Manage Basic Networking

1. IPv4 and IPv6 Address Configuration

a. IPv4 Configuration

IPv4 addresses are 32-bit numerical labels used for communication.

Example:

# Set a static IP address
nmcli connection modify conn-name ipv4.addresses "192.168.1.10/24" ipv4.gateway "192.168.1.1" ipv4.dns "8.8.8.8,8.8.4.4" ipv4.method manual

# Activate the changes
nmcli connection up conn-name

b. IPv6 Configuration

IPv6 addresses are 128-bit numerical labels, which allow for a larger address space.

Example:

# Set a static IPv6 address
nmcli connection modify conn-name ipv6.addresses "2001:0db8:85a3:0000:0000:8a2e:0370:7334/64" ipv6.gateway "2001:0db8:85a3::1" ipv6.method manual

# Activate the changes
nmcli connection up conn-name

2. Configuring Hostname Resolution

Hostname resolution is the process of translating hostnames to IP addresses.

Example:

# Set the system hostname
hostnamectl set-hostname myhost.example.com

# Manually add an entry in /etc/hosts
echo "192.168.1.11 anotherhost.example.com anotherhost" >> /etc/hosts

3. Configure Network Services at Boot

Ensuring that network services start automatically helps in maintaining the required connectivity after a system reboot.

Example:

# Ensure NetworkManager starts at boot
systemctl enable NetworkManager

4. Restricting Network Access with firewall-cmd

The firewall-cmd tool manages the firewalld service, which is a dynamic daemon to manage firewall with support for networks zones.

a. Basic Commands

Example:

# List active zones
firewall-cmd --get-active-zones

# Add a service to the public zone permanently
firewall-cmd --zone=public --add-service=http --permanent

b. Advanced Scenarios

Example:

# Block an IP
firewall-cmd --add-rich-rule='rule family="ipv4" source address="192.168.1.123" reject' --permanent

# Allow a specific port range
firewall-cmd --zone=public --add-port=8000-8010/tcp --permanent

Practical Exercise

1. Set a static IP address and hostname for your system.
2. Configure the firewall to only allow HTTP and SSH traffic.

Summary

Networking is a pivotal aspect of system administration. Managing IPv4/IPv6 configurations, ensuring reliable hostname resolution, setting network services to start automatically, and securing network access with firewalld are all essential skills. Effective network management not only boosts system reliability but also enhances security.

Key Points

1. Understanding IP addressing and hostname resolution is fundamental to network configuration.
2. Services like NetworkManager should be enabled at boot to ensure consistent networking.
3. The firewall-cmd tool provides a robust interface for managing network access and restrictions.