This guide walks through enabling the firewall, opening specific ports, and reloading rules on CentOS 7 using firewalld and on CentOS 6 using iptables, providing exact commands, optional parameters, and troubleshooting tips for successful network configuration.
This article demystifies the true reasons behind Redis's speed by exploring low‑level I/O mechanisms—from basic BIO to NIO and the Reactor model—explaining socket creation, connection handling, blocking behavior, and how Java’s non‑blocking APIs and system calls work together to achieve high‑throughput networking.
This article explores the design motivations behind HTTP, tracing its evolution from the early TCP‑based request‑response model through HTTP/0.9, 1.0, 1.1, to modern HTTP/2 and HTTP/3, highlighting key features like headers, caching, connection reuse, and protocol optimizations.
This article details the design, bandwidth optimization, and reliability strategies of a custom bullet‑chat system for Southeast Asian live streaming, covering background challenges, problem analysis, compression, request throttling, long‑polling versus WebSocket trade‑offs, and a short‑polling solution that successfully supported 700 k concurrent users.
This article compiles common Docker interview questions and provides detailed explanations, covering Docker fundamentals, use cases, advantages, differences from virtual machines, core components, installation steps, storage configuration, image management, container creation, networking modes, data volumes, private registry setup, backup procedures, and MySQL deployment, all illustrated with practical command examples.
The article details Bilibili’s internal DNS service evolution—from an initial BIND9 master‑slave setup to a multi‑level caching architecture that boosts QPS to over 1.5 million—while describing comprehensive host, business, and client monitoring, key configuration pitfalls, and best‑practice recommendations for a low‑latency, reliable intranet DNS.
This guide explains key Linux networking commands—including ip, ifconfig, netstat, ping, traceroute, DNS utilities, and DHCP tools—showing how to view interfaces, check connectivity, trace routes, query DNS records, and manage DHCP leases for effective network troubleshooting.
This guide explains how to use Linux's TC tool to shape traffic by creating qdisc, class, and filter rules, allowing you to limit outbound and inbound bandwidth for specific IP addresses or ports, with step‑by‑step commands and practical examples.
This guide explains the benefits of caching, defines key DNS concepts, and provides language‑specific investigations and code samples to help developers implement client‑side DNS caching, reduce lookup latency, and improve overall network performance.
This article explains Calico's IPIP networking mode in Kubernetes, covering its architecture, core components, routing behavior, command‑line examples, and packet‑capture analysis to illustrate how pods communicate across nodes.
This article details the architectural decisions, network protocol choices, message framing strategies, and server‑level optimizations—including Netty adoption, TCP handling, token management, load balancing, NIC queue configuration, and CPU affinity—that enable a scalable, low‑latency instant messaging service supporting millions of concurrent connections.
This article examines the RoCE protocol, its evolution and variants, lossless networking and congestion‑control mechanisms, practical performance measurements on HPC clusters, and the advantages and limitations of deploying RoCE in high‑performance computing environments.
This article provides a detailed tutorial on the curl command-line tool, covering its purpose, common options such as -A, -H, -b, -c, -d, -F, -L, -k, and advanced usage like file uploads, proxy settings, and response testing, with practical code examples for each.
This article introduces the concept of innovation networks, outlines the four key roles—Inventor, Transformer, Financier, and Broker—explains how they fit within a broader innovation ecosystem, and provides guidance on aligning values, assessing organizational capabilities, and mapping metrics to improve network delivery.
This guide explains how to monitor Linux system performance by using core commands such as top, vmstat, iostat, and sar to evaluate CPU usage, memory allocation, I/O activity, and network traffic, while also covering load interpretation, cache behavior, huge pages, zero‑copy techniques, and practical command examples.
This article details the step‑by‑step evolution of a multi‑cloud network at Zuoyebang, covering three construction phases, quality‑improvement measures such as fault prevention and rapid recovery, and ongoing operational governance that together deliver a flexible, high‑availability cloud infrastructure.
This article provides a detailed overview of Docker, covering its definition, core components, advantages over virtual machines, common use cases, installation steps, storage configuration, image management commands, network modes, data volumes, private registry setup, backup procedures, and MySQL deployment, all illustrated with practical command examples.
The article explains how a senior architect leverages SSH reverse tunneling and remote port forwarding to enable a headquarters server to reach a branch office's internal web server despite restrictive network policies, detailing the commands, verification steps, and packet flow involved.
This article walks through installing BIND, configuring the named.conf file, creating forward and reverse zone files, setting up a master DNS server and a slave server, starting the services, and verifying the setup with nslookup, including a fail‑over test.
This guide explains how Linux uses packet queuing for traffic shaping, walks through creating qdisc, class, and filter structures with tc, and shows step‑by‑step commands to limit bandwidth for specific IPs, ports, and inbound traffic using ifb devices.
The 2022 ODCC summit in Beijing showcased 55 innovative achievements across servers, networks, data‑center facilities, edge computing and intelligent monitoring, unveiling whitepapers, industry standards, OSSP specifications, liquid‑cooling guidelines, green data‑center practices, high‑performance networking and AI‑driven operations to promote low‑carbon, high‑efficiency computing infrastructure.
This article explains the definition of cloud native, its industry impact, technical characteristics, architectural design principles, and the essential technologies—including containers, serverless containers, bare‑metal containers, microservices, serverless computing, specialized chips, networking, and databases—that together enable elastic, resilient, and observable cloud‑first applications.
This article explains how TCP connections behave when any of the three-way handshake or four-way termination packets are lost, detailing the kernel‑controlled retransmission mechanisms, timeout intervals, relevant sysctl parameters, and the exact sequence of events for each loss scenario.
This article explains how hardware architecture, Linux OS version, kernel configuration, OVS integration, memory management, NUMA awareness, and CPU micro‑architecture affect DPDK application performance and provides concrete tuning steps such as CPU isolation, service disabling, huge‑page setup, and optimized memory allocation.
This article explains the fundamentals of TCP/UDP and HTTP, details OkHttp's interceptor chain and caching mechanisms, and demonstrates a generic offline‑upload solution using Kotlin reflection to persist and replay network calls when connectivity is restored.
The whitepaper introduces a comprehensive DPU performance benchmark methodology, detailing evaluation criteria across network, storage, compute, and security dimensions, and provides guidance on building test systems, selecting workloads, and designing metrics to enable fair, open, and objective assessment of diverse DPU products.
This article provides an in‑depth technical overview of Wi‑Fi, covering its terminology, frequency bands, 802.11 standards evolution, channel planning, antenna gain, power calculations, MIMO, mesh networking, AC + AP architectures, and practical deployment considerations for optimal wireless performance.
This guide introduces tmux, the powerful terminal multiplexer for Linux, covering core session, window, and pane commands along with handy keyboard shortcuts, and also explains how to identify physical network interfaces using ethtool, providing practical examples for everyday system administration.
This article explains how to obtain a user's IP address from an HttpServletRequest in Java, convert it to geographic location using the ip2region library, and provides detailed code examples, Maven setup, caching strategies, and performance testing procedures for backend developers.
This article uses a restaurant analogy to demystify Keepalived’s routing mechanisms, detailing the three routing modes—NAT, TUN, and Direct Routing (DR)—their configurations, underlying principles, advantages, limitations, and practical deployment considerations within load‑balancing environments.
The article analyzes how the shift of data centers toward compute-centric architectures drives the need for high‑performance networking, explains the shortcomings of TCP/IP, compares InfiniBand, iWarp and RoCE protocols, and shows why loss‑less Ethernet with RDMA is critical for modern HPC workloads.
Rocky Linux 9 builds on RHEL 9 with the open‑source Peridot build system and introduces major security upgrades, modern networking tools, GNOME 40 desktop improvements, and filesystem enhancements like XFS DAX support, positioning it as a compelling RHEL‑compatible enterprise OS.
This article demonstrates how to install the psutil Python library and use it to gather detailed CPU, memory, disk, network, and process information on a system, providing code examples and explanations for each type of metric.
This article explains how to obtain a user's IP address in Java, map it to its geographic location using the ip2region library, and integrate the solution into a backend project with Maven, complete code examples, and details on the library's three query algorithms.
This tutorial explains how to set up software load balancing using HAProxy and achieve high availability with Keepalived, covering architecture, installation, configuration files, VRRP failover, load‑balancing algorithms, session persistence, SSL offloading, and traffic routing.
This article explains how the Kube-OVN controller watches pod events, queues them, and uses functions like handleAddPod, getPodKubeovnNets, and getPodAttachmentNet to allocate and release pod IP/MAC addresses while creating OVN ports and routes, enhancing Kubernetes networking security and operability.
This article explains the evolution of HTTP, the release of the HTTP/3 RFC, how QUIC leverages UDP to provide faster, secure connections with 0‑RTT handshakes, solves head‑of‑line blocking, improves congestion and flow control, and details its core mechanisms such as connection migration and ACK handling.
This guide explains how to use key Windows command‑line tools such as ipconfig, msg, net user, net share, nslookup, netsh, telnet, and command chaining operators to query IP information, manage accounts, view shares, troubleshoot DNS, retrieve Wi‑Fi passwords, and automate tasks.
This guide explains how to use the Linux ss command to view socket information, covering basic usage, options for filtering TCP/UDP/UNIX sockets, suppressing headers, showing listening sockets, summarizing statistics, and preventing DNS resolution, with concrete command examples and output screenshots.
This article provides a detailed overview of large‑scale RDMA technology, covering basic concepts, major protocols, network‑level techniques such as congestion control, lossless‑to‑lossy evolution and multipath, virtualization, communication libraries for AI training and storage, performance tuning, monitoring, and real‑world deployment experiences.
This article explains the kube-ovn-cni component of the Kube-OVN project, detailing the CNI workflow, the cmdAdd interface, daemon handling, and the configureNic function that together create and configure pod network interfaces within a Kubernetes cluster.
This step‑by‑step guide explains how to enable IIS on Windows 7, configure an FTP site, set authentication, permissions, virtual directories, ports, and launch the server so you can upload and download files over a LAN.
The Kube-OVN v1.10.0 release introduces Windows node support, user‑defined subnet ACLs, enhanced Kubevirt networking, Submariner multi‑cluster integration, and a series of control‑plane performance optimizations that together improve scalability, flexibility, and stability for cloud‑native Kubernetes deployments.
The article explains how high‑performance computing (HPC) networks overcome TCP/IP limitations by using RDMA‑based technologies such as RoCE v1/v2 and InfiniBand, detailing their architectures, advantages, vendor implementations, and cost‑effective migration to Ethernet‑based solutions for GPU‑driven workloads.
The XQUIC project, Alibaba’s high‑performance open‑source QUIC transport library that powers mobile Taobao and large‑scale gateway services with up to 20 % latency reduction, offers a standards‑compliant stack (QUIC‑Transport, QUIC‑TLS, HTTP/3, qlog) and multi‑path XLINK, and invites students in the Open Source Summer program to extend the code, improve diagnostics, and earn mentorship and rewards.
This article explains the OSI seven‑layer model, the differences between TCP and UDP, the mechanics of TCP three‑way handshake and four‑step termination, how sockets work in Node.js, and how to implement custom protocols and a socket connection pool for high‑concurrency applications.
This article explores the maturation of cloud computing, explains why cloud‑native has become the driving engine for modern workloads, and provides a detailed overview of Kubernetes architecture, its extensibility, and the fragmentation challenges across runtimes, networking, storage, and application management.
This article explains the purpose of network layering, the role of the MAC layer, DHCP and TCP mechanisms, and provides a systematic analysis approach for common Android Wi‑Fi problems such as connection failures, DHCP issues, authentication errors, disconnections, RSSI weakness, beacon time‑outs, ARP/DNS failures, data stalls, TX/RX anomalies, AP‑side events and roaming triggers.
This article explains how Kube-OVN extends KubeVirt networking by providing fixed and stable VM IP addresses, multi‑tenant VPC/Subnet isolation, live‑migration IP preservation, and high‑performance SR‑IOV/OVS‑DPDK acceleration, along with practical configuration examples and reference links.
Learn how to diagnose the “Address already in use” error by listing listening ports on Linux and macOS using netstat, ss, and lsof, understand port concepts, interpret command output, filter results, and find which processes occupy specific ports.
The article dissects netpoll, a Go‑based high‑performance network framework that uses a Multi‑Reactor model with a main and sub‑reactors, detailing its server EventLoop, poll manager load‑balancing across epoll/kqueue, connection buffering and request handling, and the client’s non‑blocking dialing process.
This article details the background, design rationale, network topology changes, and step‑by‑step procedures—including VPC configuration, BGP setup, and port‑channel adjustments—used to upgrade Qunar's data‑center network for Kubernetes deployments, with practical code examples and operational tips.
This article provides a comprehensive guide to Linux Virtual Server (LVS), covering its history, four operating modes, scheduling algorithms, installation steps, MySQL load‑balancing configuration, ARP suppression techniques, and high‑availability setup using keepalived, all illustrated with diagrams and code snippets.
This guide explains why databases like TiDB have specific hardware requirements and provides detailed recommendations for CPU selection, memory tuning, storage choices, and network configuration to achieve optimal performance and cost efficiency.
This article demonstrates how to create a basic FTP‑like file transfer application in C using Windows Winsock, covering both server and client implementations, handling file size negotiation, data transmission loops, and compilation steps, with complete source code examples.
Unplugging a network cable does not immediately terminate a TCP connection; the kernel’s socket state remains ESTABLISHED, and the connection’s fate depends on data transmission, retransmission limits, TCP keepalive settings, and whether either side detects a failure.
The article explains the concepts of forward and reverse proxies, compares their functions and deployment scenarios, and then introduces load balancing principles, layer classifications, and common software such as DNS‑based, reverse‑proxy, NAT, and application‑layer solutions, highlighting their use in backend architectures.
This article explains Redis's high‑performance RESP protocol, its simple design principles, how commands are serialized over TCP, and demonstrates Java examples for both a mock server and client, while detailing the various response types defined by the protocol.
This article compiles a comprehensive set of Linux command‑line shortcuts covering system shutdown, hardware inspection, user management, networking, file handling, compression, performance monitoring, and many other routine administration tasks, providing a handy reference for developers and sysadmins alike.
This article details ByteDance's technical evaluation and implementation of Kube-OVN as a CNI solution for hybrid virtual‑machine and container workloads, covering selection criteria, the initial network design, identified issues, subsequent optimizations, and future roadmap considerations within a cloud‑native Kubernetes environment.
This guide explains how to diagnose the “Address already in use” error by listing listening ports with netstat, ss, and lsof, interpreting their output, filtering results, and locating the offending process on Linux and macOS systems.
This article explores Kafka’s performance architecture, covering network and disk bottlenecks, sequential writes, zero‑copy techniques, page cache usage, Reactor‑based networking, batch processing, compression, partition concurrency, and file structures, providing practical optimization methods for high‑throughput streaming applications.
A detailed post examines why the Xi’an health‑code service collapsed, showing that the lack of CDN for static assets and the resulting 125 Gbps bandwidth demand at 33 k QPS overwhelmed a single data‑center link, rather than any server‑side QR‑code generation issue.
This guide explains how to use essential Linux networking utilities—including ifconfig, ping, traceroute, netstat, dig, nslookup, route, host, arp, ethtool, iwconfig, and hostname—covering their purpose, common options, and practical command‑line examples for system administration tasks.
The article analyses the metaverse as a network-driven evolution, explaining its definition, classifying terminal types, and detailing the new security, ultra‑low‑latency, and deterministic quality‑of‑service requirements that challenge existing internet architecture and design principles.
The article examines the concept of the Metaverse as an evolution of internet access terminals, analyzes how VR/AR headsets reshape communication‑type devices, and discusses the resulting new security, ultra‑low‑latency, and deterministic quality‑of‑service challenges for network infrastructure.
This article traces the evolution of HTTP from its earliest version through HTTP/2, explains the limitations of each iteration, and demonstrates how QUIC's UDP‑based design, 0‑RTT connections, connection migration, and flexible congestion control overcome those issues to become the next‑generation web transport protocol.
This article explains the concept of Quality of Service (QoS) in IP networks, covering its importance, key metrics such as bandwidth, latency, jitter and packet loss, various service models like Best‑Effort, IntServ and DiffServ, and typical application scenarios and deployment considerations.
This article provides a comprehensive collection of public DNS server IP addresses, including nationwide providers and province‑specific Telecom, Unicom, and Mobile DNS entries across China, helping users optimize network resolution and connectivity.
This article details the redesign of Snowball's Android network framework using OkHttp and Retrofit, covering motivations, architectural layers, solutions for domain switching, custom annotations, data validation, migration strategy, and the resulting performance and maintainability improvements.
This article explains how to combine Retrofit with Kotlin coroutines on Android, compares the traditional RxJava method with coroutine-based implementations, and presents two encapsulation techniques—using a DSL and leveraging CoroutineExceptionHandler—to simplify asynchronous network calls and centralize error handling.
This guide explains eight practical wget commands, covering basic file downloads, output redirection, renaming, resume support, batch fetching, site mirroring, custom HTTP headers, response inspection, redirect handling, and expanding short URLs, with clear examples for each scenario.
This article explains two Kotlin‑based network request wrappers for Android that reduce boilerplate by using LiveData, Retrofit, OkHttp and coroutines, compares their design trade‑offs, provides complete Activity, ViewModel, Repository and BaseRepository code samples, and shows how to handle loading, success, error and multiple data sources in a clean MVVM architecture.
The article explains why massive TIME_WAIT TCP connections appear during high‑concurrency scenarios, their impact on server ports and new connections, and provides practical analysis and solutions such as keep‑alive headers, socket reuse, and reducing the TIME_WAIT duration.
This tutorial walks through creating and configuring a Linux bridge, connecting it to veth pairs and a physical NIC, assigning IPs, troubleshooting ARP issues, and demonstrates common use cases for virtual machines and Docker containers.
This guide explains how to use the mii-tool command on Linux to view, configure, and troubleshoot network interface negotiation settings, covering syntax, option meanings, and practical examples for setting duplex modes and restoring auto‑negotiation.
ethtool is a Linux command-line utility for querying and modifying network interface parameters, offering options to view driver info, adjust speed, duplex, offload settings, and perform self-tests, with practical examples demonstrating how to inspect and configure interfaces such as ens33.
This tutorial walks you through creating four VirtualBox Linux VMs, configuring networking, disabling firewalls, installing Java and Perl, setting up password‑less SSH, and preparing a reusable cluster environment that can later host Redis, Kafka, or Storm clusters.
This article presents a comprehensive overview of the open‑source Workflow framework by Sogou, highlighting its high‑performance asynchronous architecture, rich feature set, practical C++ code examples for building servers and clients, and detailed explanations of its task‑flow and timer implementations for backend developers.
This tutorial explains how to use the ipvsadm command to create and manage LVS/NAT and LVS/DR load‑balancing clusters on Linux, covering command syntax, environment setup for director and real servers, ARP tuning, rule persistence, and extended exercises for HTTP, HTTPS, and MySQL traffic.
This guide walks you through systematic troubleshooting of Java production issues—covering CPU, memory, disk, GC, and network problems—by using tools like jstack, jmap, top, iostat, vmstat, and netstat to pinpoint root causes and apply targeted fixes.
This guide walks through practical troubleshooting steps for typical production incidents—including disk exhaustion, high CPU, Java OOM, MySQL deadlocks and slow queries, Redis memory alerts, network TCP issues, and business‑log analysis—providing concrete commands, diagrams and mitigation strategies for each layer.
This article explains the inner workings of the Linux netstat command, walks through reading /proc/net/tcp and related files, demonstrates how to map sockets to processes, and provides a complete Go implementation of a lightweight netstat utility with code examples and detailed parsing logic.
This article explains how to use Python to perform bulk ping tests across large numbers of devices, detailing a custom Pinger class, checksum calculation, packet handling, and a script that iterates through IP ranges to identify reachable hosts efficiently.
This article explains the fundamentals and query process of the Domain Name System (DNS), then details Qunar's evolving DNS architecture—including the initial system, DNSDB management, DNS view, EDNS, HTTPDNS, and intelligent traffic switching—highlighting operational automation and security enhancements.
This article demonstrates how to use a Python script to perform batch ICMP ping tests across dozens or hundreds of network devices, providing a reusable Pinger class, detailed code, and usage examples for efficient network health monitoring.
This tutorial walks through building a three‑node UCloud lab, installing ipvsadm, configuring NAT and TUNNEL load‑balancing modes with LVS, adjusting routing and ARP settings, and verifying the setup using ipvsadm commands and curl requests.
This guide shows how to use shell commands and simple Bash scripts on CentOS 7 to list active network interfaces, extract their IPv4/IPv6 addresses, display MAC addresses, and check link speed using ip, awk, ethtool, and other standard utilities.
This article walks through a detailed investigation of a slow‑response issue in a Kubernetes‑deployed application, covering network topology, full‑link latency statistics, packet captures, kernel‑level bottlenecks, and the final remediation steps to restore performance.
The article introduces load balancing as a vital solution for high‑traffic systems, explains vertical and horizontal scaling, classifies balancers by hardware, layer and algorithm, and details common algorithms—random, weighted, round‑robin, least‑active, IP‑hash, and consistent hash—with code examples and usage guidance.
This article explains the purpose of the TCP TIME_WAIT state, how it prevents packet loss and connection errors, examines its duration based on the Maximum Segment Lifetime, and analyzes why high‑QPS load testing tools like ab may appear to bypass TIME_WAIT, revealing the impact on server resources.
This guide explains how to troubleshoot firewalld command errors, enable VRRP multicast traffic, and fix VIP migration problems in a Keepalived high‑availability setup on CentOS 7, providing step‑by‑step commands, configuration file adjustments, and verification procedures.
This article explains how traffic packets travel from external IPs or node ports to Kubernetes pods using ExternalIP ClusterIP services, NodePort services, iptables DNAT/SNAT rules, and Calico BGP routing, with step‑by‑step analysis, configuration examples, and command‑line inspections.
This article explains the concepts of blocking and non‑blocking I/O, I/O multiplexing mechanisms such as select, poll and epoll, and the differences between synchronous and asynchronous I/O, then demonstrates Java implementations of BIO, NIO and AIO with sample code.
This guide explains why a Jenkins agent fails to start with the error "provided port: 8182 is not reachable" and provides step‑by‑step troubleshooting methods such as network testing, Docker port mapping verification, and ensuring proper communication between the agent and master nodes.
This article explains Calico’s IPIP networking mode in Kubernetes, detailing its architecture, core components, routing behavior, packet encapsulation, and practical verification through ping tests, route inspection, and packet captures, helping readers understand cross‑node pod communication.
This article examines Calico’s IPIP networking mode in Kubernetes, detailing its architecture, core components, IPIP vs BGP operation, route analysis, packet‑capture findings, and pod‑to‑service communication to illustrate how IP encapsulation facilitates cross‑node traffic.
This guide walks through systematic troubleshooting of Java server problems—including CPU spikes, memory leaks, disk I/O bottlenecks, and network timeouts—by using native Linux tools and JVM utilities such as ps, top, jstack, jstat, iostat, vmstat, and netstat to pinpoint root causes and apply targeted fixes.
This guide lists essential Linux commands for retrieving comprehensive hardware information—including CPU, memory, disk, network interfaces, PCI, USB, SCSI, and BIOS details—along with example outputs and explanations for each category on an Ubuntu 16.04 system.
This article analyzes why Kubernetes pods experience occasional one‑second connect() delays due to SNAT port‑collision issues in the iptables conntrack table, explains the underlying networking mechanisms, and offers practical mitigation techniques such as random‑fully SNAT selection and long‑lived connections.
