📄 ️ ARP
ARP (Address Resolution Protocol) is a fundamental protocol used in the Internet Protocol (IP) suite for finding the media access control (MAC) address corresponding to a given Internet Protocol (IP) address. Its primary purposes include:
📄️ AS
An Autonomous System, commonly abbreviated as AS, is a collection of IP routing prefixes under the control of one or more network operators that presents a common, clearly defined routing policy to the internet. Essentially, an AS is a group of IP networks operated by one or more network operators that have a single and clearly defined external routing policy.
📄️ AST
An Abstract Syntax Tree, commonly abbreviated as AST, is a tree representation of the abstract syntactic structure of source code written in a programming language. Each node of the tree denotes a construct occurring in the source code.
📄️ BGP
BGP (Border Gateway Protocol) is a crucial protocol used for routing data across the internet. It's classified as a Path Vector protocol, and it's unique in its role and functionality in global internet routing.
📄️ CDP
The Cisco Discovery Protocol (CDP) is a proprietary data link layer protocol developed by Cisco Systems. It's used to share information about other directly connected Cisco equipment, such as routers, switches, and bridges.
📄️ Cisco Port Abbreviations
Cisco using the following abbreviations for common port speeds:
📄️ Dig
dig (Domain Information Groper) is a command-line tool used for querying DNS (Domain Name System) servers. It's a powerful utility for network administrators and is commonly used for troubleshooting DNS problems, but it's also useful for understanding DNS workings more generally.
📄️ dot1q
IEEE 802.1Q is an important networking standard, often referred to simply as "dot1q". It defines a technique for tagging Ethernet frames with VLAN (Virtual Local Area Network) information, enabling more flexible network segmentation, management, and enhanced security.
📄️ EIGRP
Enhanced Interior Gateway Routing Protocol (EIGRP) is an advanced distance-vector routing protocol that is used in computer networks to automate routing decisions and configuration. Developed by Cisco, EIGRP is designed to offer superior internal routing capabilities within autonomous systems.
📄️ HSRP
HSRP (Hot Standby Router Protocol) is a Cisco proprietary redundancy protocol designed to allow for transparent failover of a first-hop IPv4 router. HSRP ensures that traffic continues to flow even if the currently active router fails, by automatically redirecting traffic to a standby router. It is widely used in local area network (LAN) environments to ensure high availability and reliability of network connections.
📄️ HTTP Status Codes
Common Codes
📄️ IEEE
The Institute of Electrical and Electronics Engineers (IEEE) is an international organization composed of professionals in electrical engineering, electronics, computer science, and related fields. It is known for its development of standards, particularly in the area of telecommunications, computer networking, and other technical areas of information technology.
📄️ IPerf
IPerf is a network testing tool that can create TCP and UDP data streams and measure the throughput of a network that is carrying them. It's an open-source tool and can run on various platforms including Windows, Linux, and Unix. IPerf has two components: a server and a client.
📄️ iptables
iptables is a user-space utility program that allows a system administrator to configure the IP packet filter rules provided by the Linux kernel firewall, implemented as different Netfilter modules. The filters are organized into different tables, which contain a series of rules that dictate how to handle network traffic.
📄️ LACP
LACP (Link Aggregation Control Protocol) is a protocol defined by IEEE standard 802.3ad (now part of IEEE 802.1AX). LACP allows multiple physical network links (Ethernet cables, for instance) to be bundled together to form a single logical link. This process is known as link aggregation or port channeling.
📄️ LLDP
The Link Layer Discovery Protocol (LLDP) is an open standard network protocol used for discovering information about neighboring devices on a local area network. Unlike Cisco's proprietary Cisco Discovery Protocol (CDP), LLDP is vendor-neutral and widely supported across different network device manufacturers. Here's a detailed explanation of its features, functionality, and typical use cases:
📄️ LLMNR
Link-Local Multicast Name Resolution (LLMNR) is a protocol defined by RFC 4795 that allows hosts on the same local network to perform name resolution for other hosts when DNS (Domain Name System) is not available. LLMNR is used in IPv4 and IPv6 networks and operates similarly to NetBIOS Name Service (NBNS) but with a few enhancements for handling name resolution in local link networks.
📄️ Loopback Interface
A loopback interface is a virtual network interface implemented in software. It's a special, non-physical interface typically found in computer networking systems. In IP networking, the loopback interface is commonly assigned the address range of 128.0.0.1 to 127.255.255.255 in IPv4, or ::1 in IPv6.
📄️ MPLS
Multiprotocol Label Switching (MPLS) is a data-carrying technique for high-performance telecommunications networks. It directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table.
📄️ mtr
mtr (My Traceroute) combines the functionality of the traceroute and ping programs in a single network diagnostic tool. It provides a continuously updated display of the route packets take to a specified network destination and the response times of these hops.
📄️ NAT & PAT
Network Address Translation (NAT)
📄️ Netstat
netstat (network statistics) is a versatile command-line tool that is invaluable for network administrators and engineers. It provides information about network connections, routing tables, interface statistics, masquerade connections, and multicast memberships.
📄️ Nmap
Nmap (Network Mapper) is a powerful and versatile tool used for network discovery and security auditing. It's primarily used for:
📄️ OSPF
Open Shortest Path First (OSPF) is a robust, scalable link-state routing protocol used in IP networks. It's classified as an Interior Gateway Protocol (IGP), used for routing within an Autonomous System (AS).
📄️ RIP
RIP (Routing Information Protocol) is one of the oldest distance-vector routing protocols used in network routing. Primarily used in smaller, less complex networks, RIP is known for its simplicity and ease of configuration.
📄️ Rsync
rsync is a highly versatile file synchronization and file transfer utility. It's widely used for efficiently transferring and synchronizing files across computer systems, utilizing various network protocols. The key advantage of rsync is its ability to transfer only the changes made to files, optimizing bandwidth usage and reducing transfer times.
📄️ SD-WAN
SD-WAN, or Software-Defined Wide Area Network, is an advanced approach to network connectivity that seeks to simplify the management and operation of a WAN by decoupling the networking hardware from its control mechanism. This is achieved using software-defined networking (SDN) concepts.
📄️ sed
sed, short for "stream editor", is a powerful and versatile text processing tool available on Unix, Linux, and similar operating systems. It's primarily used for parsing and transforming text in a stream (i.e., a file or input from a pipeline).
📄️ SNAT
Source Network Address Translation (SNAT) is a subtype of Network Address Translation (NAT) that modifies the source address of IP packets as they pass through a router or firewall. SNAT is specifically used to change the private IP addresses of source devices in a local network to a public IP address or addresses for outgoing traffic to the internet or another external network.
📄️ ss
The ss (socket statistics) command is a utility for investigating sockets in Linux and Unix systems. It's a modern replacement for the older netstat command, offering more information and faster execution. ss is used to display various network statistics and is a powerful tool for diagnosing issues and monitoring network performance.
📄️ STP
Spanning Tree Protocol (STP) is a fundamental network protocol that is essential for the operation of Ethernet networks. It plays a crucial role in maintaining a loop-free network topology.
📄️ Subnet
Example Subnet 10.1.1.0/24
📄️ Tcpdump
tcpdump is a powerful command-line packet analyzer tool, widely used in the field of network administration and security. It allows users to capture and analyze network traffic passing through a system. Here's a detailed overview of tcpdump, including its functionalities and common commands and options.
📄️ Telnet
Telnet is one of the oldest network protocols that is used for interacting with remote computers over a network. It provides a bidirectional interactive text-based communication facility using a virtual terminal connection. However, it's important to note that telnet does not encrypt any data, including login credentials, making it insecure for most modern uses.
📄️ tmux
tmux is a terminal multiplexer, a command-line tool used to manage multiple terminal sessions within a single window. It's popular in Unix-like operating systems, such as Linux and macOS.
📄️ Traceroute
Traceroute is a network diagnostic tool used for tracking the pathway taken by a packet across an IP network from source to destination. It helps in identifying the route and measuring transit delays of packets across an Internet Protocol (IP) network.
📄️ VDOM
A Virtual Domain (VDOM) is a technology used in network devices, such as firewalls and routers, to partition a single physical device into multiple independent virtual devices. Each VDOM can have its own set of rules, policies, and configurations, functioning as if it were a separate physical device. This concept is particularly prevalent in firewalls, where it enhances security, management, and multi-tenancy capabilities.
📄️ VRF
Definition
📄️ VXLAN
VXLAN (Virtual Extensible LAN) is a network virtualization technology that addresses the scalability problems associated with large cloud computing deployments. It's an overlay technology, meaning it allows you to create a logical network for your virtual machines across different networks.