Blog

Linux - Advanced Network Configuration

Linux, as a highly flexible operating system, offers extensive network configuration capabilities. This allows you to build complex and efficient infrastructures tailored to various needs. In this guide, we will cover three key aspects of advanced network configuration: VLANs, bridging, and routing, providing detailed steps and practical examples.

VLANs (Virtual LAN): Network Segmentation

VLANs enable the division of a single physical network into logical segments, enhancing security, improving performance, and simplifying network management.

How to configure VLANs?

Install necessary tools: Ensure that the iproute2 tools are installed.
Create a VLAN interface:
```
sudo ip link add link eth0 name eth0.10 type vlan id 10
```
- eth0: Physical interface.
- eth0.10: VLAN interface name.

Assign an IP address:

sudo ip addr add 192.168.10.1/24 dev eth0.10

Activate the VLAN interface:
```
sudo ip link set eth0.10 up
```
Configure trunking: For Cisco switches, use commands like:
```
switchport mode trunk
switchport trunk allowed vlan
```

Bridging: Connecting Networks

Bridging allows connecting different interfaces into a single logical network, which is particularly useful in virtualization or creating access points.

How to configure a network bridge?

Install the tool:
```
sudo apt-get install bridge-utils
```
Create a bridge:
```
sudo brctl addbr br0
```

Add interfaces to the bridge:

sudo brctl addif br0 eth0
sudo brctl addif br0 wlan0

Assign an IP address to the bridge:
```
sudo ip addr add 192.168.1.1/24 dev br0
```

Activate the bridge and interfaces:

sudo ip link set br0 up
sudo ip link set eth0 up
sudo ip link set wlan0 up

Routing: Managing Network Traffic

Routing enables the transmission of data between different networks – a key component in more complex infrastructures.

Static routing:

Add a static route:

sudo ip route add 10.0.0.0/24 via 192.168.1.254

Add a default route:

sudo ip route add default via 192.168.1.254

Dynamic routing:

For dynamic routing, use tools like Quagga or FRRouting. For example, an OSPF configuration:

router ospf
 network 192.168.1.0/24 area 0

Monitoring and Diagnostic Tools

iproute2: Comprehensive network configuration.
tcpdump: Network traffic analysis.
iftop: Monitoring interface bandwidth usage.
mtr: Diagnostics (traceroute and ping).

Advanced network configuration in Linux requires an understanding of VLANs, bridging and routing. With these techniques, you can create complex, secure and efficient networks. Remember to monitor and test your configuration regularly to ensure network stability and reliability.