http://acm.hust.edu.cn/vjudge/contest/view.action?cid=93359#problem/A (456321) http://codeforces.com/problemset/problem/5/A Chat Server's Outgoing Traffic Time Limit:1000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u Submit Status Prac…

A. Chat Server's Outgoing Traffic 题目连接: http://www.codeforces.com/contest/5/problem/A Description Polycarp is working on a new project called "Polychat". Following modern tendencies in IT, he decided, that this project should contain chat as wel…

Chat Server's Outgoing Traffic 点我挑战提目 考察点 模拟 字符串 Time Mem Len Lang 30 0 543 c++ 题意分析 给出类似一个群的即时通讯系统,会有用户的加入和离开,还会有用户发消息,每次用户发消息,都会给当前在聊天室内的用户发送该消息.消息中,每个字符(包括空格)都算一个byte,最后问总共发送了多少byte的消息.保证所有数据的合法. 记录当前聊天室内的人数,然后实时更新,并且处理字符串统计每条消息的字节数,用变量sum=+字节数*人数…

8.7 Explain how you would design a chat server. In particular, provide details about the various backend components, classes, and methods. What would be the hardest problems to solve? 这个简易的聊天服务器功能十分的有限,毕竟只是针对面试题的,谁也无法在面试的有限时间内设计出像QQ那样强大的聊天工具,所以只是实现一些…

原文:https://www.cyberciti.biz/faq/linux-traffic-shaping-using-tc-to-control-http-traffic/ I‘ve 10Mbps server port dedicated to our small business server. The server also act as a backup DNS server and I’d like to slow down outbound traffic on port 80.…

−Table of Contents Journey to the Center of the Linux Kernel: Traffic Control, Shaping and QoS 1 Introduction 2 Motivation 3 The basics of Traffic Control 3.1 First contact 3.2 Netfilter MARK 3.3 Two classes in a tree 3.4 Connecting the marks to the…

Network monitoring on Linux This post mentions some linux command line tools that can be used to monitor the network usage. These tools monitor the traffic flowing through network interfaces and measure the speed at which data is currently being tran…

Prerequisites The only prerequisite is having a Ubuntu 14.04 Droplet established and running. You will need root access to complete this guide. Optional: After completion of this tutorial, It would be a good idea to create a standard user account wit…

作者:vousiu 出处:http://www.cnblogs.com/vousiu 本实例参考自Mike Cantelon等人的<Node.js in Action>一书. server.js 跟前文所说过的原因一样,我认为此处的cache可以不作为参数传进来.此处由于是传引用因此不影响.但若传的是形参则cache的值不是最新的,因为在后一个异步函数加入异步队列时,异步队列中前一个函数还没有运行:等它运行了将cache的值改变了,而后一个异步函数的形参值仍然是旧值,这就将造成多余的读硬盘.…

In reality you probably don’t want to host you websites on your local computer unless you have a very good computer, a very good internet connection and you are an expert system administrator, but this is very useful to learn how the internet works.…

Rocket.Chat 官方给出的文档也个人觉得太麻烦了,并且对ubuntu的支持程度远高于CentOS,自己就折腾写了个安装的笔记,如果是在公司内部或者是部门内部还是很有用处的,比较看中的功能有和gitlab或github的整合,以及注册认证和消息邮件外发 官方文档:https://rocket.chat/docs/installation/manual-installation/centos/ 环境依赖 CentOS6.5 Nginx Mongodb v2 安装步骤 安装Mongodb vi…

  转自:https://www.poeticoding.com/distributed-phoenix-chat-using-redis-pubsub/ In the previous article, Create a High-Availability Kubernetes Cluster on AWS with Kops, we have seen how to create a Kubernetes cluster and how to deploy the Phoenix Chat…

转自:https://www.poeticoding.com/distributed-phoenix-chat-with-pubsub-pg2-adapter/ In this article we’ll see how to cluster the Phoenix Chat nodes, using a really powerful functionality embedded in BEAM (the Elixir/Erlang VM), for easily communicate be…

实际上关于SignalR的介绍网上有很多,这里不做过多赘述,我们来看下官方网站的描述. [摘录自http://signalr.net/] What is ASP.NET SignalR ASP.NET SignalR is a new library for ASP.NET developers that makes it incredibly simple to add real-time web functionality to your applications. What is "rea…

一.部署rocket.chat 1.看官方文档部署,很简单,一步一步跟着部署即可 注意:需要部署节点需要联网主要是yum方式 https://rocket.chat/docs/installation/manual-installation/centos/ 2.这里贴一下步骤 Rocket.Chat in CentOS This installation guide was tested in the following environment: Rocket.Chat OS: CentOS 7…

反弹shell背景: 想要搞清楚这个问题,首先要搞清楚什么是反弹,为什么要反弹.假设我们攻击了一台机器,打开了该机器的一个端口,攻击者在自己的机器去连接目标机器(目标ip:目标机器端口),这是比较常规的形式,我们叫做正向连接.远程桌面,web服务,ssh,telnet等等,都是正向连接. 那么什么情况下正向连接不太好用了呢?1.某客户机中了你的网马,但是它在局域网内,你直接连接不了.它的ip会动态改变,你不能持续控制.2.由于防火墙等限制,对方机器只能发送请求,不能接收请求.3.对于病毒,木马,…

一.知识点介绍: asyncore .asynchat模块使用 由于 Python 是一门带 GIL 的语言,所以在 Python 中使用多线程处理IO操作过多的任务并不是很好的选择.同时聊天服务器将同多个 socket 进行通信,所以我们可以基于 asyncore 模块实现聊天服务器.aysncore 模块是一个异步的 socket 处理器,通过使用该模块将大大简化异步编程的难度.asynchat 模块在 asyncore 模块的基础上做了进一步封装,简化了基于文本协议的通信任务的开发难度.…

Beej's Guide to Network Programming Using Internet Sockets Brian "Beej Jorgensen" Hallbeej@beej.us Version 3.0.15July 3, 2012 Copyright © 2012 Brian "Beej Jorgensen" Hall Contents 1. Intro 1.1. Audience 1.2. Platform and Compiler 1.3. …

  [Docs] [txt|pdf] [draft-ietf-hybi-t...] [Diff1] [Diff2] [Errata] Updated by: 7936 PROPOSED STANDARD Errata Exist Internet Engineering Task Force (IETF) I. Fette Request for Comments: 6455 Google, Inc. Category: Standards Track A. Melnikov ISSN: 207…

Abstract 想要让应用能够躲过硬件故障是一项非常昂贵的任务,因为这通常意味着对软件进行重构,使它包含复杂的恢复逻辑的同时需要部署专用的硬件,而这些对于提升大型的或者遗留的应用的可靠性是巨大的障碍.我们接下来将描述一个通用的高可用服务,它能够为那些已经存在并且未经修改的软件,在其运行的物理机故障的时候,提供保护.Remus提供了非常强的容错能力,它可以在发生故障的时候,让一个正在运行的系统无缝迁移到另一台物理机上,只需要短暂的停机时间,并且完全保留所有的主机状态,例如网络连接等等.我们采用的…

Bonding is the same as port trunking. In the following I will use the word bonding because practically we will bond interfaces as one. Bonding allows you to aggregate multiple ports into a single group, effectively combining the bandwidth into a sing…

Linux comes with a host based firewall called Netfilter. According to the official project site: netfilter is a set of hooks inside the Linux kernel that allows kernel modules to register callback functions with the network stack. A registered callba…

openstack起初的网络部分是和计算核心nova合在一起的,后来被拆分出来,独立成为一个模块, 现在名为Neutron. 本博文是学习记录,记录的是基于GRE tunnel技术的neutron和计算主机之间的连接和通信流程.下面直接上图,结合图做一些简单的介绍(这些介绍的内容,主要来自RDO.) 在介绍上面这个图之前,需要简单的介绍一下,什么是GRE tunnel. GRE(Generic Routing Encapsulation):通用路由封装协议. GRE是VPN的第三层隧道协议,采用…

目前,Neutron有一个QoS的proposal(https://wiki.openstack.org/wiki/Neutron/QoS#Documents),但是只有Ciscso和NVP插件实现了QoS功能,其他插件还未实现.因而,如果想在Neutron中来做网络QoS,还需要额外费些力. 一.基于OVS实现网络QoS 前面的proposal设计和接口都有了,完全可以自己来实现QoS功能: 1. 创建QoS-Rules数据库,写入QoS规则,主键qos_id 2. 创建QoS-Port-Bi…

bonding用的是最简单的负载均衡模式,交换机不需要做配置. https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Installation_Guide/s1-kickstart2-options.html https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide…

PF防火墙 点击认领       PF防火墙 ( 全称:Packet Filter ) 是 UNIX LIKE 系统上进行 TCP/IP 流量过滤和网络地址转换的软件系统.PF 同样也能提供 TCP/IP 流量的整形和控制,并且提供带宽控制和数据包优先集控制. 编辑摘要   更多关于PF防火墙图片   目录 1基本配置 2列表和宏 3表 4包过滤 5网络地址转换N... 6重定向端口转发 7规则生成捷径 8高级配置 9流量整形 10锚定和命名规... 11地址池和负载... 12数据包标记 13…

转载: http://chamibuddhika.wordpress.com/2012/03/21/ssh-tunnelling-explained/ March 21, 2012 by Buddhika Chamith Recently I wanted to set up a remote desktop sharing session from home pc to my laptop. While going through the set up guide I came across…

发现了一个很好的学习Java的外国网站,英语都是很简单的啦,看英语舒服些,关于NIO的系列就直接参照此网站了,而且是英语的! http://tutorials.jenkov.com/ Java NIO (New IO,也有人叫非阻塞IO) is an alternative IO API for Java (from Java 1.4), meaning alternative to the standard Java IO and Java Networking API's. Java NIO…

Martian source / Martian packets In Linux, by default, packets are considered individually for routing purposes. Thus, all the routing algorithm determines where to send a packet based on that packet itself, without taking into consideration that the…

Add-VMNetworkAdapterAclCreates an ACL to apply to the traffic through a virtual machine network adapter.注:只能在Hyper-V主机上添加ACL,无法在VMM服务器上全局添加 Example 1 This example adds an ACL to allow virtual machine Redmond to send to and receive from traffic on IP…