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SNORT3  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 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 as

1.Disabling SELinux First, disable selinux. selinux is a feature that improves auditing and security in Linux, but when enabled, it places considerable restrictions on the behavior of services and on what can be configured. Therefore, it is basically disabled in many cases. SELinux operating modes Enforcing : SELinux functionality is enabled and access control is enabled Permissive : SElinux will warn, but no access restrictions will be placed disabled : Both SElinux function and access control are disabled 2.System Modernization Package updates are performed as soon as possible immediately after OS installation. However, when a dnf update is performed, a kernel update is also performed at the same time. A kernel update may require rebooting the system or stopping services, or worse, a kernel panic may occur and the system may not boot. It is wiser to exclude the kernel from the update. The kernel can be excluded from updates by running dnf -y update with "--exclude=kernel*" after it.

1.Remote connection via SSH SSH 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 file Modify the configuration file to change the SSH service settings. The SSH service configuration file is "/etc/ssh/sshd_config". 2.Firewall (firewalld) settings The firewall is set to firewalld as default and is enabled during OS installation. 4.NTP Server Build an NTP server to synchronize the server time with Japan Standard Time

SSH connection with authentication using public key cryptography  Creation of public and private key pairs Create 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 Server 1. 1 Vsftpd Install # dnf -y install vsftpd 1.2 Configure Vsftpd Save the unedited vsftpd.conf with .bak 3. File server installation with Samba Build a file server with access rights that requires user authentication with Samba. Installation Procedure ①Create shared folders with access rights that require user authentication ②Accessible group creation ③Creation of users belonging to accessible groups ④Configuration File Editing

1.Apache2 Install , Virtual Host Configuration 1.1 Apache2 install ①httpd install # dnf -y install httpd 1.3 Virtual Host Settings Assign and configure the domain name [rocky.korodes.com] to the document root [/var/www/html/rocky.korodes.com] directory for virtual host operation 2. Use of CGI Scripts ①CGI availability check 3. PHP installation and configuration 1.PHP8 Install 4. Digest authentication with Apache2 Since 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] Install 1.Clam AntiVirus install # dnf -y install clamav clamd clamav-update 2.Clam AntiVirus  Configuration File Edit Mail Server Install 1. Postfix 1.1 Install Install Postfix and build an SMTP server Mail : Postfix + Clamav + clamav-milter+SpamAssassin 1.Real-time scanning of e-mails ①clamav-milter Install Virus checks are performed on the mail server side using Clam AntiVirus. The mail server and Clam AntiVirus are linked using clamav-milter.