Cloud Applications

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

You must have the root permission to run tcpdump-wfile: save the captured packets to the specified file. -Rfile: reads packets from a specified file (Saved by the-w option), instead of capturing packets on the NIC-ccount: specify to capture count

Tcpdump adopts the command line method. its command format is: tcpdump [-adeflnNOpqStvx] [-c quantity] [-F file name] [-I network interface] [-r file name] [-ssnaplen] [-T type] [-w file name] [expression] 1. introduction to tcpdump options-a

The principle of iptablesnat is the same as that of the filter table. The nat table also has three default chains (chains): PREROUTING: the destination DNAT rule redirects external access to other hosts, such as internal SERVER, or DMZ. Because only

When I recently learned about iptable, I found that the configuration will be cleared after restart. Finally, the command for iptables storage is: iptables-save/etc/iptables. up. rule # where you want to save iptables-restore/etc/iptables. up. rules

Data collection and analysis is essential when Linux is a network server, especially a router or gateway. So today, let's take a look at the powerful network data collection and analysis tools in Linux ?? TcpDump. As the name suggests, TcpDump can

#! /Bin/sh # The following are network information about the firewall # internal network adapter: eth1 # internal IP address: 192.168.1.1 # internal subnet mask: 255.255.255.0 # internal network segment: 192.168.1.0/24 # internal Nic: eth0 #

Experiment environment: 1. build an environment to simulate the normal running of server1 Discuz Forum LNMP. the installation process is not discussed in this article, if you are interested, please refer to another blog in this article. 1. create a

In the vim/etc/issue file, you can see the descriptions of the parameters following the "WelcometoLINUX release version name-kernel followed by parameters: \ r: displays the KERNEL version number; \ l: displays the Virtual Console number; \ d:

Introduction: This article is an original article. it shows you how to build a static firewall step by step to protect your computer. at the same time, in each step, I try to tell you how it works. After this tutorial, you will be able to understand

Ethereal uses the libpcap filter language to capture and filter Ethereal. it is explained on the man page of tcpdump, but it is hard to understand, therefore, I will give some further explanations here. Prompt! Some capture filtering examples can be

1. download the file scpusername @ servername:/path/filename from the server, for example, scpusername@192.168.0.10: file name (absolute path) download the file on 192.168.0.10 to the current directory 2. Upload the local file to the server scp/path/

I have mentioned that the newly purchased server of the company uses CentOS5.5. after deploying Tomcat, I found that I entered 114. 80. *. *: 8080 (ip: 8080), but the default Tomcat homepage cannot be displayed. Because it was previously deployed in

When we use the CentOS system, the CentOS firewall sometimes needs to change the settings. The CentOS firewall is enabled by default. you can set the open port of the CentOS firewall as follows: Open the iptables configuration file

Ssh's three powerful port forwarding commands: QUOTE: ssh-C-f-N-g-Llisten_port: DST_Host: DST_portuser @ Tunnel_Hostssh-C-f-N-g-Rlisten_port: DST_Host: DST_portuser @ Tunnel_Hostssh-C-f-N-g-Dlisten_po ssh's three powerful port forwarding commands:

Iptables-F? #-F is the meaning of clearing, the role is to all the chain rules of FILTRETABLE are cleared iptables-AINPUT-s172.20.20.1/32-mstate -- stateNEW, ESTABLISHED, RELATED-jACCEPT # the source address of the INPUT chain matching in the FILTER

If you do not know the basic knowledge about IPTABLES, we recommend that you first check it out. configure a filter table firewall. (1) view the settings of IPTABLES on the local machine [root @ tp ~] # Iptables-L-nChainINPUT (policyACCEPT)

When the NFS service is started, portmapp assigns a dynamic port to each NFS service, such as MOUNTD_PORT, STATD_PORT, LOCKD_TCPPORT, and LOCKD_UDPPORT. How can NFSclient use the NFS service properly when using iptables? The method is to specify the

The loadaverage in the top command is what we often call the system load, that is, the average length of the task queue. When loadaverage is set to 1, the cpu has one task waiting for processing. if the value is lower than 1, the cpu is still idle

I have written an article "iptables details about Cainiao breakthrough". I should be able to understand iptables. But in daily work, you should be careful when setting this, or else you will block yourself out of the door. How can I securely set