted between OSPF routers to establish adjacency and confirm that a neighboring router is alive and active.

Border Gateway Protocol (BGP)

An exterior gateway routing protocol designed to exchange routing and reachability information between distinct autonomous systems.

Routing Information Protocol (RIP)

An interior distance-vector routing protocol operating inside an autonomous system that is vulnerable to the count-to-infinity problem.

IPv6 Base Header

A fixed $40$-byte network layer header that contains an $8$-bit Hop Limit field and eliminates intermediate router fragmentation.

Hypervisor

A Virtual Machine Monitor (VMM) enabling the creation, execution, and resource allocation of multiple virtual machines on a single physical host.

Whois Lookup

A query protocol used to obtain domain ownership details, name servers, contact information, and registration expiration dates.

VirtualBox NAT Mode

A default VirtualBox networking profile that assigns guest machines a virtual private IP address, provides internet access, and masks them behind the host.

Nmap -sV

An Nmap scan flag used to interrogate open ports and detect service and version information on a target system.

Nmap -Pn

An Nmap option that skips the host discovery phase entirely, treating all specified IP addresses as active and immediately beginning port scans.

Crunch

A specialized utility designed to generate custom password wordlists based on defined character sets, lengths, and patterns.

Hydra

A parallelized network authentication cracking tool used to perform rapid brute-force and dictionary attacks against network login services.

CAM Table Flooding

An attack that overloads a switch's Content Addressable Memory table with bogus MAC addresses, forcing it into fail-open mode where it broadcasts all frames like a hub.

Masquerade Attack

An attack wherein a malicious actor impersonates an authorized identity to obtain illegitimate access to systems or resources.

Interruption Attack

A classification of security attacks directly targeting availability, such as Denial-of-Service attacks that render services unreachable to legitimate users.

Data Encryption Standard (DES)

A symmetric-key block cipher that operates on $64$-bit plaintext blocks using an effective key length of $56$ bits.

Collision Resistance

A cryptographic hash property making it computationally infeasible to find any two separate inputs that map to the identical output hash digest.

Non-repudiation

A security assurance provided by digital signatures ensuring that a sender cannot deny having authored or dispatched a specific message.

IPSec Transport Mode

An IPSec operation mode that encrypts exclusively the transport layer payload while leaving the original IP packet header untouched.

Steganography

The practice of concealing secret data within an ordinary cover medium such as an image, audio clip, or executable without revealing that information is hidden.

Behavioural Biometrics

Authentication methods derived from dynamic human behavioural patterns, such as keystroke dynamics, gait, and signature dynamics.

Smurf Attack

A distributed DoS attack that broadcasts ICMP Echo requests with a forged victim IP address, triggering all hosts on the subnet to flood the victim with Echo replies.

SYN Flooding

A DoS attack that consumes server resources by sending numerous TCP SYN connection requests without returning the final ACK, leaving ports in a half-open state.

Promiscuous Mode

A network interface card operational mode enabling the device to capture all packet traffic on a network segment, irrespective of the intended destination MAC address.

Slowloris

A Denial-of-Service attack tool that occupies web server capacity by establishing concurrent connections and transmitting partial HTTP requests indefinitely.

ARP Spoofing

A sniffing mechanism that broadcasts false Address Resolution Protocol messages linking an attacker's MAC address with a target host's IP address to intercept traffic.

Side-Channel Attack

A cryptographic attack targeting physical system implementation variables—such as power usage, timing variations, or electromagnetic radiation—rather than algorithmic design.

Physically Unclonable Function (PUF)

A hardware security primitive that generates unique, deterministic responses from device-specific microscopic manufacturing variations.

Hardware Trojan

A deliberate, unauthorized circuit alteration introduced during integrated circuit design or manufacturing that executes malicious payloads when triggered.

Exploit Module

A Metasploit Framework module written specifically to leverage a target software or system flaw to gain unauthorized access.

Meterpreter Hashdump

A Metasploit command executed within Meterpreter to extract stored password hashes from the target operating system's database.

Dirb

A web content scanner that uses dictionary-based wordlists to discover hidden files and directories on a web server.

Error-based SQL Injection

A vulnerability where unvalidated inputs force database errors that are displayed to the user, leaking database structures and schema details.

TCP Connect Scan (-sT)

An Nmap port scanning mechanism that completes the full TCP three-way handshake (SYN, SYN-ACK, ACK) to confirm whether a port is open.