5.1 Network Configuration

Networking Concepts

graph LR
    Server[Linux Server] -- eth0: 192.168.1.10 --> Switch
    Switch --> Router[Gateway: 192.168.1.1]
    Router --> Internet

• IP Address: Identity (e.g., 192.168.1.10).
• Netmask: Size of network (e.g., /24 or 255.255.255.0).
• Gateway: The exit to the internet (Router).
• DNS: Phonebook (Domain to IP).

View Configuration

Legacy command ifconfig is deprecated. Use ip.

# View IP addresses
ip addr show

# View routing table (Gateway)
ip route show

# View active ports/sockets
ss -tuln

Persistent Configuration

Setting a Static IP changes depending on the OS.

Ubuntu (Netplan)

Edit file in /etc/netplan/00-installer-config.yaml (name varies).

network:
  version: 2
  ethernets:
    eth0:
      dhcp4: no
      addresses:
        - 192.168.1.10/24
      routes:
        - to: default
          via: 192.168.1.1
      nameservers:
          addresses: [8.8.8.8, 1.1.1.1]

Apply with sudo netplan apply.

Rocky Linux (NetworkManager)

Use nmcli (Network Manager Command Line Interface).

# Set Static IP
nmcli con mod "eth0" ipv4.addresses 192.168.1.10/24 ipv4.gateway 192.168.1.1 ipv4.method manual

# Set DNS
nmcli con mod "eth0" ipv4.dns "8.8.8.8"

# Restart Interface
nmcli con up "eth0"