Multi-Boot USB : Ventoy (Open Source)

Ventoy is an open source tool to create bootable USB drive for ISO/WIM/IMG/VHD(x)/EFI files.

With Ventoy, you don't need to format the disk over and over, you just need to copy the ISO/WIM/IMG/VHD(x)/EFI files to the USB drive and boot them directly.

You can copy many files at a time and Ventoy will give you a boot menu to select them. You can also browse ISO/WIM/IMG/VHD(x)/EFI files in local disks and boot them.

Supports x86 Legacy BIOS, IA32 UEFI, x86_64 UEFI, ARM64 UEFI and MIPS64EL UEFI. Most types of OS supported (Windows/WinPE/Linux/ChromeOS/Unix/VMware/Xen etc.)

Official Ventoy Website : https://www.ventoy.net/en/index.html

!!! HAPPY COMPUTING !!!

Install : CentOS Server v.7.0

 How To Install CentOS Server v.7.0 with basic configurations and update repositories.

Command Used:

• sudo yum update
• sudo shutdown now -h

!!! HAPPY COMPUTING !!!

Zabbix : Install Zabbix-Agent in CentOS

 1. sudo rpm -Uvh https://repo.zabbix.com/zabbix/6.0/rhel/7/x86_64/zabbix-agent-6.0.3-1.el17.x86_64.rpm

* Check for latest version in https://repo.zabbix.com/zabbix.

2. sudo yum update

3. sudo yum install zabbix-agent -y

4. sudo nano /etc/zabbix/zabbix-agentd.conf

        --> Server = [Zabbix Server IP Address]

        --> Hostname = [CentOS hostname]

5. sudo iptables -A INPUT -p tcp -s [Zabbix server IP address] --dport 10050 -m state --state NEW,ESTABLISEHD -j ACCEPT

* If "firewalld" was install, add port 10050 into exception list.

6. sudo systemctl restart zabbix-agent

7. sudo systemctl enable zabbix-agent

8. sudo systemctl status zabbix-agent

9. Continue to add client host into Zabbix server via browser, select --> CentOS with Zabbix Agent

CentOS v.7 : Apache Guacamole

 Apache Guacamole is a RDP to HTTP/HTTPS open source remote broker/gateway.

1. Install CentOS v.7.0 with Minimal Installation, follow all on-screen configurations accordingly.

2. During the install, configure the IP Address to Fixed/Manual and the hostname (eg. guacsvr).

3. Install the RPM Fusion repository :-

• sudo yum install -y epel-release
• sudo yum -y localinstall --nogpgcheck https://download1.rpmfusion.org/free/el/rpmfusion-free-release-7.noarch.rpm https://download1.rpmfusion.org/nonfree/el/rpmfusion-nonfree-release-7.noarch.rpm

4. Install some utilities :-

• sudo yum install -y nano net-tools wget

5. Install MariaDB, Tomcat & Apache Guacamole dependencies :-

• sudo yum install -y cairo-devel libjpeg-turbo-devel libwebsockets-devel libpng-devel uuid-devel ffmpeg-devel freerdp-devel pango-devel libssh2-devel libvncserver-devel pulseaudio-libs-devel openssl-devel libvorbis-devel libwebp-devel libtool libtelnet-devel freerdp mariadb-server tomcat

6. Download, Extract & Make Apache Guacamole Server (as of writing the latest version is 1.3.0, check for latest version at https://downloads.apache.org/guacamole/) :-

• sudo wget https://downloads.apache.org/guacamole/1.3.0/source/guacamole-server-1.3.0.tar.gz
• sudo tar -xzf guacamole-server-1.3.0.tar.gz
• sudo wget https://downloads.apache.org/guacamole/1.3.0/binary/guacamole-1.3.0.war
• cd guacamole-server-1.3.0
• sudo ./configure --with-init-dir=/etc/init.d
• sudo make install
• sudo ldconfig && cd ~
• cp ~/guacamole-1.3.0.war /var/lib/tomcat/webapps/guacamole.war
• sudo firewall-cmd --permanent --add-port=8080/tcp
• sudo firewall-cmd --reload
• sudo systemctl enable tomcat && systemctl enable mariadb && systemctl enable guacd

7. Download & Install Connector, Extensions & Lib :-

• sudo mkdir -p /usr/share/tomcat/.guacamole/{extensions,lib}
• sudo wget https://cdn.mysql.com//Downloads/Connector-J/mysql-connector-java-8.0.24.tar.gz
• sudo tar -xzf mysql-connector-java-8.0.24.tar.gz
• cp mysql-connector-java-8.0.24/mysql-connector-java-8.0.24.jar /usr/share/tomcat/.guacamole/lib/

Extensions (select whichever you preferred) :-

• sudo wget https://downloads.apache.org/guacamole/1.3.0/binary/guacamole-auth-jdbc-1.3.0.tar.gz
• sudo wget https://downloads.apache.org/guacamole/1.3.0/binary/guacamole-auth-ldap-1.3.0.tar.gz
• sudo tar -xzf guacamole-auth-jdbc-1.3.0.tar.gz
• sudo tar -xzf guacamole-auth-ldap-1.3.0.tar.gz
• cp guacamole-auth-jdbc-1.3.0/mysql/guacamole-auth-jdbc-1.3.0.jar /usr/share/tomcat/.guacamole/extensions/
• cp guacamole-auth-ldap-1.3.0/guacamole-auth-ldap-1.3.0.jar /usr/share/tomcat/.guacamole/extensions/
• sudo systemctl start mariadb && systemctl start tomcat

8. To secure MySQL server configurations :-

• sudo mysql_secure_installation
• Enter
• Key-in your new password
• When prompted = Yes, Yes, Yes, Yes

9. Configure MySQL DB :-

• sudo mysql -u root -p
• CREATE DATABASE IF NOT EXISTS guacdb DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
• GRANT SELECT,INSERT,UPDATE,DELETE ON guacdb.* TO 'guacuser'@'localhost' IDENTIFIED BY 'guacpass' WITH GRANT OPTION;
• flush privileges;
• quit

10. Install Apache Guacamole Client :-

• sudo wget https://downloads.apache.org/guacamole/1.3.0/source/guacamole-client-1.3.0.tar.gz
• sudo tar -xzf guacamole-client-1.3.0.tar.gz
• sudo cat guacamole-client-1.3.0/extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/schema/*.sql | mysql -u root -p guacdb
• sudo mkdir -p /etc/guacamole

Create and configure guacamole properties :-

• sudo nano /etc/guacamole/guacamole.properties
• #MySQL properties
• mysql-hostname: localhost
• mysql-port: 3306
• mysql-database: guacdb
• mysql-username: guacuser
• mysql-password: guacpass
• #Additional settings
• mysql-default-max-connections-per-user: 0
• mysql-default-max-group-connections-per-user: 0
• sudo chmod 0400 /etc/guacamole/guacamole.properties
• sudo chown tomcat:tomcat /etc/guacamole/guacamole.properties
• ls -alh /etc/guacamole/
• ln -s /etc/guacamole/guacamole.properties /usr/share/tomcat/.guacamole/
• sudo chown tomcat:tomcat /var/lib/tomcat/webapps/guacamole.war

11. Configure Time Zone for MySQL :-

• sudo nano /etc/my.cnf
• default-time-zone='+8:00'

12. Configure the Connector :-

• sudo setsebool -P tomcat_can_network_connect_db on
• sudo restorecon -R -v /usr/share/tomcat/.guacamole/lib/mysql-connector-java-8.0.24.jar

13. Restart the server.

• sudo shutdown now -r

14. On another computer, open any internet browser

• http://[Server IP]:8080/guacamole
• Username = guacadmin
• Password = guacadmin

! Important to change the password !

CentOS v.7 : List Existing User & Login History

To get User Listing.

 [root@server~]# get ent passwd

OR

[root@server~]# less /etc/passwd

OR

[root@server~]# cut -di -f1 /etc/passwd

To get Login History.

[root@server~]# last -120

OR

[root@server~]# cat /var/log/secure         *The "secure" file may have corresponding date.

CentOS v.7 : Enabled/Disabled GUI at Boot-up

 CentOS v.7.0 : Enabled/Disabled GUI from Boot-up.

Enabled

1. systemctl get-default
2. systemctl set-default graphical.target
3. startx

Disabled

1. systemctl isolate graphical.target
2. systemctl set-default multi-user.target