Click here for "Error Codes for Commercial Air Conditioners".(Japanese Version)

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LinuxTips(RedHat)_en

Check the port status of Linux

The "IP address" is used to identify which computer on the network you are connecting to, and the "port number" is needed to identify which program running on that computer you are accessing. The port number is a 16-bit integer and ranges from 0 to 65535. To check which ports are waiting for a connection in Linux, use the ss command or netstat command. ●well-known ports Port numbers (0-1023) are reserved in advance for well-known services and protocols used in TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
2020.09.26
LinuxTips(RedHat)_enNetwork Management
LinuxTips(RedHat)_en

Find IP address from hostname

Looking up an IP address from a host name is called "forward DNS lookup". This process can be done by making a query to the name server (DNS) to receive IP address information. ●Use the dig command to find out the IP address. Try to find the IP address of the Yahoo hostname "https://www.yahoo.co.jp/". Check the ANSWER SECTION of the execution result, and you will see the IP address of "https://www.yahoo.co.jp/".
2020.09.26
LinuxTips(RedHat)_enNetwork Management
LinuxTips(RedHat)_en

Look up a mail server by domain name

To find out which host is running as a mail server within a domain, you can check the MX (Mail Exchanger) record set for that domain. In this section we will examine the mailservers for the metro.tokyo.jp domain. From the result of the dig command, you can see that there is a mail server named ml1.tisc.tokyo.jp running in the metro.tokyo.jp domain.
2020.09.26
LinuxTips(RedHat)_enNetwork Management
LinuxTips(RedHat)_en

Display the IRQ of the connected device

Display the IRQ of the connected device The /proc/interrupts file can display IRQ (InterruptReQuest: Interrupt Request) information. There are 16 types of IRQ, ranging from 0 to 15, and the /proc/interrupts file contains information on which ones are used.
2020.09.24
LinuxTips(RedHat)_en
Disk and device management

Display PCI device information

Display PCI device information To check the information of a PCI device in Linux, use the lspci command. This lspci command can be executed with the option "-v" to display more detailed information. You will need super user (root) privileges to run this command.
2020.09.24
Disk and device managementLinuxTips(RedHat)_en
LinuxTips(RedHat)_en

Stop unnecessary services

Linux starts many unnecessary services (programs) that are not used immediately after installation. Services that are not used consume server resources unnecessarily just by being started and running, which is not desirable for security measures. There are two commands to stop services: service and chkconfig, but the service command will cancel the settings and start the stopped service when the server is restarted. Stop the service with the chkconfig command, which will keep the service stopped even after restarting the server.
2020.09.24
LinuxTips(RedHat)_ensystems-management
LinuxTips(RedHat)_en

Include daemon processes in the display

In the case of Linux, there are processes that run specifically for system maintenance without the need to give any instructions. These processes are called daemons, and they wait until there is a request from the user, and when there is a request, they create a new process and execute the process. The process created here is called a child process, and if it is set to run at a certain date and time in advance, it will execute the reserved process at the reserved date and time. Basically, these daemons are executed according to the user's settings, but some of them are default (standard) settings. Since these daemons are not operated by the user in a control terminal such as a console or terminal emulator, they will not be displayed in the control terminal when the ps command is executed, but you can display these processes by adding the option "-x".
2020.09.24
LinuxTips(RedHat)_ensystems-management
LinuxTips(RedHat)_en

Terminate the process

To terminate a running process, use the kill command. You ne...
2020.09.24
LinuxTips(RedHat)_ensystems-management
Rocky Linux 8.4 Building a server

Rocky Linux8.4 : FTP Server

FTP Server Inatall 1. vsftpd Install # dnf -y install vsftpd 2. vsftpd configuration Save the unedited vsftpd.conf with .bak
2021.11.01
Rocky Linux 8.4 Building a server
Rocky Linux 8.4 Building a server

Rocky Linux 8.4 ; Data Backup and Restore

1.Web site data backup 1-1.Backup under /var/www/html ①Create a backup script file [root@Lepard ~]# cd /opt opt]# vi backup_html.sh #!/bin/bash TODAY=`/bin/date +%Y%m%d`
2021.11.01
Rocky Linux 8.4 Building a server
Ubuntu 18.04 Building a server

Ubuntu Server 18.04 ; Obtaining and Installing an Image

Download the installation image The installation media for Ubuntu Server can be downloaded from the official website on the Internet.You will need to create an installation CD/DVD from the downloaded iso file. The download location for the iso file is Ubuntu official download site Install Change the BIOS so that the PC can boot from the installation disk created above, and then boot the PC.
2020.01.28
Ubuntu 18.04 Building a server
Ubuntu 18.04 Building a server

Ubuntu Server 18.04 ; Installing MySQL

Installing MySQL 1.Install the necessary packages. # apt update # apt install mysql-server 2.Configure security settings for MySQL server. There is a tool called mysql_secure_installtion that can be used to configure security-related settings for the MySQL server. When you run it, it will ask you a series of questions to help you configure some security settings.
2020.02.05
Ubuntu 18.04 Building a server
Rocky Linux 8.4 Building a server

Rocky Linux8.4 ; Database installation

1.Mysql8 Installation 1-1.Install [root@Lepard ~]# dnf module -y install mysql:8.0 [root@Lepard ~]# vi /etc/my.cnf.d/charset.cnf　(Create New) # Set the default character encoding # To handle 4-byte characters such as pictograms, use [utf8mb4] [mysqld] character-set-server = utf8mb4 [client] default-character-set = utf8mb4 [root@Lepard ~]# systemctl enable --now mysql 1-2.Security measures
2021.11.01
Rocky Linux 8.4 Building a server
Rocky Linux 8.4 Building a server

Rocky Linux8.4 ; Tripwire, Chkrootkit and Snort installed

1.Tripwire Installation 1.1 Download and install [root@Lepard ~]# cd /usr/local/src src]# wget https://rpmfind.net/linux/epel/8/Everything/x86_64/Packages/t/tripwire-2.4.3.7-5.el8.x86_64.rpm src]# rpm -Uvh tripwire-2.4.3.7-5.el8.x86_64.rpm If you get a dependency error, enter the following
2021.11.01
Rocky Linux 8.4 Building a server
Rocky Linux 8.4 Building a server

Rocky Linux8.4 ; OS Installation

Rocky Linux CentOS, which was positioned as a downstream of RHEL (Red Hat Enterprise Linux), will no longer be supported for CentOS 8 on December 31, 2021. There are three distributions (AlmaLinux, RockyLinux, and CentOS Stream 8) that are attracting attention as a destination for migrating from CentOS, but this time we will build a server using the latest version of RockyLinux 8.4 for the following reasons. CentOS Stream 8 Stability concerns with RHEL upstream Support period until May 31, 2024 AlmaLinux AlmaLinux is a free RHEL clone that is being developed by CloudLinux, the developer of CloudLinux OS, a commercial Linux distribution, with the goal of binary compatibility with the current version of RHEL. Support period until 2029 Rocky Linux It is a free RHEL clone by the project started by Gregory Kurtzer, the founder of CentOS, and is being developed by the community as a "production downstream version of RHEL". The company is also eager to acquire sponsors, including Amazon Web Services (AWS) and Google Cloud. Support period until 2029
2021.11.01
Rocky Linux 8.4 Building a server
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