how to find other machines which are connected same network

Question

I tried to find all machines which are connected my modem. I tried 192.168.x.0/24 command on gnome-terminal but it couldn't find any. My brother's laptop and my mobile phone are already connected the modem but this command couldn't find them.

Here is the output :

root@tugrul:/home/tugrul# nmap -sP 192.168.1.0/24
Starting Nmap 6.40 ( http://nmap.org ) at 2015-09-22 01:40 EEST
Nmap scan report for 192.168.1.1
Host is up (0.0050s latency).
MAC Address: xx:xx:xx:xx:xx:xx (Shenzhen Zowee Technology Co.)
Nmap scan report for 192.168.x.x
Host is up.
Nmap done: 256 IP addresses (2 hosts up) scanned in 3.40 seconds

I also tried nmap -sn 192.168.6.0/24 but there was no difference:

$ nmap -sn 192.168.6.0/24
Nmap scan report for 192.168.1.1
Host is up (0.0043s latency).
MAC Address:  (Shenzhen Zowee Technology Co.)
Nmap scan report for 192.168.1.15
Host is up.
Nmap done: 256 IP addresses (2 hosts up) scanned in 3.06 seconds

How can I do that ?

Please don't use version tags (e.g. 14.04) unless your issue is only relevant to one version of Ubuntu. — terdon, Sep 21 '15 at 22:54
That's strange. The command you show should have worked. Are you sure the other devices are on the same network? Is their IP address 192.168.1.XX? — terdon, Sep 21 '15 at 22:55
Yes, the other devices are connected same modem in my room. But command couldn't find. I'm triying last 2 ours. — m.tuğrul, Sep 21 '15 at 22:57
Use sudo before the nmap command as TCP SYN packets are sent to only ports 80 and 443 when nmap -sP is run as unprivileged user.. — heemayl, Sep 21 '15 at 23:00
I wanna ask one thing, when I start working on terminal, I do sudo su and I work as root. I'm new on Linux. Is not it same? — m.tuğrul, Sep 21 '15 at 23:02
@heemayl ah, yes, I missed that. Still strange though, nmap -sP 192.168.1.0/24 shows all machines on my network. m.tuğrul could you show us the IPs of the machines you can't find? Don't worry, sharing internal IPs (e.g. 192.168.1.10) is completely safe. — terdon, Sep 21 '15 at 23:11
yes I am already working as a root. I wrote sudo su and I started to work as root — m.tuğrul, Sep 21 '15 at 23:13
I addition to what @terdon has asked for could you please run it as nmap -sn 192.168.6.0/24 as root of course..just want to check as -sP is deprecated in favor of -sn.. — heemayl, Sep 21 '15 at 23:14
@m.tuğrul no, just copy the text from the terminal and paste it into your answer. I still suspect that these machines are not on the same network somehow, so please also show i) your internal IP and ii) the internal IP of one of the devices. — terdon, Sep 21 '15 at 23:16
I already paste output of process as an ansver and I checked devices. Devices is already connected my modem. — m.tuğrul, Sep 21 '15 at 23:30
Thanks (I added it to your question instead) but you still haven't told us the IP you are trying to find. As I said, there is no danger in sharing internal IPs (they are only accessible from inside your network) and it would help us be sure that you're running the right command. — terdon, Sep 21 '15 at 23:33
192.168.1.2 my brothers machine ip. I know I know but I forgot sharing the ip which I want to find. — m.tuğrul, Sep 21 '15 at 23:38
Add the output of ifconfig for both systems, also, what OS your brother use? — Braiam, Sep 22 '15 at 15:54
my brother use Windows 7, I'm out of city for 5 days. I didn't bring my computer with me, it stayed at home. — m.tuğrul, Sep 22 '15 at 16:14
Doesn't work doesn't work I'll be crazy doesn't work. Now 5 machines are connected my modem but I can't find ip address of them on my ubuntu.Please help me. — m.tuğrul, Sep 27 '15 at 19:13
hi guys, I found ip adresses on my local network. I wan't ask you one more things. How to connect to other machine via network ports? Is that possible? I know software development (Java). — m.tuğrul, Oct 03 '15 at 10:44

score 2 · Answer 1 · answered Sep 21 '15 at 22:53

2

try arp-scan. install it by sudo apt install arp-scan:

sudo arp-scan -l

answered Sep 21 '15 at 22:53

Doesn't exists other way? I'll try your solution but Can't we do that without tools? – m.tuğrul Sep 21 '15 at 22:55
you'll probably need to run something. I'm not sure what you mean with "tools" though. – Sep 21 '15 at 22:58
Is arp-scan a tool like nmap developed by some guy or I understand wrong this? – m.tuğrul Sep 21 '15 at 23:00
every piece of software is developed by "some guy" afaik. – Sep 21 '15 at 23:07
thank you for your interest, I tried but it doesn't find other devices. I checked the other devices, they are connected but I couldn't find with arp-scan or my way. Thank you again – m.tuğrul Sep 21 '15 at 23:10

Root · Answer 2 · 2015-09-22T16:20:33.250

2

Use netdiscover

netdiscover -i <interface>

If you're trying to find the devices in the wifi network, the command would be

netdiscover -i wlan0

edited Sep 22 '15 at 16:20

answered Sep 22 '15 at 16:02

Root

106

Is interface a parameter or value? Should I run same form yours? – m.tuğrul Sep 22 '15 at 16:19
There was an extra space before that 'i', sorry about that. I removed it. – Root Sep 22 '15 at 16:21
Doesn't matter, thank u so much, I'll try when I arrive to home – m.tuğrul Sep 26 '15 at 22:11

score 0 · Answer 3 · edited May 23 '19 at 06:08

0

Your command should have worked. It does on my system anyway, as does arp-scan as suggested by Adonis. If, however, you don't want to install any tools, you could use a brute approach and just ping everything:

for i in 192.168.1.{1..100}; do 
    ping -w 1 -c 1 $i >/dev/null && echo "$i is up"; 
done

The command above will ping every IP between 192.168.1.1 and 192.168.1.100. If a host is pingable (if it is connected), it will print the host's name.

However, this will be slow and cumbersome and is not really a good solution. Use arp-scan or nmap as you did instead.

edited May 23 '19 at 06:08

Pang

373

answered Sep 21 '15 at 23:03

terdon

104,404

Thank you for your interest, all of you. Why isn't my command working on my network but working on yours? It made me crazy. – m.tuğrul Sep 21 '15 at 23:04

how to find other machines which are connected same network

3 Answers3

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