Security ( Filtering, DOS, Firewalls)

DOS stands for Denial of Service when it comes to firewalling. Denial of Service refers to a type of cyber attack where the attacker overwhelms a network or system with excessive traffic or requests, causing it to become unavailable to legitimate users. Firewalls are security measures that protect networks by monitoring and controlling incoming and outgoing network traffic. In this context, DOS refers to the ability of a firewall to detect and prevent denial of service attacks, ensuring the availability and integrity of the network.

SYN flood is a type of denial-of-service attack where an attacker floods a target's system with a series of SYN requests. The attacker sends a large number of SYN packets to the target server, but does not complete the handshake process by sending the final ACK packet. This causes the target system to allocate resources and keep waiting for the final ACK, eventually exhausting its resources and making it unable to respond to legitimate requests.

ESP (Encapsulating Security Payload) is a protocol used in IPSec (Internet Protocol Security) to provide confidentiality, integrity, and authentication for data packets. It is not the only type of IPSec header, but it is an important component. ESP encapsulates the original IP packet and adds a new ESP header, which includes encryption and authentication information. It ensures that the data is protected from unauthorized access, maintains its integrity during transmission, and verifies the authenticity of the sender. ESP operates at the network layer and sits behind the UDP header, providing end-to-end security for IP traffic.

If traffic doesn't match a rule on the firewall, the default action is to deny the traffic. This means that the firewall will block or reject the traffic and not allow it to pass through.

Protocol anomalies refer to traffic that deviates from the normal behavior of a protocol and could potentially be interpreted as a new network attack. These anomalies can include unusual packet structures, unexpected sequencing or timing, or any other behavior that does not conform to the standard protocol specifications. Detecting and analyzing protocol anomalies is important for identifying and mitigating potential network attacks, as they may indicate the presence of malicious activity or attempts to exploit vulnerabilities in the network.

IPSec is a protocol suite used for securing IPv4 traffic. It provides authentication, confidentiality, and integrity for data transmitted over IP networks. It is also commonly referred to as IP Security. IPSec can be used for both site-to-site and remote client VPN access, making it a versatile solution for securing network communications. Therefore, the correct answer is "all of the above."

IDS/IDP devices operate at layers 3-7 in the OSI model. This means that they can analyze network traffic and detect intrusions or malicious activity at various levels, including the network layer (layer 3), transport layer (layer 4), session layer (layer 5), and application layer (layer 7). By operating at these layers, IDS/IDP devices can provide a more comprehensive and detailed analysis of network traffic, allowing for better detection and prevention of security threats.

Destination NAT typically occurs for access to internal devices on a network that sit behind a router/firewall. This means that when external devices or users want to access a specific internal device, the destination NAT translates the destination IP address of the incoming packets to the internal IP address of the device. This allows external access to internal resources without exposing the internal IP addresses to the outside world.

IDP devices typically operate in transparent mode. In this mode, the devices are placed between the network segments and act as a bridge, allowing the traffic to pass through without any disruption. The devices monitor the network traffic for any suspicious or malicious activity and can take preventive actions to block or mitigate the threats. Transparent mode is preferred as it does not require any changes to the existing network infrastructure and does not introduce any additional latency or points of failure.

Source NAT typically occurs for traffic passing out to the internet where not enough IP addresses are available. This is because Source NAT allows multiple devices within a private network to share a single public IP address when communicating with the internet. By translating the source IP addresses of the outgoing traffic, Source NAT enables the private network to connect to the internet using a limited number of available public IP addresses.