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Centralized collection of system log, using journald

Step 1 Install system -journal-remote In our environment, the first step will be to install the system-journal- remote package, which will allow us to access these machines remotely. To carry out the installation on our stage machines, we will use the apt package manager in Odin, which runs Debian 12. We will also install the same package in Thor and Loki, which are containers housed within Odin. As for Hela, a Rocky operating system, it will require the use of dnf for installation.

Wednesday, September 20, 2023 | 7 minutes Read
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Disposal of systemd

Systemd and System V (SysV) are two start-up systems used in Linux distributions to manage system and service boot. System V (SysV) is a traditional start-up system that uses shell scripts stored at different running levels (runlevels) to start and stop services sequentially. It was widely used in many Unix and Linux distributions for decades. On the other hand, Systemd is a more modern and advanced start-up system that replaces SysV. Incorporated to improve system start speed and efficiency, systemd uses a unit-based approach and depends on paralleling to start services simultaneously. It also includes additional features such as service management, sockets, timers, and dependencies, making it a more robust and flexible option compared to SysV.

Wednesday, September 20, 2023 | 3 minutes Read
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Install and configure samba in Debian

Samba is a free and open source implementation of the Server Message Block (SMB) protocol, which is used to share files and printers on computer networks. The SMB protocol is a network protocol that allows Windows operating systems to communicate with other network devices, such as file servers, printers and other shared resources. Samba facilitates interoperability between Windows systems and Unix / Linux-based operating systems by allowing Unix systems to share files and resources with Windows systems using the SMB / CIFS protocol. This means that a Samba server can act as a file server for Windows customers, allowing them to access and share files as if they were in a Windows environment.

Wednesday, September 20, 2023 | 2 minutes Read
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Linux task programming commands

The efficient management of programmed tasks is essential for system managers as it facilitates the automatic execution of routine processes. In this context, having a solid set of Linux commands to program and control tasks becomes a fundamental tool. Sleep command The sleep command stops running in the terminal for a specified time interval before returning to the command line. You can indicate the time in seconds, minutes, hours or days. This command is found in the choreutils package.

Wednesday, September 20, 2023 | 5 minutes Read
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SELinux activation configuration

Enable SELinux on a Rocky-based server and make sure that the samba and nfs services work properly with a strict and secure SELinux configuration. Conducts the corresponding access tests. The stage consists of two machines, our server is based on Rocky 9 and our client is a Debian 12. On our server we will have SELinux enabled in enforcing mode. [rocky@rocky-javiercruces ~]$ sestatus SELinux status: enabled SELinuxfs mount: /sys/fs/selinux SELinux root directory: /etc/selinux Loaded policy name: targeted Current mode: enforcing Mode from config file: enforcing Policy MLS status: enabled Policy deny_unknown status: allowed Memory protection checking: actual (secure) Max kernel policy version: 33 We will start by updating the packages needed to configure samba and nfs:

Wednesday, September 20, 2023 | 6 minutes Read
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Apache configuration under debian

Install an Apache web server for use in an Intranet To install the server we must run as root the following command: Create within the / var / www / html directory a file called intrada.html where you put a welcome message Now I’ll put it inside the route: Next we will post a more complete page on our server, for it use your web application website.

Friday, September 8, 2023 | 2 minutes Read
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ARP Protocol

The Address Resolution Protocol (ARP) is fundamental in computer networks to map IP addresses to physical link layer addresses (MAC). Its main function is to find the MAC address associated with a specific IP address on a local network. When one device needs to communicate with another on the same network, it uses ARP to determine the MAC address of the destination before sending data. Do you think the ARP question is a message of dissemination? Make a Wireshark capture of an ARP request and analyze it to justify your response. Yes, it is a message of dissemination as in the header we can see that the destination has a broadcast address. This address is the one that has all its bits at 1 which in the mac addresses is translated into FF:FF:FF:FF:FF:FF.

Friday, September 8, 2023 | 7 minutes Read
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DNS server configuration in Debian

Dnsmasq The dnsmasq package allows you to start a DNS server in a very simple way. Simply by installing and starting the dnsmasq service, without any additional configuration, our PC will become a DNS cache server and will also solve the names we have configured in the / etc / hosts file of our server. The resolution will work both directly and inversely, that is, it will solve the IP given a PC name and the PC name given the IP.

Friday, September 8, 2023 | 3 minutes Read
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FTP under debian

FTP server under debian Installation and configuration of the authenticated proFTPd server First we will create a group called ftpgroup: Create two local users from the ftp group we have created: Jose and Maria We install the ftp service: Basic configuration of the proftpd.conf file: All users access your directory only: We can now access from the browser with users Jose and Maria: Each of these I have created a folder with your name within your personal directories in order to identify them.

Friday, September 8, 2023 | 2 minutes Read
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GNS3 switch configuration

You will learn to configure switches in GNS3, both generic devices and Cisco switches, using the VLans concept to segment the network and explore the complexities of network management. Stage preparation The first thing I’ll do is set up the stage: Customer network configuration Then set up the network cards of the customers, taking advantage that the NAT cloud includes a DHCP server. To do this, we write on the VPCS the following command:

Friday, September 8, 2023 | 11 minutes Read
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Installation GNS3 and Wireshark in Debian

**This post was developed for Debian 11. If you have a more recent version, you can review the Debian 12 post you will find in the network section of the same page. The only part you should not follow if you meet this condition is the installation of GNS3. The rest of the content is still valid. –>

Friday, September 8, 2023 | 19 minutes Read
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Installing and Configuring a DHCP Server on Linux

Configuring the DHCP Server on Debian In this article, you will learn how to configure the isc-dhcp-server. Additionally, we will configure an IP reservation and set it up to operate on two different scopes. Here is my DHCP server’s network configuration: # Router external network auto ens4 iface ens4 inet dhcp # Internal network 1 auto ens5 iface ens5 inet static address 192.168.10.1 netmask 255.255.255.0 # SNAT for ens5 network , ensure that bit of forwarding is activated. post-up iptables -t nat -A POSTROUTING -o ens4 -j MASQUERADE post-down iptables -t nat -D POSTROUTING -o ens4 -j MASQUERADE # Internal network 2 auto ens6 iface ens6 inet static address 192.168.20.1 netmask 255.255.255.0 Installing the isc-dhcp-server To install the DHCP server on Debian, run the following command:

Friday, September 8, 2023 | 4 minutes Read