Computer Networks

The IKE (Internet Key Exchange) protocol uses the Diffie-Hellman algorithm to securely exchange keys over an insecure network, allowing peers to calculate a shared secret key.

IKE Phase 1 establishes a secure channel (ISAKMP SA), while IKE Phase 2 uses that secure channel to negotiate the IPsec security associations (SAs) that will protect the actual data traffic.

NAT-Traversal (NAT-T) detection occurs during the initial IKE Phase 1 exchange (specifically in the main or aggressive mode) to determine if there is a NAT device between the peers. If detected, the peers will encapsulate ESP packets in UDP port 4500.

GRE (Generic Routing Encapsulation) is a tunneling protocol that creates a virtual point-to-point link to encapsulate a wide variety of network layer protocols inside virtual point-to-point links. It does not provide encryption by itself, which is why it is often paired with IPsec.

OpenVPN uses the OpenSSL library to provide secure communication, utilizing SSL/TLS protocols for the initial key exchange and authentication between the client and the server.

L2TP (Layer 2 Tunneling Protocol) and OpenVPN are both widely recognized protocols used to create VPN tunnels. PPP is a data link layer protocol, and PCAP is a packet capture format.

VPNs work by encapsulating original data packets (which may contain Ethernet frames) inside new IP packets, allowing them to be transmitted securely over a public network.

Nmap is a popular tool used for port scanning, which is the process of identifying open ports on a network host. It can be used to discover services running on a host, identify potential vulnerabilities, and gather information about the network configuration.

Standard protocols provide a common language and set of rules for communication, data exchange, and system integration, ensuring interoperability and reducing the complexity of integration efforts.

HTTP, FTP, and Web Services are commonly used data access protocols in astroinformatics for retrieving data from remote sources.

Latency, also known as delay, measures the time it takes for a packet to travel from one point to another in a network. It is a critical factor in determining the responsiveness and user experience of network applications.

Packet Delivery Ratio (PDR) is a metric that indicates the proportion of packets that are successfully transmitted from a source to a destination without being lost or corrupted during transmission.

Simple Network Management Protocol (SNMP) is a widely used protocol for monitoring network devices and collecting performance metrics. It allows network administrators to gather information about device status, performance, and configuration, enabling them to identify and resolve network issues.

Jitter is a metric that measures the variation in the delay of packets transmitted over a network. It is caused by fluctuations in network traffic and can impact the quality of real-time applications such as voice and video calls.

Round-Trip Time (RTT) is a metric that measures the time it takes for a packet to travel from a source to a destination and back. It is commonly used to assess network latency and responsiveness.