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1.Remote connection via SSHSSH is a service for connecting remotely to a server and is basically running immediately after the OS is installed, but the default settings are somewhat insecure.Here we will configure the default settings to increase the security of ssh connections.1.1 Edit SSH service configuration fileModify the configuration file to change the SSH service settings.The SSH service configuration file is "/etc/ssh/sshd_config".2.Firewall (firewalld) settingsThe firewall is set to firewalld as default and is enabled during OS installation.2.1 How to use the "firewall-cmd" command to control "firewalld1)Command to check the status and settings of "firewalld"

SSH public key cipher setting1.Create a key pairCreate a public/private key pair for a user connecting to a Linux server using OpenSSH.Use ssh-keygen to create the key pair.The creation of a public/private key pair must be done as a user with remote login privileges.If you do not specify the destination and file name, id_ed25519 and id_ed25519.pub will be created in /home/(user name)/.ssh/. On the way, enter the password for the key.

2. Vsftpd over SSL/TLSLS2.1 Create self-signed certificatesThis work is not required if you are using a trusted, legitimate certificate such as Let's Encrypt.3. File server installation with SambaBuild a file server with access rights that requires user authentication with Samba.Installation Procedure①Create shared folders with access rights that require user authentication②Accessible group creation③Creation of users belonging to accessible groups④Configuration File Editing

1.Apache2 Install , Virtual Host Configuration1.1 Apache2 install①httpd install# dnf -y install httpd1.3 Virtual Host SettingsAssign and configure the domain name [rocky.korodes.com] to the document root [/var/www/html/rocky.korodes.com] directory for virtual host operation2. Use of CGI Scripts①CGI availability check3. PHP installation and configuration1.PHP8 Install4. Digest authentication with Apache2Since Basic Authentication, a well-known authentication authorization method for http, sends authentication information in plain text, there is a risk of ID and password leakage if the packet is intercepted.On the other hand, Digest Authentication encrypts and transmits authentication informa

Clamav (anti-virus software)Install1.Clam AntiVirus InstallMail Server Install1. Postfix1.1 InstallInstall Postfix and build an SMTP serverMail Server : Postfix + Clamav + Amavisd+SpamAssassin1.Real-time scanning of e-mails①Amavisd ,Clamav Server install

1.SSL Certificate Acquisition ( Let's Encrypt )Install the latest open ssl# dnf install openssl-devel1.1 advance preparation1.Package management system Snappy installationSince the SSL certificate issuing tool "certbot" of Let's Encrypt is recommended to be installed using "snap" after 2021, install Snapd first.(Can also be installed the traditional way with dnf or yum)2. Converting Apache to httpsInstall the following# dnf -y install mod_ssl3. SSL/TLS (Let's Encrypt) settings on the mail server3.1 Obtaining a certificate for the mail serverObtain 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.

Mysql8 Install＃dnf module -y install mysql:8.0charset.cnf   Create a new one with the following contentsWordPress Install1. Create database for Word PressAs an example, assume database [wp_db] database user [wp_user] password [?W123456]

Snort3+Snortsnarf InstallImplement Snort, a network-based IDS, in the unauthorized access detection system.SnortSnarf will also be installed to enable the unauthorized access logs extracted by Snort to be checked on a Web browser.RockyLinux8 does not have a Snort3 repository, so build, compile and install Snort3 from source codeAdvance preparation①Install required build tools and librariesInstall the EPEL repository and enable the Powertools repository.chkrootkit①Download and install chkrootkit# cd /usr/local/src# wget ftp://ftp.chkrootkit.org/pub/seg/pac/chkrootkit.tar.gz# tar xvf chkrootkit.tar.gz➁Create /root/bin directory and move chkrootkit command to that directory# mkdir -p /root/bin# mv chkrootkit-0.58b/chkrootkit /root/bin➂Check chkrootkit.

Tripwire1.Install# dnf install -y tripwire2..Passphrase settingSet site passphrase and local passphraseLogwatch①Install# dnf install logwatch -y②Edit configuration fileIntroduce disk usage check script3.1  Script Creation# cd /var/www/system# vi disk_capacity_check.shContents of disk_capacity_check.sh