Debian11.5 Building a server

1.Debian11 Overview In 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 11.5 (codenamed "bullseye"). Released on August 14, 2021 with an update (point release11.5) on September 10, 2022. 2.Download Debian installation image Debian11 download site https://www.debian.org/ Access the above official website and download "debian-11.5.0-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 391 MB for v11.5.0) than a full installer. Click through the following screens in order.

Web server Apache2 installation Allow http:80 and https:443 ports in UFW before installation # ufw allow http # ufw allow https # ufw reload 1 Apache2 Installation and Configuration Apache2 Install 3. Apache2; Using Perl Scripts Enable CGI to make Perl scripts available 4 Apache2 : Using PHP Scripts ①Install PHP # apt -y install php php-cgi libapache2-mod-php php-common php-pear php-mbstring 5. Virtual Host Settings Copy the default configuration file (file name is arbitrary, in this case vhost-yourdomain.conf as an example) and configure the virtual host

1.Install SNORT2 Snort 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. 2.Install Tripwire Implement a system to detect file tampering on Linux servers by crackers. This time, Tripwire, a host-based IDS (IDS=Intrusion Detection System), will be installed as the file tampering detection system. Tripwire creates a database of file status at the time of installation, and detects file additions/changes/deletions by comparing the database with the current status of the file.

1. System Backup 1.1 Backup under /var/www/html ①　Create backup_all.sh script under /opt 1.2 Mysql database backup ①Create db_backup.sh script under /opt # vi /opt/db_backup.sh db_backup.sh script contents 2. System Restore 2.1 Restore backup files under HTML ① Store HTML backup files used for backup in the "/ (root)" directory Select the backup file with the latest timestamp (e.g. www_back_20220501.tar.gz) 2.2 Restore MySQL database ①Save DB backup file to any directory and extract data # cd /var/www/backup/db_bak

1. Obtain a certificate (Let's Encrypt) 1.1 advance preparation ①Enable mod_ssl # a2enmod ssl 2. SSL/TLS (Let's Encrypt) configuration for Apache2 ①Edit Apache2 SSL-related configuration files 3. SSL/TLS (Let's Encrypt) settings on the mail server 3.1 Obtaining a certificate for the mail server Obtain a certificate for the mail server, but it cannot be obtained in the same way as above, so the following with the "--standalone" option fails.

1. Installing and configuring the vim editor Debian 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 package Debian 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

1. Install MySQL 8 1. 1 Install The 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 command 1.2. MySQL Server Security Settings Run the tool mysql_secure_installation to configure security-related settings for the MySQL server. Once executed, several security settings are initiated in the form of questions. First, you will be asked if you want to use a plugin for password validation as follows 2.Install WordPress 2.1 Database Creation Create 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") 2.2 Wordpress Download and Installation ①Download and Deployment

RSA SSH connection with authentication using public key cryptography Create public and private key pairs Create 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. Introduce disk usage check script 1.1 Scripting # cd /opt/script/ # vi disk_capacity_check.sh Contents of disk_capacity_check.sh Configured to notify when disk usage exceeds 80%. 2. Log analysis tool logwatch installed 2.1 logwatch Install # apt -y install logwatch 2.2 Edit logwatch configuration file

1. Antivirus software Clamav installed Install 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. 1.1 Install # apt install clamav clamav-daemon 2. Mail server installation Postfix was developed as a Mail Transport Agent (MTA) to replace sendmail, and is a mail server that is highly compatible with sendmail, secure, easy to maintain, and fast. In addition, since Postfix only functions as an SMTP server for sending mail, the POP server Dovecot for receiving mail will be installed separately in the latter half. 2.1 Postfix : Installation Configuration 3 Applied ClamAV to mail server Postfix Set up Postfix and Clamav to work together to scan incoming and outgoing mail in real time. ①Install Amavisd and Clamav Daemon and start Clamav Daemon

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 iburst pool ntp.nict.jp iburst # Add to the last line (Range for which time synchronization is allowed) allow 192.168.11.0/24 2. Install FTP Server 2.1 Install Vsftpd # apt install vsftpd FTP Port21 allowed # ufw allow ftp # ufw reload

1. SSH Service Security Settings The 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. 2. Firewall Settings Since Debian often uses software called "ufw" to configure firewalls, we will configure firewall settings using ufw. Since ufw is not installed when the OS is installed, the ufw package must be installed prior to configuration. The following is a procedure to configure minimal filter settings after installation. Filter rules to be set in ufw • All packets forwarded to the server are rejected • All packets sent from the server to the outside are allowed • The first port to allow is the port for SSH • Limit packets coming into the server