RHCSA Practical Lab Series – Network Configuration

CloudNetOps

28 Feb 2025 — 3 min read

Photo by Nathan Dumlao / Unsplash

🔍 Lab 1: Configuring Network Settings in RHEL 9

📌 Objective

Configure node1 with the following network settings:

Hostname: node1.cloudnetops.tech
IP Address: 192.168.250.100
Subnet Mask: 255.255.255.0 (/24)
Gateway: 192.168.250.254
DNS Server: 192.168.250.254

📌 Step 1: Open Virtual Machine Console

Launch your RHEL 9 virtual machine using virt-manager:

[kiosk@foundation0 ~]$ virt-manager

📌 Tip: If using KVM, ensure your virtual machine has a network adapter connected to the correct virtual network.

Username: root  
Password: cloudnetops

📌 Tip: Using a strong password helps improve security, and setting up SSH keys is a better alternative than password authentication.

📌 Step 2: Check Current Network Configuration

Before making changes, identify the active network connection:

[root@clear ~]$ nmcli con show

🔹 Expected output:

NAME                UUID                                  TYPE      DEVICE
Wired connection 1  a2b3c4d5-e6f7-890a-bcde-123456789012  ethernet  enp0s3

This command lists available network connections, including Wired connection 1 or a similar interface.

📌 Tip: The DEVICE column shows the active network interface name, which may vary (e.g., ens192 or enp1s0).

📌 Step 3: Configure Static IP Address

Modify the existing network connection to set a static IP, gateway, and DNS server:

[root@clear ~]$ nmcli con mod 'Wired connection 1' \
    ipv4.method manual \
    ipv4.addresses 192.168.250.100/24 \
    ipv4.gateway 192.168.250.254 \
    ipv4.dns 192.168.250.254 \
    autoconnect yes

🔹 Command breakdown:

ipv4.method manual → Switches from DHCP to manual IP configuration
ipv4.addresses 192.168.250.100/24 → Assigns IP and subnet mask
ipv4.gateway 192.168.250.254 → Configures default gateway
ipv4.dns 192.168.250.254 → Sets DNS server
autoconnect yes → Ensures the connection starts on boot

✅ Best Practice: Use nmcli con show after modification to confirm changes.

📌 Step 4: Apply and Verify Network Configuration

Activate the new configuration:

[root@clear ~]$ nmcli con up 'Wired connection 1'

🔹 Expected output:

Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/2)

🔹 Check if the new IP is assigned correctly:

[root@clear ~]$ ip a

🔹 Expected output (partial):

2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    inet 192.168.250.100/24 brd 192.168.250.255 scope global dynamic noprefixroute enp0s3

🔹 **Test connectivity by pinging the gateway and DNS server:

[root@clear ~]$ ping -c 4 192.168.250.254

🔹 Expected output:

64 bytes from 192.168.250.254: icmp_seq=1 ttl=64 time=0.657 ms
64 bytes from 192.168.250.254: icmp_seq=2 ttl=64 time=0.548 ms

✅ Troubleshooting Tip: If the network doesn’t come up, check /etc/sysconfig/network-scripts/ for interface settings or restart the network:

[root@clear ~]$ systemctl restart NetworkManager

📌 Step 5: Enable SSH and Connect Remotely

Now that networking is configured, try SSH access from foundation0:

[kiosk@foundation0 ~]$ ssh root@192.168.250.100

🔹 Expected output:

root@192.168.250.100's password:
Last login: Thu Mar 28 10:12:34 2024 from 192.168.250.1

✅ If successful, you will be logged into the system.

📌 Step 6: Configure Hostname

To make the hostname persistent:

[root@clear ~]$ hostnamectl set-hostname node1.cloudnetops.tech

🔹 Verify the hostname change:

[root@node1 ~]$ hostname

🔹 Expected output:

node1.cloudnetops.tech

📌 Tip: Ensure that the hostname is reflected in /etc/hosts for proper resolution:

echo "192.168.250.100 node1.cloudnetops.tech node1" >> /etc/hosts

📌 Step 7: Verify Network Configuration & Persistence

1️⃣ Check IP settings:

[root@node1 ~]$ ip a

🔹 Expected output should confirm the correct IP 192.168.250.100/24.

2️⃣ Check hostname:

[root@node1 ~]$ hostnamectl status

🔹 Expected output should display node1.cloudnetops.tech.

3️⃣ Check network connectivity:

[root@node1 ~]$ ping -c 4 8.8.8.8

🔹 Expected output should confirm internet access (if available).

4️⃣ Ensure changes persist after reboot:

[root@node1 ~]$ reboot

After rebooting, confirm that the IP and hostname remain correctly configured.

✅ Final Summary

In this lab, you successfully:
✔ Configured static IP, gateway, and DNS
✔ Enabled and tested network connectivity
✔ Allowed remote SSH access
✔ Set a persistent hostname