FIT5037 - Lecture 03: Transport Layer Security & Attacks Flashcards

Question 1

Transport Layer

Accepted Answer

Offers end-to-end communication for application layers, including reliable, in-order data delivery and congestion control.

Question 2

TCP (Transmission Control Protocol)

Accepted Answer

A point-to-point, reliable, full-duplex protocol providing an in-order byte stream connection between one sender and one receiver.

Question 3

MSS (Maximum Segment Size)

Accepted Answer

The largest amount of data, specified in bytes, that a device can handle in a single, unfragmented TCP segment.

Question 4

Port Number

Accepted Answer

A 16-bit field in the TCP header used to identify specific application processes on a host, such as HTTP 80, HTTPS 443, or FTP 21.

Question 5

Sequence Number (TCP)

Accepted Answer

A 32-bit TCP header field specifying the sequence number of the first byte of data in the segment, or the Initial Sequence Number (ISN) if the SYN bit is set.

Question 6

Acknowledgement Number (TCP)

Accepted Answer

A 32-bit TCP header field containing the next sequence number expected by the sender of the segment, valid only when the ACK bit is set.

Question 7

TCP 3-way Handshake

Accepted Answer

The connection establishment process consisting of three steps: Client SYN (seq=x), Server SYN-ACK (seq=y, ACK=x+1), and Client ACK (seq=x+1, ACK=y+1).

Question 8

TCB (Transmission Control Block)

Accepted Answer

A data structure used by a server to store connection-state information (including IPs, ports, and sequence numbers) upon receiving an initial SYN packet.

Question 9

Half-open Connection

Accepted Answer

A connection state where only the client-to-server connection is established and the server-side TCB remains in a dedicated queue waiting for the final ACK.

Question 10

SYN Flooding Attack

Accepted Answer

A Denial of Service (DoS) attack where an attacker continuously sends SYN packets (often using spoofed source IPs) and never sends the final ACK, filling the server's half-open TCB queue and blocking new users.

Question 11

SYN Cookies

Accepted Answer

A countermeasure to SYN flooding where the server doesn't allocate queue space for half-open connections, instead encoding connection details in a keyed hash sent as the server's Initial Sequence Number.

Question 12

TCP Reset Attack

Accepted Answer

An attack where a spoofed TCP packet with the RST flag set is sent to abruptly terminate an active connection, requiring the attacker to spoof IP addresses, ports, and a valid sequence number.

Question 13

TCP Session Hijacking

Accepted Answer

An attack where an adversary injects data into an active TCP connection (potentially triggering a buffer overflow) by spoofing IP addresses, ports, and expected sequence numbers.

Question 14

Transport Layer Security (TLS)

Accepted Answer

A cryptographic protocol situated between the Transport and Application layers that provides confidentiality, integrity, and authentication.

Question 15

TLS Layer Placement

Accepted Answer

Sitting directly between the Application layer and Transport layer, TLS accepts unprotected data from the application, manages encryption, decryption, and integrity checks, and hands protected records to the Transport layer.

Question 16

Confidentiality (TLS)

Accepted Answer

The assurance that only the two authenticated endpoints of the secure channel can view the plaintext contents of the transmitted data.

Question 17

Integrity (TLS)

Accepted Answer

The secure channel's capability to detect any modification, deletion, or insertion of data occurring during transmission.

Question 18

Authentication (TLS)

Accepted Answer

The process of verifying the identity of at least one end of the channel (usually the server) so the other party knows who they are communicating with.

Question 19

TLS Record Protocol

Accepted Answer

The protocol used after connection establishment to transmit data, where application payload is fragmented, optionally compressed, secured with a MAC/padding, encrypted, and prefixed with a TLS header.

Question 20

TLS Record Header

Accepted Answer

A 5-byte header prepended to TLS records consisting of: Content Type (1 byte), TLS Version (2 bytes), and Record Length (2 bytes).

Question 21

TLS Handshake Protocol

Accepted Answer

The protocol used to negotiate cryptographic parameters, authenticate endpoints (using certificates), and establish shared session keys before any application data is sent.

Question 22

TLS Handshake Step 1: Client Hello

Accepted Answer

The initial message sent by the client containing supported cipher suites, TLS version, and a client-generated random number.

Question 23

TLS Handshake Step 2: Server Hello

Accepted Answer

The server's response selecting the highest mutually supported TLS version, a cipher suite, and providing a server-generated random number.

Question 24

TLS Client Key Exchange

Accepted Answer

A handshake message where the client sends key material (such as a pre-master secret encrypted with the server's public key or Diffie-Hellman parameters) to establish a master secret.

Question 25

Change Cipher Spec Protocol

Accepted Answer

A signal during the TLS handshake notifying the receiving party that all subsequent records will be encrypted using the newly negotiated keys and parameters.

FIT5037 - Lecture 03: Transport Layer Security & Attacks

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