Temporary Network Configuration Guideline (Linux)

This guideline describes how to set up a temporary network configuration on a Linux server using ip commands. These changes will only persist until the next reboot.

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1. Identify Your Network Interface

Check available network interfaces and note the one you want to configure (e.g., ens3).

ip link show

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2. Flush Existing IP Addresses

Remove all current IP addresses from your interface to avoid conflicts.

sudo ip addr flush dev ens3

Replace ens3 with your actual interface name.

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3. Assign a New IP Address

Set the desired IP address and subnet mask.

sudo ip addr add 51.1.1.51/24 dev ens3

• 51.1.1.51 is the new IP.

• /24 is the subnet mask (255.255.255.0).

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4. Bring the Interface Up

Activate the interface if it is down.

sudo ip link set ens3 up

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5. Set Up Routing

a. Add a Static Route (Optional)

If you need to reach a specific host directly:

sudo ip route add 15.2.2.15 dev ens3

b. Set the Default Gateway

Direct all traffic through the gateway:

sudo ip route add default via 15.2.2.15

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6. Configure DNS

Set a DNS server to resolve domain names.

echo "nameserver 8.8.8.8" | sudo tee /etc/resolv.conf

This replaces your /etc/resolv.conf with Google’s DNS.
Note: Changes to /etc/resolv.conf are also temporary and may be overwritten by network managers.

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7. Automatic Setup Script

You can use the following shell script to automate this temporary network setup.
This script will prompt you for the required details and apply the configuration.

#!/bin/bash

# Temporary Linux Network Configuration (Interactive Script)

echo "=== Temporary Network Configuration ==="

# Prompt for network interface
read -p "Enter the network interface name (e.g., ens3): " IFACE

# Prompt for new IP address (with CIDR)
read -p "Enter the new IP address with CIDR (e.g., 192.168.1.100/24): " IPADDR

# Prompt for Gateway
read -p "Enter the gateway IP address (e.g., 192.168.1.1): " GATEWAY

# Prompt for DNS
read -p "Enter the DNS server IP (e.g., 8.8.8.8): " DNS

echo ""
echo "Applying network changes..."

# Flush existing IP addresses
sudo ip addr flush dev "$IFACE"

# Assign new IP address
sudo ip addr add "$IPADDR" dev "$IFACE"

# Bring the interface up
sudo ip link set "$IFACE" up

# Add default gateway
sudo ip route add default via "$GATEWAY"

# Set DNS server
echo "nameserver $DNS" | sudo tee /etc/resolv.conf

echo ""
echo "Network configuration applied (temporarily, until reboot)."
echo "Current network status:"
ip addr show "$IFACE"
ip route

echo ""
echo "Test connectivity (ping DNS server):"
ping -c 4 "$DNS"

echo ""
echo "Done."

Usage:

1. Save as network_setup_prompt.sh.

2. Make executable: chmod +x network_setup_prompt.sh

3. Run: ./network_setup_prompt.sh

4. Follow prompts to input interface, IP address, gateway, and DNS.

Note:
This configuration is temporary and will be lost after a reboot. For permanent changes, edit your network configuration files.

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8. Verify Configuration

a. Check IP Address

ip a

b. Check Routing Table

ip route

c. Test Connectivity

• Ping gateway or external IP:

    ping -c 4 8.8.8.8
  

• Test DNS:

    ping -c 4 google.com
  

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9. (Optional) Install Open vSwitch

If you need Open vSwitch for virtual networking:

sudo apt update
sudo apt install openvswitch-switch

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10. Notes

• Temporary: These changes will be lost after a reboot. For permanent changes, edit your network configuration files (e.g., /etc/network/interfaces, Netplan, or NetworkManager settings).

• Permissions: All commands require root privileges (sudo).

• Interface Name: Replace ens3 with your actual interface name.

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11. Troubleshooting

• If network is not working, check:

  • IP address assignment: ip a

  • Routing table: ip route

  • DNS settings: cat /etc/resolv.conf

  • Interface status: ip link show ens3

• Re-run commands if you made a mistake or want to reset.