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  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

  How does PHP session work?

This article is about how PHP session works internally. Below are the steps : 1. Session in PHP is loaded into PHP core as an extension, we can understand it as an extension. When session extension is loaded, PHP will call core functions to get the session save_handler, i.e interface or functions for reading and writing session data. By default, PHP will handle session data by writing and reading files on the server. But PHP also supplies custom methods for handling session data, we can use sess...

   PHP, session, mechanism     2012-12-28 13:36:49

  Some cases where MySQL cannot be started

After installing MySQL, when we try to start MySQL, sometimes we may not be able to start it. The reasons can be different. We share some general cases where MySQL cannot be started. Case 1: Directory or file permission issue If the permission is set wrongly in MySQL's $datadir and its sub directories or files, MySQL will not be able to read and write files normally. Error message: mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/data /usr/local/mysql/bin/mysqld_safe: lin...

   MySQL,Error,Log     2013-08-15 03:32:36

  5 Ways to Boost MySQL Scalability

There are a lot of scalability challenges we see with clients over and over. The list could easily include 20, 50 or even 100 items, but we shortened it down to the biggest five issues we see.1. Tune those queriesBy far the biggest bang for your buck is query optimization. Queries can be functionally correct and meet business requirements without being stress tested for high traffic and high load. This is why we often see clients with growing pains, and scalability challenges as their site becom...

   MySQL,Scalability,Methods,Implementation,Practice     2011-10-18 02:57:27

  WireGuard VPN Troubleshooting

When you are working as a network/cluster admin for you team to config the WireGuard VPN for other members, you may meet some of the problems below and these are the solution you can try to fix them. ----------------------------------------------------------------------------------------------------------- Problem [1]: The WireGuard handshake request send from the client can be received from the server but the server's response was blocked at some where so the client can not receive serv...

   WIREGUARD,VPN,TROUBLESHOOTING     2021-12-14 09:17:46

  Use DTrace to diagnose gdb issues

A few days ago, I installed the newest 64-bit gdb program (version 7.7.1) on Solaris 10 (X86_64 platform) to debug programs. After playing with the gdb a day, I found 2 issues about gdb:(1) The "set follow-fork-mode child" command doesn't take effect. By default, after the parent process forks the child process, the gdb will track the parent process, so this command can make gdb begin to follow the child process. But this command works OK on Linux.(2) The gdb can't parse the 32-bit application c...

   DTrace, debug, gdb, UNIX     2014-06-28 05:11:20

  Some tricks on PHP session

1. Session timeout problem There is a nuance we found with session timing out although the user is still active in the session.  The problem has to do with never modifying the session variable. The GC will clear the session data files based on their last modification time.  Thus if you never modify the session, you simply read from it, then the GC will eventually clean up. To prevent this you need to ensure that your session is modified within the GC delete time.  You can accomp...

   PHP,Session,Timeout,Solution,Various domain     2015-03-13 07:05:37

  SameSite attribute in cookie

Starting from Chrome 51, a new attribute SameSite has been introduced for browser cookie. This attribute is to prevent CSRF attack. Cookie is normally used to store data exchanged between client and server. It frequently stores user login information. If a malicious website can forge a HTTP request with the valid third party website cookie, it may be called a CSRF attack. For example, if a user logins to a bank website your-bank.com, the bank server responds a cookie: Set-Cookie:id=a3fWa; L...

   JAVASCRIPT,COOKIE,SAMESITE,CHROME,CSRF     2019-09-14 04:57:51

  A New Experimental Feature: scoped stylesheets

Chromium recently implemented a new feature from HTML5: scoped stylesheets, aka. <style scoped>. A web author can limit style rules to only apply to a part of a page by setting the ‘scoped’ attribute on a <style> element that is the direct child of the root element of the subtree you want the styles to be applied to. This limits the styles to affect just the element that is the parent of the <style> element and all of its descendants. Example Here’s a...

   HTML5,Style,Draw,Use case     2012-03-23 12:11:47

  How to apply Domain Level Group Policy

As a system administrator, you may often need to create a Windows domain of a computer network in which all user accounts, computers, printers and other security principals, are registered with a central database (called a directory service). Also one or more domain controllers need to be deployed to enable managing the domain. In this post, we will show you how to apply Domain Level Group Policy. There are lots of posts which have covered how to promote a Windows server to a Domain Controller. ...

   Group Policy,Domain Controller,Account Policy, GPO     2015-03-19 03:46:34