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  A serious security vulnerability found in MySQL/MariaDB

Recently a serious security vulnerability was found in MySQL/MariaDB. It relates to the access to the database. The issue is described below.When a user connects to MariaDB/MySQL, a token (SHA over a password and a random scramble string) is calculated and compared with the expected value. Because of incorrect casting, it might've happened that the token and the expected value were considered equal, even if the memcmp() returned a non-zero value. In this case MySQL/MariaDB would think that the p...

   MySQL,MariaDB,bug,fix,password,memcmp()     2012-06-11 10:28:09

  OpenLDAP Proxy -- Installation and configuration

After understanding what the configuration would be for an OpenLDAP proxy, it's time to explain the installation of OpenLDAP proxy and how to make it run. In this post, we will cover how to install OpenLDAP proxy both locally and using docker. Local installation The installation is quite easy, there are a few packages to be installed including the ldap server, ldap client and some utilities. Below steps are for CentOS, the instructions for other platforms should be similar with minor differ...

   INSTALLATION,CENTOS,DOCKER,OPENLDAP,OPENLDAP PROXY     2017-11-03 20:26:41

  Taking Precautions to Avoid Shady VPN Providers

VPNs or virtual private networks are virtual tunnels that obscure your IP address, routing your internet traffic through a server located in a country of your choice, in an encrypted and anonymous way. Using a VPN allows you to: secure your sensitive data from hackers obscure the IP address so you can see content not available in your country avoid websites you routinely surf (e.g., Facebook) noticing a different IP address when you are traveling, and asking you to verify your identity bypass t...

   VPN,NETWORKING     2019-02-19 07:26:26

  Crash your Chrome with %%30%30

Have you ever wondered a simple string can crash one of the most sophisticated designed web browsers -- Chrome? There is a finding from Andris Atteka who found that a null string "%%30%30" appended to an URL can crash Chrome. For example, if you have below URL in your browser address bar or you mouse over below URL, Chrome will crash: http://www.pixelstech.net/%%30%30 When the browser crashed, it may show : Or on Windows, you will see : This bug has been reported to Google at Is...

   CRASH,SECURITY,CHROME,GOOGLE     2015-09-20 08:24:16

  Solve Hibernate "Too many connections" issue in MySQL

When working with Hibernate and MySQL, sometimes some exceptions will be thrown after sometime. The exception may seem like : java.sql.SQLException: Data source rejected establishment of connection, message from server: "Too many connections" This means there are too many active connections on the MySQL, you can use SHOW STATUS LIKE '%Threads_connected%'; to check the active connections to MySQL. If you want to change the maximum connections allowed to MySQL. You can execute: set global max_co...

   MySQL,Hibernate,Clos     2013-09-04 22:20:49

  Why do I need a debugger?

  When I begin to learn a new programming language, I will try and master the debugger for it as early as possible. For example, in 2013, while I touched the Go, there seems only gdb for use. Although gdb itself is not a good choice (From Debugging Go Code with GDB): As a consequence, although GDB can be useful in some situations, it is not a reliable debugger for Go programs, particularly heavily concurrent ones. But at that time there was no other choice. So after delve&nb...

       2017-07-21 22:53:16

  Workaround size limit of phpMyAdmin import sql file

When doing website development with MySQL, we often need to do database backup and restore. For website, the data in database will grow quickly, so when we back up the database, the size of the generated sql file may be over 80MB which is the max allowed size when we want to import a sql file for restoring our database using phpMyAdmin. To workaround this limit, we need to review the documentation of phpMyAdmin. Fortunately, I found an online article written by David Pratt  which gave us a ...

   MySQL,phpMySQLAdmin,80M,import,solution,limit     2014-08-14 09:59:27

  Special ARP Uses: Gratuitous ARP, ARP Probe, and ARP Announce

In an Ethernet environment, all data is ultimately sent in the form of a Layer 2 Ethernet Frame, which includes the Src MAC, Dst MAC, and other headers such as CRC, etc. Ethernet will then deliver the data to the destination. When we program, we often specify the IP and Port, but rarely specify the MAC address. So, how is the Frame sent out? This is done by the operating system. If the system does not know the MAC address corresponding to an IP, it will send a broadcast ARP request (since this r...

   ARP,NETWORK,LINUX     2024-11-07 20:57:26

  Use rsync to delete mass files quickly in Linux

Yesterday I encountered an issue to delete many log files in my Linux workstation, there were around 100,000 files to be deleted. These are log files and they grow very fast, and we need to delete them frequently. Usually we would use rm -rf * to delete these files, but we may need to wait for a relative long time if there are too many files. So we must adopt some unusual way. Fortunately, we can use rsync to delete mass files in one shot. 1. Install rsync yum install rsync 2. Create a new empty...

   rsync,delete file, demo     2012-11-13 10:44:50

  The Problem with Random Numbers

Today, let's talk about how to generate true random numbers. This is an extremely difficult problem, but it involves some very interesting content. First of all, the random numbers provided by programming languages are pseudo-random numbers.  The V8 engine’s official website has an article that particularly reminds everyone of this point. The built-in random numbers are not true random numbers but pseudo-random numbers. Math.random() returns a Number value with po...

   RANDOM NUMBER,TRUE RANDOM,PSEUDO RANDOM,HISTORY     2024-06-21 21:09:14

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