Linux Automatic Network Configuration

linux_automatic_network_config.sh

#!/bin/bash

# Check if all arguments are provided
if [ $# -ne 6 ]; then
    echo "Usage: $0 <ipv4> <cidr/subnet-mask> <gateway> <dns1> <dns2> <mac-address>"
    exit 1
fi

IPV4=$1
CIDR=$2
GATEWAY=$3
DNS1=$4
DNS2=$5
MACADDR=$6

# Check if apt (Debian-based) or dnf (RHEL-based) exists
if command -v apt >/dev/null 2>&1; then
    # Detect interface name by MAC address (Debian-based systems)
    INTERFACE=$(ip -o link | grep -i "$MACADDR" | awk -F':' '{print $2}' | tr -d ' ')

    if [ -z "$INTERFACE" ]; then
        echo "Error: No interface found with MAC address $MACADDR"
        exit 1
    fi

    echo "Detected Debian-based system (apt exists), using interface: $INTERFACE"

    # Create the Netplan configuration
    cat <<EOF > /etc/netplan/01-netcfg.yaml
network:
  version: 2
  ethernets:
    $INTERFACE:
      dhcp4: no
      addresses: [$IPV4/$CIDR]
      gateway4: $GATEWAY
      nameservers:
        addresses:
          - $DNS1
          - $DNS2
      match:
        macaddress: $MACADDR
      set-name: $INTERFACE
EOF

    # Apply the network configuration
    netplan apply

    echo "Network and DNS configuration applied permanently on Debian-based system."

elif command -v dnf >/dev/null 2>&1; then
    # Detect interface name by MAC address (RHEL-based systems)
    INTERFACE=$(ip -o link | grep -i "$MACADDR" | awk -F':' '{print $2}' | tr -d ' ')

    if [ -z "$INTERFACE" ]; then
        echo "Error: No interface found with MAC address $MACADDR"
        exit 1
    fi

    echo "Detected RHEL-based system (dnf exists), using interface: $INTERFACE"

    # Determine subnet mask from CIDR
    SUBNET_MASK=$(ipcalc -m $IPV4/$CIDR | grep -w 'NETMASK' | cut -d '=' -f 2)

    # Backup current configuration if it exists
    if [ -f /etc/sysconfig/network-scripts/ifcfg-$INTERFACE ]; then
        cp /etc/sysconfig/network-scripts/ifcfg-$INTERFACE /etc/sysconfig/ifcfg-$INTERFACE.bak
        echo "Backup of existing configuration created."
    fi

    # Create static IP config
    cat <<EOF > /etc/sysconfig/network-scripts/ifcfg-$INTERFACE
DEVICE=$INTERFACE
NAME=$INTERFACE
BOOTPROTO=none
ONBOOT=yes
IPADDR=$IPV4
NETMASK=$SUBNET_MASK
GATEWAY=$GATEWAY
DNS1=$DNS1
DNS2=$DNS2
HWADDR=$MACADDR
EOF

    # Restart network
    nmcli connection reload
    nmcli connection down $INTERFACE && nmcli connection up $INTERFACE

    echo "Network and DNS configuration applied permanently on RHEL-based system."

else
    echo "Unsupported package manager. This script supports only apt (Debian-based) or dnf (RHEL-based) systems."
    exit 1
fi