Tag Archive for: network

Find Out Who’s on Your Network with One Simple Command

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Want to see all devices connected to your local network? Try this quick Linux command:

sudo arp-scan --interface=eno2 -l

What does it do?

  • sudo: Runs with superuser privileges (required for network access).
  • arp-scan: Scans for devices using the ARP protocol.
  • --interface=eno2: Specifies the network interface (like your Ethernet or Wi-Fi).
  • -l: Scans the entire local network (same as --localnet).

What will you see?

  • Each device’s IP address
  • MAC address
  • Device vendor (if recognized)

Great for:

  • Checking who’s connected to your Wi-Fi
  • Spotting unknown or suspicious devices
  • Managing your local network

Connecting to a ModBerry 500 via SSH with Dual Ethernet outside the local network

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Context

Industrial devices like the ModBerry 500 often come with multiple Ethernet interfaces — typically with eth0 set to a static IP (e.g., 192.168.0.101) and eth1 (e.g., 192.168.20.118) configured via DHCP on your local network.


In some cases, you’ll want to ensure that a specific interface — for example, eth1 — is used as the primary route for Internet access. This is especially important if you plan to remotely connect to the device via SSH, using a custom external port (like 2223) forwarded through your router.

The Problem

Even if you configure the IP and gateway on eth1, Linux may still use eth0 as the default route, because it automatically assigns routing priorities (metrics). In our case, eth1 ended up with metric 203 and eth0 with 202 — making eth0 the preferred route. That’s the opposite of what we wanted.

The Solution: Prioritize eth1 via /etc/dhcpcd.conf

If your system is using dhcpcd as its network manager (which is common on ModBerry), you can set the interface priority easily.

1. Open the config file:

sudo nano /etc/dhcpcd.conf

2. Add this at the end:

interface eth1
  metric 100

interface eth0
  metric 200

This tells the system: “Use eth1 first, because it has a lower metric.”

3. Restart the service:

sudo systemctl restart dhcpcd

4. Check the active routes:

ip route show

You should see something like:

default via 192.168.120.1 dev eth1 metric 100
default via 192.168.0.99 dev eth0 metric 200

Open SSH Access on Port 2223 via Router NAT (e.g., pfSense)

In this setup, we’re accessing the ModBerry remotely by forwarding a custom external port (like 2223) on the router’s public IP to port 22 on the ModBerry’s eth1 IP address.

1. Set up a NAT Port Forwarding rule on your router (e.g., pfSense)

  • External port: 2223
  • Internal IP: your ModBerry’s eth1 IP (e.g., 192.168.120.118)
  • Internal port: 22 (default SSH port)
  • Protocol: TCP

This tells your router: “When someone connects to port 2223 on the public IP, forward that to port 22 on the ModBerry’s eth1 interface.”

2. From outside your network, connect using:

ssh -p 2223 user@YOUR_PUBLIC_ROUTER_IP

Replace user with your actual ModBerry username (e.g., root or pi), and YOUR_PUBLIC_ROUTER_IP with the WAN IP of your pfSense router.

Detect your IO-Link masters

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If your IO-Link masters are connected to your network, you can use arp-scan command-line tool to discover and fingerprint ARP (Address Resolution Protocol) hosts.

sudo arp-scan -l

Smart City installations

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Here you are, our Smart Radio Network installations in Spain. Any of these mesh networks works in the Free Band frequency, so you don’t have to pay for comunications. The maximum scope between two isolated nodes is up to 1 km. This is our own technology:

There are also others technologies, such as WiFi, Zigbee, etc; but they don’t have enough scope or they are more expensive in practice. Some competitors like Philip are using 3G/4G but that makes you pay each month per each node and they cannot control as many nodes as we do, we have networks with up to 3000 nodes and growing up. Some of our current customer came from competitors solutions.

In Helios, our lighting system, we are using our network to control each light individually, groups and monitoring consumption. We solve the energy deficiencies and cost of lighting in cities, we reduce human resources of lighting maintenance and detect lighting problems. Citizen wanted better quality services, they used to be the ones who notify lighting problems. With Helios one person can manage many installations at the same time. Full remote control of your lighting and consumption.

I’m really proud of what we have created because we reduce contamination, energy and costs. These things are possible when you work with a great team full of good values with a common goal: a better world.

🙂

Currently, we are doing research to modify our radio transmission network into a network for the Internet of Things. A network full of sensors: presence, movements, contamination, temperature, noise detections, etc. Once we have installed our new firmware, it will be so easy to add sensors. The lights have created the city network for that.

  • With presence detectors (commercial devices) in our network, we can light up those bus stop where there are people standing, crosswalks and so on.
  • Using modules in trash tracks we can light up the street where the workers are, and change the illumination in real time at the same time they are moving, while they are driving to the next container.
  • We will be able to detect contamination per zones or even on streets.
  • We will be able to stop extra irrigation of green zones detecting humidity.
  • We will be able to control traffic lights.