When running a web server inside VirtualBox (specifically on an Ubuntu guest with Windows Vista host), you'll need proper network configuration. The default NAT mode won't allow host access to guest services.

# Check current network interface configuration in Ubuntu guest
ifconfig -a

The most reliable method is using Bridged Adapter mode:

1. Power off your Ubuntu VM
2. Open VirtualBox settings
3. Navigate to Network → Adapter 1
4. Change "Attached to" to "Bridged Adapter"
5. Select your host's network interface

If bridged mode isn't possible, configure port forwarding:

VBoxManage modifyvm "VM name" --natpf1 "webserver,tcp,,3000,,3000"

This forwards host's port 3000 to guest's port 3000.

Ensure Ubuntu's firewall allows the connection:

sudo ufw allow 3000/tcp

After configuration, from your Windows host:

# Using PowerShell to test connection
Test-NetConnection -ComputerName [GUEST_IP] -Port 3000

Then access via browser using either:

• http://[GUEST_IP]:3000 (bridged mode)
• http://localhost:3000 (NAT with port forwarding)

If connections fail:

1. Verify the web server is running: sudo netstat -tulnp | grep 3000
2. Check guest IP: ip a
3. Test connectivity between host/guest: ping [GUEST_IP]

When running a web server inside a VirtualBox Ubuntu guest on a Windows host, the default 127.0.0.1 (localhost) binding only works within the guest OS. To make it accessible from the host machine, we need to configure proper network settings in VirtualBox.

First, ensure your VM is using either Bridged or NAT networking with port forwarding:

1. Shut down your Ubuntu VM
2. Open VirtualBox Manager
3. Right-click your VM → Settings → Network
4. Set "Attached to" to either:
   • Bridged Adapter (recommended for development)
   • NAT (with port forwarding)

With bridged networking, your VM gets its own IP on your local network:

# In Ubuntu guest, find the IP address:
ifconfig | grep "inet "

# Sample output might show something like:
inet 192.168.1.15 netmask 255.255.255.0

Now you can access the web server from your Windows host at http://192.168.1.15:3000

If bridged networking isn't suitable, configure port forwarding:

# With the VM powered off:
VBoxManage modifyvm "VM name" --natpf1 "webserver,tcp,,3000,,3000"

# Breakdown of the command:
# "webserver" - Rule name
# tcp - Protocol
# 3000 - Host port
# 3000 - Guest port

Now access the server at http://localhost:3000 from your Windows host.

Ensure your web server is binding to all network interfaces (0.0.0.0) rather than just localhost. For example in Node.js:

const http = require('http');
const server = http.createServer((req, res) => {
    res.end('Hello from VirtualBox!');
});

// Bind to all network interfaces
server.listen(3000, '0.0.0.0', () => {
    console.log('Server running at http://0.0.0.0:3000/');
});

• Firewall blocking: Check Ubuntu's ufw and Windows Defender settings
• Port conflicts: Verify no other service is using port 3000
• Binding issues: Server must listen on 0.0.0.0, not 127.0.0.1