Lesson 8

Red Hat Linux 9.2 (RHEL 9.2), as part of the modern Red Hat Enterprise Linux family, communicates with internal and external networks using advanced and efficient methods compared to the technologies available in the year 2000. Here's an overview of how RHEL 9.2 handles networking today:

1. Networking Tools and Protocols
   • NetworkManager: RHEL 9.2 uses NetworkManager as the primary tool for configuring and managing network connections. This includes both wired and wireless networks, supporting complex setups like VPNs and VLANs.
   • Modern Protocols:
     • IPv4 and IPv6 support for addressing and communication.
     • Enhanced TCP/IP stack with better performance and security.
     • Advanced routing protocols like BGP, OSPF, and MPLS for enterprise networks.
2. Communication with Internal Networks
   • Ethernet and Wi-Fi: Network Interface Cards (NICs), including wired (Ethernet) and wireless (Wi-Fi) adapters, are managed using drivers included in the Linux kernel. These devices allow communication within internal networks, such as local area networks (LANs).
   • Virtual Networking: Support for virtual networking interfaces like `bridge`, `bond`, and `team` devices enables redundancy and load balancing within internal networks.
   • Container and VM Networking: Networking tools like `Podman` or `libvirt` allow seamless communication for containers and virtual machines within an internal network.
3. Communication with External Networks
   • Firewalld: A dynamic firewall daemon that manages access control between internal and external networks. It supports complex rules for network address translation (NAT) and port forwarding.
   • VPN and Tunneling: Supports secure remote communication using protocols like IPsec, OpenVPN, and WireGuard.
   • High-Performance NICs: Integration with high-speed NICs (e.g., 10GbE, 40GbE) ensures low-latency communication with external networks.
4. Communication Hardware
   • Modern Network Adapters: Internal and external network communication relies on high-speed wired (Ethernet) and wireless (Wi-Fi 6) adapters with support for auto-negotiation of speeds and duplex settings.
   • USB Modems and Cellular: While less common, USB modems and cellular network adapters are still supported for connecting to networks via 4G/5G.
5. Software and Configuration
   • Cockpit: A web-based interface included in RHEL 9.2 for managing network configurations, firewalls, and system monitoring.
   • CLI Tools: Tools like `nmcli`, `ip`, `ifconfig` (legacy), and `ethtool` allow administrators to configure and troubleshoot network settings via the command line.
6. Security Enhancements
   • SELinux: Adds mandatory access controls to network services, reducing attack surfaces.
   • TLS/SSL: Secure communication over external networks is ensured through modern encryption protocols.
   • Automatic Updates: Regular updates patch security vulnerabilities in networking components.
7. Cloud and Hybrid Networking
   • RHEL 9.2 integrates with cloud platforms like AWS, Azure, and Google Cloud, providing advanced networking capabilities such as virtual private clouds (VPCs) and hybrid connectivity.

Summary RHEL 9.2 uses advanced software tools, modern hardware interfaces, and robust security mechanisms to facilitate reliable and efficient communication with both internal and external networks. These improvements provide enhanced performance, scalability, and security compared to the methods used in 2000.

During the Dot Com Era, Linux supported communication with other computers over telephone lines and networks. Serial devices such as internal and external modems and non-serial devices, such as network interface cards, actually moved the data from computer to computer. The Linux kernel supported these devices either automatically or via loaded modules.
The setserial command configured and queried serial device characteristics. This program provided a single manipulative interface for a vast range of serial devices, including modems, mice, and serial terminals. The getty program and its variants supported serial communications under Linux. Commonly used protocols over serial lines including PPP and SLIP. Multiple network interface cards (NIC) allowed communication across different networks. The Network Configurator provided an interface for setting up NIC characteristics, such as device, address, gateway, and so on. With multiple network cards configured, a Linux computer could act as a router, bridge, or firewall.

• Learning Objectives which were covered in this module
  Having completed this module, you should be able to:
  1. Describe some of the serial devices supported by Red Hat Linux
  2. Configure and use serial ports
  3. Define a modem's role in a Linux system
  4. Describe the rationale for using multiple network interface cards
  5. Load the correct NIC modules into the kernel to enable multiple network interface cards
  6. Use the Network Configurator tool to enable multiple network interface cards

This module introduced you to the following terms:

1. BIOS: Basic Input and Output System. The BIOS is responsible for providing a standard interface to the computer hardware. An operating system writes to a particular BIOS specification, rather than worrying about the details for all supported hardware.
2. Bridging: Bridges isolate segments of the same network to cut down on overall network traffic.
3. Daemon: A daemon is a program that waits for a request from another program. The daemon then performs the desired action, such as creating an http session, or opening and maintaining a communications socket. Some common daemons include httpd, telnetd, and ftpd.
4. Firewalling: Firewalling protects one network from another. A computer acting as a firewall filters, logs, and audits traffic flowing from one network into the other.
5. IP: Internet Protocol. Usually combined with TCP (Transmission Control Protocol) in order to pass data between a destination and source.
6. Kermit: A communications protocol developed at Columbia University.
7. Modem: A device that allows computers to send data over conventional analong phone lines.
8. PPP: Point-to-Point Protocol. It is used to connect computers with the Internet.
9. Protocol: Protocols identify the type of content communicated. One of the most common protocols is PPP, for communication to and from an Internet Service Provider.
10. Routing: The process of moving information from one network to another. It is very similar to bridging; however, routing works on the network layer.
11. Serial port: A serial port or interface that can be used for serial communication so that one bit of data is transmitted at a time.
12. SLIP: Serial Line Internet Protocol. SLIP is very similar to PPP.
13. Xmodem: Xmodem is a popular file-transfer protocol.
14. Zmodem: Zmodem is similar, but has improved error detection.

Read about what other people are thinking about the use of serial and networking devices with the Linux OS.

Before moving on to the next module, click the Quiz link below to test your understanding of enabling serial and non-serial communications.
Serial Communication - Quiz