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  Generate certificate with cRLDistributionPoints extension using OpenSSL

In an X509 certificate, the cRLDistributionPoints extension provides a mechanism for the certificate validator to retrieve a CRL(Certificate Revocation List) which can be used to verify whether the given certificate is revoked.   A cRLDistributionPoints extension can contain one or more DistributionPoints where the CRL can be retrieved from. Each DistributionPoint consists of three fields,each of which is optional: distributionPoint : it contains either a SEQUENCE of general...

   X509,OPENSSL,CERTIFICATE,CRLDISTRIBUTIONPOINT,EXTENSION     2015-10-22 03:41:11

  PHP buffer: output_buffering and ob_start

buffer is one piece of memory section, it is usually 4Kb in Linux. It is mainly used between different devices with different speed or different priorities. With buffer, the waiting time between different processes will be reduced. Here is one simple example, when you type something in a text editor, every time when you type a character, the operating system will not write it to the disk directly, instead it will write it to buffer first When the buffer is full, the data in the buffer will be wr...

   PHP buffer,output_buffering,ob_start     2013-06-20 22:54:15

  SIEM Big Data Visualization [04] : Data Transmission Latency SIEM Log Analysis Dashboard

This article will introduce the Data Transmission Latency Log Analysis Dashboard developed for SIEM big data analytics. This is part of the SIEM big data visualization project, if you are interested about other dashboard plug in, you can check below links: SIEM Big Data Visualization [01] : Dashboard for Monitoring Scam Events in Critical Infrastructure SIEM Big Data Visualization [02] : Dashboard for Summarizing SG National Cyber Threats in Critical Infrastructure SIEM Big Data Visualization [...

       2024-11-03 20:49:18

  Convert ext3 to ext4 file system on CentOS

ext3 is a journaled file system that is commonly used by the Linux kernel. It is the default file system for many popular Linux distributions, including Debian. Stephen Tweedie. On June 28, 2006, Theodore Ts'o, the principal developer of ext3, announced an enhanced version, called ext4. Today, we will show how to convert ext3 to ext4 format on CentOS. System environment: Release version : CentOS release 5.4(Final) Kernel:  Linux localhost.lo...

   CentOS, ext3 to ext4     2012-11-21 11:40:45

  Why should we drop or reduce use of MD5?

MD5 is a frequently used one-way hash algorithm, it is commonly used in following situations: Check data integrity. We take hash of the data stored in two different places and compare them. If the hash results are the same, then there is no need to check the actual data. This utilizes the collision-resistant feature. Two different data block will have little chance that their hash values will be the same. Many data service providers use such technique to check repeated data to avoild repeating...

   MD5,Vulnerability,attack     2012-09-29 04:47:49

  Change password of postgres account in Postgres

When installing Postgres on Windows, there is some default account created for user to login. One of them is postgres, but we often don;t know what's the password for this account when we first login using this account. We need to change the password for this account. How to change it? Step 1. Modify the pg_hba.conffile Go to the /data/ and open the pg_hba.conf. # TYPE  DATABASE        USER            ...

   Postgres,password, user account     2013-03-04 01:51:02

  Responsive Web Design

With the popularity of 3G, more and more people are surfing the Internet using mobile phones. Mobile devices are becoming common devices for accessing internet. So web design faces a big challenge which is how to display the same webpage on different devices with different screen  resolutions.Screen resolution of mobile device are usually not very large, the width is below 600px, while PC usually has a resolution over 1000px. It is not an easy task to display the same content with satisfyin...

   CSS,Web design,Layout,Response web design     2012-05-03 06:59:40

  Handling Chinese Character Encoding Issues in Oracle Database

When working with Chinese data in Oracle databases, character encoding issues often lead to garbled text, preventing proper display and processing. This is typically because the default character set in Oracle is US7ASCII, which cannot recognize Chinese characters. By modifying the character sets of the database, client, and application, data can be converted to the correct character set, thus avoiding garbled text issues. This article introduces several methods to resolve Chinese character enco...

   ORACLE,CHINESE CHARACTER,UNICODE,DATABASE     2024-07-12 21:09:14

  OpenLDAP Proxy -- slapd.conf

In the introductory post of OpenLDAP proxy, we mentioned that slapd.conf is the configuration file which tells the slapd service what to do.  Apart from this, there is a dynamic way of configuring slapd where the configurations are stored in LDIF database. In the future, LDIF database will be the one for configuring slapd, the old style of slapd.conf is deprecated. The slapd.conf can be converted to LDIF style using the slapdtest command. slapdtest -f /etc/ldap/slapd.conf -F /etc...

   OPENLDAP,OPENLDAP PROXY,SLAPD,SLAPD.CONF     2017-10-29 04:01:39

  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

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