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  Difference between localhost and 127.0.0.1

Lots of people would think what the address 127.0.0.1 is when first seeing this address. In fact, 127.0.0.1 is a loopback address which refers to the local machine. It is generally used for local testing. When typing ping 127.0.0.1 on local command console, it will send network packets to local IP/TCP layer to test whether IP/TCP works properly or not.  To those who are used to use localhost, it is actually mapped to 127.0.0.1 by default. There are hosts files in the system which store this...

   LINUX,NETWORK,LOCALHOST,127.0.0.1,LOCALHOST VS 127.0.0.1     2018-09-29 22:11:12

  Handle NXDomain error when resolving IP address in Ruby DNS resolver

In another post, we covered how to resolve SystemStackError when resolving IP address in Ruby. In this post, we would cover another common issue where a NXDomain error is returned when resolving an IP address. The NXDomain error means that the queried domain name does not exist in the DNS. In Ruby, DNS resolver library will use /etc/resolv.conf by default get the name servers to resolve the domain name. There are multiple DNS name servers can be specified in /etc/resolv.conf with below format. ...

   RUBY,RUBY ON RAILS,NETWORK,DNS,NXDOMAIN     2017-07-16 01:39:23

  Smuggling data in pointers

While reading up on The ABA Problem I came across a fantastic hack.  The ABA problem, in a nutshell, results from the inability to atomically access both a pointer and a "marked" bit at the same time (read the wikipedia page).  One fun, but very hackish solution is to "smuggle" data in a pointer.  Example:#include "stdio.h"void * smuggle(void * ptr, int value){  return (void *)( (long long)ptr | (value & 3) );}int recoverData(void * ptr){  return (long long)ptr &...

   C,Pointer,Bit,Data,Atomic,Smuggle     2011-11-14 08:15:59

  Can two new objects point to the same memory address in GoLang?

Do you have any idea what the output will be for below GoLang snippet? package main import ( "fmt" ) type obj struct{} func main() { a := &obj{} fmt.Printf("%p\n", a) c := &obj{} fmt.Printf("%p\n", c) fmt.Println(a == c) } Many people would think that a and c are two different object instances which have different memory addresses. Hence a == c will be false. But if you try to run the above program, you would see below output 0x5781c8 0x5781c8 true To get to know the reason wh...

   GO,GOLANG,VARIABLE ESCAPE,ZEROBASE     2019-04-06 01:19:52

  Create host only network on VirtualBox

Previously we showed how to install Ubuntu in VirtualBox. What if we want to communicate with the host OS from within the Guest OS on VirtualBox? There are a few ways to do this. For example, bridged network, Host only networks. Today we will show you how to enable network communication between host OS and guest OS using host only networks. A host only network will not need to access the physical network interface of the host OS. It will create a network between different virtual machines and th...

   VIRTUALBOX,NETWORK,VIRTUAL MACHINE,HOST-ONLY     2015-12-01 09:29:13

  How can you test if your VPN is working properly?

Installing a VPN on your device is one of the essential steps you need to take in order to have a safe and pleasant online experience. It good functioning is in your best interest and this is why you need to make sure that your VPN is working properly. Unfortunately, a lot of problems can occur if it turns out that your VPN is not up to the task and that it has some leaks.  Can a leak really occur? To answer you most directly – Yes! Yes, it can! Unfortunately, no system is perfect an...

   VPN     2020-09-17 06:53:19

  How Do I Enable Remote Access To MySQL Database Server?

By default remote access to MySQL database server is disabled for security reasons. However, some time you need to provide remote access to database server from home or a web server. If you want to remotely access to the database server from the web server or home, follow this quick tutorial.MySQL Remote AccessYou need type the following commands which will allow remote connections.Step # 1: Login Using SSH (if server is outside your data center)First, login over ssh to remote MySQL database ser...

   MySQL,Remote access,Enable,Host or webdomain     2011-10-31 00:31:41

  Get Facebook, Twitter and YouTube back

Facebook, Twitter and YouTube have become part of many people's daily network life. People hang around these sites to network with known and unknown friends, to know about the latest news and to relax with fancy video clips. But what will you feel if all of a sudden you cannot access them? Want to experience this? Go behind the GFW(Great Firewall) of China. Just a joke, but it's real. Huh, you are out of China? Don't worry. Change your DNS server to those located in China. I just experienced it,...

   DNS spoofing, GFW, YouTube, 37.61.54.158     2014-12-20 21:41:34

  Install and setup vsftpd on AWS server

When developing websites, frequently we may need to upload source codes to the remote server. To ease of thew work, many website developers set up FTPs to upload the files. This post is a tutorial on how to install and setup vsftpd on a server. vsftpd is a very popular FTP service on Unix-like systems. Open command terminal, then install the vftpd by issuing command yum install vsftpd or sudo apt-get install vsftpd After installing the vsftpd, the config file needs to be updated based on the ope...

   FTP,vsftpd,AWS,Passive,Active     2015-02-02 02:20:27

  The 10 most expensive domains on the Internet

Domain name is the name which we usually type on the web browser address bar. For example, we may type http://www.apple.com on the address bar, here www.apple.com is the domain name. Can you imagine that this domain is worth millions of dollars? We believe that most domains are initially for starting related business and easy for users to remember. But with the popularity of the business, some of the domains become valuable and they are more expensive than some small companies. Below are some mo...

   Domain name,Price     2013-01-01 10:32:06

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