it-knowledge/src/solutions/networking.md

Network Solutions [🌐]

This section documents my solutions to networking scenarios, including network configuration, troubleshooting, and security.

Scenario Tags

Tag	Description
[v1-S7]	Network Configuration - Practice Scenarios v1
[v2-S7]	Network and Storage Troubleshooting - Practice Scenarios v2
[v3-S7]	Network Services Configuration - Practice Scenarios v3

Scenario: [v1-S7] Network Interface Configuration

Original Problem

From Practice Scenarios v1, Scenario 7:

1. Configure static IPv4 address: 192.168.1.100/24
2. Configure static IPv6 address: 2001:db8:1234:5678::100/64
3. Set hostname to 'rhcsa.example.com'
4. Configure DNS resolution using /etc/resolv.conf
5. Implement network access restrictions using firewalld zones

Environment

• OS Version: RHEL/Rocky Linux 8.x
• Initial State: DHCP-configured network interface
• Required Outcome: Properly configured static network settings with hostname and firewall zones

Solution Steps

1. Check Current Network Configuration

   # Check network interfaces
   ip addr show
   
   # Check routing
   ip route show
   

   The first step is to identify the current network configuration to understand what needs to be changed.

2. Configure Static IPv4 and IPv6 Addresses

   # Configure static IPv4 address
   sudo nmcli connection modify eth0 ipv4.addresses 192.168.1.100/24 ipv4.method manual
   
   # Configure static IPv6 address
   sudo nmcli connection modify eth0 ipv6.addresses 2001:db8:1234:5678::100/64 ipv6.method manual
   
   # Set default gateways
   sudo nmcli connection modify eth0 ipv4.gateway 192.168.1.1
   sudo nmcli connection modify eth0 ipv6.gateway 2001:db8:1234:5678::1
   

   This configures the static IP addresses on the network interface.

3. Set Hostname

   # Set hostname
   sudo hostnamectl set-hostname rhcsa.example.com
   
   # Update /etc/hosts
   sudo echo "127.0.0.1 rhcsa.example.com rhcsa" >> /etc/hosts
   

   This sets the system hostname and updates the hosts file.

4. Configure DNS Resolution

   # Configure DNS servers
   sudo nmcli connection modify eth0 ipv4.dns "8.8.8.8 8.8.4.4"
   
   # Apply changes
   sudo nmcli connection up eth0
   

   This configures the DNS servers and applies all the network configuration changes.

5. Configure Firewall Zones

   # Create a new zone for restricted access
   sudo firewall-cmd --permanent --new-zone=restricted
   
   # Add services to the zone
   sudo firewall-cmd --permanent --zone=restricted --add-service=ssh
   sudo firewall-cmd --permanent --zone=restricted --add-service=http
   
   # Add source network to the zone
   sudo firewall-cmd --permanent --zone=restricted --add-source=192.168.1.0/24
   
   # Reload firewall
   sudo firewall-cmd --reload
   

   This sets up a new firewall zone that restricts access to only SSH and HTTP from the local network.

Verification

# Verify IP configuration
ip addr show

# Verify hostname
hostname

# Verify DNS resolution
dig google.com

# Verify firewall zones
sudo firewall-cmd --list-all-zones

Key Learnings

• Network configuration with NetworkManager
• IPv4 and IPv6
• Firewall zone management
• DNS configuration

Skills Demonstrated

• Network Configuration
• DNS Management
• Network Troubleshooting
• Network Security

Scenario: [v2-S7] Network and Storage Troubleshooting

Original Problem

From Practice Scenarios v2, Scenario 7:

1. Diagnose and repair failed NFS mounts
2. Recover from a failed LVM configuration
3. Fix network connectivity issues
4. Restore correct SELinux contexts after file restoration
5. Configure autofs for user home directories
6. Set up network teaming for redundancy

Environment

• OS Version: RHEL/Rocky Linux 8.x
• Initial State: System with various network and storage issues
• Required Outcome: Fully functional system with resolved issues and properly configured network

Solution Steps

[To be filled when I complete this exercise]

Scenario: [v3-S7] Network Services Configuration

Original Problem

From Practice Scenarios v3, Scenario 7:

1. Configure network with:
   • Bonded interface with active-backup
   • VLAN configuration
   • Static routes
2. Set up DNS resolution with:
   • Multiple DNS servers
   • Search domains
   • Local host entries
3. Implement network security with:
   • TCP Wrappers
   • IPtables rules
   • Fail2ban configuration

Environment

• OS Version: RHEL/Rocky Linux 8.x
• Initial State: Basic network configuration with single interface
• Required Outcome: Advanced network configuration with bonding, VLANs, and security features

Solution Steps

[To be filled when I complete this exercise]