Score:0

Ubuntu

Get up address of all devices connected to a Netgear switch

Zillur Rahman

6/17/24, 2:12 AM

I have a Netgear switch that has 8 Ethernet ports. I connected 4 devices to that switch and then I connected the switch to my Ubuntu 22.04 PC using Ethernet cables. Now, I see only the IP address of the switch in my network. How can I get separate IP address of all 4 devices?

I don't know much about computer networks. So, couldn't figure it out myself.

Edit: switch model: Netgear Prosafe GS108E. Not sure how it was setup. What I am doing now: just connected devices with it and it to the PC. Automatic DHCP fails, so using local link.

Ip address of the switch: 169.254.244.240

zillur@trc:~$ sudo nmap -sn 169.254.244.240
Starting Nmap 7.80 ( https://nmap.org ) at 2023-06-17 11:59 PDT
Nmap scan report for trc (169.254.244.240)
Host is up.
Nmap done: 1 IP address (1 host up) scanned in 0.00 seconds

arp -a

os-992315000023.local (169.254.118.247) at bc:0f:a7:00:94:c3 [ether] on enp4s0
my.mifi (192.168.1.1) at 28:80:a2:e2:0d:62 [ether] on enx0015ff318831

1 + 7

network-manager

ip-address

ethernet

22.04

waltinator

6/17/24, 2:27 AM

You probably can't. The Switch is performing NAT (Network Address Translation), which conceals client IP addresses. You could use `ping` (`man ping`) to ping the broadcast address (host portion of IP address is all 1s or all 0s) and see if the nodes answer. Read `man ip ip-route` to be sure you route your packets for the client address range to the NetGear.

Thomas Ward

6/17/24, 2:32 AM

@waltinator Most switches are *not* NAT capable switches. MOST switches off the shelf are "dumb switches" and part of the same VLAN, so you could theoretically scan for all devices on the IP range you're connected to as well. *Managed* switches will have NAT or VLAN separation, but the average off-the-shelf switch that MOST people have are not managed switches (managed switches are more business/enterprise grade equipment). And dumb desktop / pocket switches aren't capable of client restrictions per port.

Thomas Ward

6/17/24, 2:34 AM

What type of switch are you using? What's the manufacturer and model? How is it set up or configured?

oldfred

6/17/24, 2:46 AM

What does nmap show? Find your ip4 address and something like this`sudo nmap -sn 192.168.1.0/24` or `sudo nmap -sP 10.0.0.0/24` If you input incorrect range, it just sits there forever.

Zillur Rahman

6/17/24, 7:07 PM

I edit the post

Thomas Ward

6/17/24, 7:30 PM

Without knowing how the switch is configured, it's impossible to really answer. You could be on a different VLAN, port isolation could be turned on (that's possible with that switch model you said), and the 169.254 address is a private link-only address assigned by your computer NOT the network, so you won't likely be able to scan everything on the network and find the IP of other devices. And without DHCP working that means you're on a non-functioning network segment. Is this your own switch or something like a switch at the workplace?

oldfred

6/17/24, 9:38 PM

You are putting in a single device's address, you have to use a range as in example in answer or comment above.

Score:0

Ubuntu

mpboden

6/17/24, 2:50 AM

You have a few options:

If your devices are setup via DHCP, then you should be able to log into your router and see what IP addresses were leased.

On the command line:

arp -a
sudo arp-scan 192.168.1.0/24. Simply substitute your own subnet.
sudo nmap -sn 192.168.1.0/24. Likewise, substitute your own subnet.

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EN: Get up address of all devices connected to a Netgear switch

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