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Creation of public and private key pairsCreate a public/private key pair for a user connecting to the Linux server using OpenSSH.Use ssh-keygen to create key pairs.Creation of public/private key pairs is performed with remote login user 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.

1.FTP Server1.1vsftpd Install# dnf -y install vsftpd1.2vsftpd configurationSave the unedited vsftpd.conf with .bak# cp /etc/vsftpd/vsftpd.conf /home/huong/vsftpd.conf.bak2. vsftpd SSL/TLSConfigure Vsftpd to use SSL/TLS2.1 Create self-signed certificatesThis work is not required if you are using a trusted, legitimate certificate such as Let's Encryp3. 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 Edit

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_ssl2.1 Edit ssl.conf file3. 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 -y install mysql-servercharset.cnf   Create a new one with the fWordPress Install1. Create database for Word PressAs an example, assume database [wp_db] database user [wp_user] password [?W123456]

SuricataSURICATA IDS/IPS is an open source IDS that monitors communications on the network and detects suspicious traffic.The basic mechanism is signature-based, so it can detect predefined unauthorized communications. Suricata is also characterized by its ability to provide protection as well as detection.

SNORT3Snort 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 various attacks such as “buffer overflows,” “stealth port scans,” “CGI attacks,” “SMB probes,” “OS fingerprinting attempts,” “semantic URL attacks,” and “server message block probes. The system can be used to detect a variety of attacks, such as1.advance preparation①Add a CodeReady repository and install the required software

Tripwire1.Download and installation# cd /usr/local/src# wget https://rpmfind.net/linux/epel/8/Everything/x86_64/Packages/t/tripwire-2.4.3.7-16.el8.x86_64.rpm# rpm -Uvh tripwire-2.4.3.7-16.el8.x86_64.rpm2.Passphrase settingSet site passphrase and local passphraseChkrootkitnstall a rootkit detection tool called chkrootkit to check whether a rootkit has been installed on the Linux server.Since chkrootkit is checked using the following command, it is desirable to install it in the early stages after Linux installation, since it is useless after the command itself has been tampered with so that rootkit cannot be detected.[Commands used by chkrootkit]awk, cut, echo, egrep, find, head, id, ls, netstat, ps, strings, sed, uname

1.Website data backup1-1.Backup under /var/www/html①Create backup script file# cd /var/www/system# vi backup_html.sh2.MySQL database backup①Create backup script file# cd /var/www/system# vi db_my_backup.sh3.Restore backup files under html①Store HTML backup files in "/ (root)" directory4.Restore Mysql backup file①Save the database backup file to any directory and（In the example, the directory is "/var/www/backup/db_bak".）Extracting data

SuricataSURICATA IDS/IPS is an open source IDS that monitors communications on the network and detects suspicious traffic.The basic mechanism is signature-based, so it can detect predefined unauthorized communications. Suricata is also characterized by its ability to provide protection as well as detection.

1.Apache2 Install , Virtual Host Configuration1.1 Apache2 install2. Use of CGI Scripts①CGI availability check3. PHP installation and configuration4. 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 information, so there is almost no risk of information leakage.

1.FTP Server1.1vsftpd Install# dnf -y install vsftpd1.2vsftpd configurationSave the unedited vsftpd.conf with .bak# cp /etc/vsftpd/vsftpd.conf /home/huong/vsftpd.conf.bak2. vsftpd SSL/TLSConfigure Vsftpd to use SSL/TLS2.1 Create self-signed certificatesThis work is not required if you are using a trusted, legitimate certificate such as Let's Encryp3. 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 Edit

SSH connection with authentication using public key Creation of public and private key pairsCreate a public/private key pair for a user connecting to the Linux server using OpenSSH.Use ssh-keygen to create key pairs.Creation of public/private key pairs is performed with remote login user 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.

1.Setting up a 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.2.Firewall (Firewalld) settingsIn Oracle, the firewall is firewalld configured by default and enabled during OS installation.To briefly explain "firewalld," when setting communication control policies, communication permission/blocking rules are applied to predefined zones, and these zones are then assigned to each NIC (network adapter).

1.Install bash completion extension package# dnf -y install bash-completion# reboot2.Disabling SELinuxFirst, disable selinux.　selinux is a feature that improves auditing and security in Linux, but when enabled, it can limit the behavior of services and the contents of the configuration considerably.Therefore, it is basically a case of invalidation in many cases.SELinux operating modesEnforcing : SELinux functionality is enabled and access control is enabledPermissive : SElinux will warn, but no access restrictions will be placeddisabled : Both SElinux function and access control are disabled