Symantec Endpoint
Prerequisite 1. Remove the Existing antivirus 2. Get the Proxy info ready 3. Unblock the Error Situation One or more […]
netstat command
The netstat command is a Command Prompt command used to display very detailed information about how your computer is communicating […]
Actual usage of bandwidth
Assumptions The following assumptions have been made when formulating these calculations; No retries, packet losses or other events occur One […]
TCP：三次握手、四次握手、backlog及其他
TCP是什么 首先看一下OSI七层模型： 然后数据从应用层发下来，会在每一层都加上头部信息进行封装，然后再发送到数据接收端，这个基本的流程中每个数据都会经过数据的封装和解封的过程，流程如下图所示： 在OSI七层模型中，每一层的作用和对应的协议如下图所示： 说回TCP，简单说TCP（Transmission Control Protocol）即传输控制协议，是一种面向连接的、可靠的、基于Ip的传输层协议。 TCP协议头部格式 要学习TCP协议，首先得知道TCP协议头部的格式，我在网上找了一张觉得画得比较好的TCP协议头部格式的图片： 这张图把TCP协议头部格式的每部分都描述得比较清楚： Source Port与Destination Port表示源端口与目标端口，各占据2个字节 Sequence Number表示顺序号，占4个字节，每一个字节都有一个序号，连接建立时发送方将初始序号填写到第一个发送的TCP段序号中 Acknowledgment Number表示应答号，占4个字节，是期望收到对方下次发送的数据的第一个字节的序号，也就是期望收到的下一个报文段的首部中的序号 Offset表示数据偏移量，占4位，表示数据开始的地方离TCP段的起始处有多远，实际上就是TCP段首部的长度 Reserved表示保留位，占4位，全为0，为了将来定义新的用途保留 C表示CWR，占1位，拥塞窗口减少标识，发送方设置，用于表明它收到了ECE标识的TCP包，发送端通过降低发送窗口的大小来降低速率 […]
IP virtual-reassembly
While configuring NAT, I will sometimes see “ip virtual-reassembly” added to the NAT interfaces’ configurations: ip nat inside source list […]
install FTP (VSFTPD)
Installing the VSFTPD Linux Server To initiate the installation of the vsftpd package, simply open your CLI prompt and use […]
Use nagios and MRTG to monitor the Cisco Interface usage
PREPARATION In order to compile and use mrtg you need a C compiler and a copy of perl installed on […]
SoftEther VPN-configure
SoftEther is developed as an academic project from University of Tsukuba. Remote user to Company LAN Employees need to connect […]
Protected: SoftEther VPN
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nagios Configuration file
Basic configuration The configuration file is located at /nagios_installation_path/etc/nagios.cfg Log File Format: log_file=<file_name> Example: log_file=/usr/local/nagios/var/nagios.log This variable specifies […]