Cloud Applications

After iptables is set, ftp cannot be accessed normally. the solution sets iptables to prohibit all ports. only after the policy is accessed, ftp cannot be accessed normally in most cases, because ftp has two active and passive connection modes, a

After a web server is built on a virtual machine, the host cannot be accessed, as shown in the following figure: 1. The local machine can ping Virtual Machine 2. The VM can also ping the host 3. Virtual machines can access their own web4. The reason

Next, I will add multiple IP addresses to a friend's machine in the evening. next I will record how to add multiple IP addresses to Centos. if you need to know more, please refer. Log on to SSH: vi/etc/sysconfig/network-scripts/ifcfg-eth0: 0 Second

The iptables-AINPUT-ptcp-s10.1.2.187-jACCEPT adds 10.1.2.187 to the permitted range iptables-tnat-APOSTROUTING-jSNAT -- to-source10.1.2.1 parameter --- A: add (with link)-I: insert-p: with protocol-s: source ip-d: Target IP-j: Operation behavior-t:

Some servers need to deny access from IP addresses in specific countries. you can use Iptables with ipdeny to Filter IP segments from different countries as the source. a large number of IP segments may affect iptables performance, you can also use

Function description: dumping network transmission data. Syntax: tcpdump [-adeflnNOpqStvx] [-c packet count] [-dd] [-ddd] [-F expression file] [-I network interface] [-r packet file] [-s data packet size] [-tt] [-T data packet type] [-vv] [-w data

When using the TCP protocol for network communication, the two sides of the communication first need to establish a connection link. of course, this does not mean that the "connection link" is not required for UDP communication ", the connection

Nagios is a monitoring system that monitors system running status and network information. Nagios can monitor specified local or remote hosts and services, and provide exception notification functions. Nagios can run on Linux/Unix platforms and

After CentOS is installed, only port 22 is enabled by default. if you want to open other ports, you need to open the required ports. For example, open the default port 80 for http edit iptablesvi/etc/sysconfig/iptables

This section describes iptables concepts and usage instructions in iptables, which must be case sensitive. The main syntax differences between ipchains and iptables are as follows: 1. in ipchains, for example, the input chain uses lower-case chains.

In the previous blog, I explained some common knowledge about iptable. here I will repeat the linux firewall with two parts, they are netfilte in the kernel space and iptables in the user space, while iptable can define four types of rules: filter:

Some time ago, because I had to write a router program myself, I began to learn libpcap and netlink. I also read articles written by many cool people on the Internet, we found that the pcap and netlink materials in Chinese are quite few (in

The command to disable the firewall in Linux. today, I want to take a break from the ssh remote connection port on the LInux server for security purposes, I added a line of port8081 to the sshd_config file, but after the configuration is completed

Functions of the text editor: 1. create or modify a text file 2. maintain the classification of various configuration file text editors in linux: line editor and full screen editor, character interface editor and graphical interface editor the most

The file/etc/fstab contains static file system information and defines how storage devices and partitions are integrated into the entire system. The mount command reads the file and determines the mounting options for the device and partition. File

Kaiwii summarized my own experience in using vi or vim: First, move the cursor up and down: of course, use the arrow keys on the keyboard. (ps: What r, it is a pain to use vi. why should we remember so many commands ?) Simply remember one. press the

Basic operations for apache startup, stop, and restart commands in linux: This document assumes that your apahce installation directory is/usr/local/apache2. these methods are suitable for www.2cto in any situation. comapahce startup command:

Shell command execution sequence control [plain] www.2cto.com & amp; Command 1 & amp; Command 2: If this command is successfully executed & amp; then execute this command. [Development]/usr/xxxx/ytcclb & gt; ls-ltest.sql-rwxr -- r -- 1xxxxgroup225...

Shell command to read data and output data [plain] www.2cto. comshell scripts read data in several ways: 1. keyboard Input. default value: 2. read from file 3. the echo function is passed through pipeline commands: \ c: No line feed \ f: paper feed \

Linux cluster principle and installation configuration we have a lot of problems to solve when using a Linux cluster. In fact, the most important problem is the understanding and installation process of the principle of the Linux cluster. Here we