Debian11.3 Building a server

1.Debian11 OverviewIn this article, we will explain how to build a server with Debian, the basis of the user-friendly Linux distribution UBUNTU.The latest release is Debian 11.3 (codenamed "bullseye").Released on August 14, 2021 with an update (point release) on March 26, 2022.2.Download Debian installation imageDebian11 download site https://www.debian.org/Access the above official website and download "debian-11.3.0-amd64-netinst.iso." which is convenient for setup in an environment connected to the Internet.（Fits on a single CD）NETINST allows you to download and install the necessary packages from the Internet, so you can use a smaller installer (approximately 378 MB for v11.3.0) than a full installer.Click through the following screens in order.

Web server Apache2 installationAllow http:80 and https:443 p...

RSA SSH connection with authentication using public key cryptographyCreate public and private key pairsCreate a public/private key pair for a user connecting to a Linux server using OpenSSH.Use ssh-keygen to create the key pair.This time, we will create a key set using the RSA cipher used in the SSH protocol Version 2.The creation of a public/private key pair is performed with remote login user privileges (e.g., huong).If you do not specify the destination and file name, id_rsa and id_rsa.pub will be created in /home/huong/.ssh/. On the way, enter the password for the key.

1.1 Backup under /var/www/html①　Create backup_all.sh script under /opt# vi /opt/backup_all.shbackup_all.sh script contents1.2 Mysql database backup①Create db_backup.sh script under /opt# vi /opt/db_backup.shdb_backup.sh script contents2.1 Restore backup files under HTML① Store HTML backup files used for backup in the "/ (root)" directorySelect the backup file with the latest timestamp (e.g. www_back_20220501.tar.gz)2.2 Restore MySQL database①Save DB backup file to any directory and extract data# cd /var/www/backup/db_bak

1. Introduce disk usage check script1.1 Scripting# cd /opt/script/# vi disk_capacity_check.shContents of disk_capacity_check.sh#!/bin/bash#Email Address for NotificationMAIL=" "2. Log analysis tool logwatch installed2.1 Install logwatch# apt -y install logwatch2.2 Edit logwatch configuration file①Copy the default configuration file

1.Install SNORTSnort is an open source network intrusion detection system capable of performing real-time traffic analysis and packet logging on IP networks.It can perform "protocol analysis," "content search," and "matching," and can be used to detect a variety of attacks, including "buffer overflows," "stealth port scans," "CGI attacks," "SMB probes," "OS fingerprinting attempts," "semantic URL attacks," and "server message block probes.

Open source integrated monitoring software "ZabbixZabbix is an open source integrated monitoring software for centralized monitoring of servers, networks and applications. It provides monitoring, fault detection and notification functions required for integrated monitoring. With Zabbix agent and SNMP support for many platforms, you can monitor your entire system with a single Zabbix.To run Zabbix, you will need the PHP programming language, MySQL as a database server, and a web server such as Apache or Nginx. In this article, we will assume that all of these have already been configured.

1. Install MySQL 81. 1 InstallThe MySQL team provides the official MySQL PPA for Debian Linux. After downloading and installing the package on your Debian system, the PPA file will be added to your system. To enable the PPA, run the following command2.Install WordPress2.1 Database CreationCreate a database for Word Press (for example, in this case, the database name is "wp_db", the user name is "wp_user", and the password is "?Y123456y")If you receive a message "Your password does not satisfy the current policy requirements" when creating an account, please make sure your password is at least 8 characters long and includes upper and lower case letters, numbers, symbols, etc.

1. Obtain a certificate (Let's Encrypt)1.1 advance preparation①Enable mod_ssl# a2enmod ssl②Install client tool to obtain Let's Encrypt certificate# apt -y install certbot

1. Antivirus software Clamav installedInstall Clam AntiVirus, a free anti-virus software for Linux, as an anti-virus measure.By installing this anti-virus software, you can not only scan the entire server for viruses, but also scan incoming and outgoing mail for viruses if you build and configure a mail server.

1. Install NTP server# apt -y install chrony# vi /etc/chrony/chrony.conf# Line 8.：Comment the default settings and add the NTP server for your time zone.#pool 2.debian.pool.ntp.org iburstpool ntp.nict.jp iburst# Add to the last line (Range for which time synchronization is allowed)

1. SSH Service Security SettingsThe SSH service allows the root user to log in by default, and since the root user already knows the user name and can log in to the server with administrative privileges once the password is known, we will deny this setting.1.1 Creating a General UserIf you have created a general user when installing Debian, this procedure is not necessary.If the only user created on the server is root, remote login via SSH will not be possible, so if a user has not been created during OS installation, a user must be created in advance.Users can be created with the "useradd" command. The "-m" option creates a home directory and the "-p" option specifies the password.For example, to set "debianuser" as the user account name and "123456" as the password, execute the following

1. Installing and configuring the vim editorDebian has "nano" as the default editor. nano is somewhat difficult to use, and there are few environments where it is used, so we will introduce the procedure for changing the editor to "vim".。1.1 Check vim packageDebian has vim installed by default, but it is a package called "vim-tiny", which is a less functional version. Let's check the installed vim package.Debian uses the "dpkg" command to check packages. The "-l" option displays a list of packages.Since the "dpkg" command as is will show all packages installed on the system, we will use the "grep" command to extract only those packages that contain the string "vim". Execute as follows