Why can't I find the local IP of my PI?

Question

I tried the following command to find the local IP of my RPI:

nmap -sP 192.168.1.1-254

But, the only IP I find is my PC. I know that my PI is at 192.168.1.6 which I can SSH into without any problem and I can even ping it. What can I do to get the local IP of my PI from my terminal on my PC?

Answer 1

Here's a script that will find all¹ of the Raspberry Pi's on your local network:

#!/bin/sh

: ${1?"Usage: $0 ip subnet to scan. eg '192.168.1.'"}

subnet=$1
for addr in `seq 0 1 255 `; do
( ping -c 3 -t 5 $subnet$addr > /dev/null ) &
done
arp -a | grep -E --ignore-case 'b8:27:eb|dc:a6:32'

• Copy & paste this into your text editor on RPi (nano), then save/write it as pingpong.sh in your home directory

• make it executable:

chmod 755 pingpong.sh

• execute it (use your network address here, not necessarily 192.168.1.):

./pingpong.sh 192.168.1.

Your output may look like this: This output reflects my network; it has 2 RPis connected, and one of them is a 3B+ with WiFi enabled and the other an oldie 1bp connected via Ethernet:

raspberrypi3b.local (192.168.1.144) at b8:27:eb:12:34:56 on en0 ifscope 
raspberrypi1bp.local (192.168.1.179) at b8:27:eb:78:9a:bc on en0 ifscope 

---

Notes:
1. All Pi's that have a MAC address whose first 24 bits are one of the two OUI numbers assigned to the Raspberry Pi Foundation. This may not include Pi's using 3rd party network hardware, or those whose MAC address has been 'spoofed'.

Answer 2

Add this to your .bash_aliases to get your ipv4, modify as needed to get the 6.

function ipv4() { ifconfig wlan0 | grep "inet " | awk '{ print $2 }' ; }

I'm running raspian as of this current date. -Steve

oops... edit: change wlan0 to your current device.

Another Edit: this can sometimes help:

function displ() { printf "`who | tail -1 | sed 's/[()]//g' | awk '{print $5}'`:0.0" ; }

Answer 3

I modified Seamus script to automatically determine subnet and to work on macOS or Linux.

#! /bin/sh
# find Raspberry Pi IP Address on macOS or Linux
# https://raspberrypi.stackexchange.com/a/122395/8697
# 2021-05-11

# Check if ip commend exists i.e. Linux
IPEXISTS=$(which ip)
ret=$?

if [ $ret -eq 0 ] ; then
    ISLINUX='Y'
fi

if [ $ISLINUX ]; then
    GATEWAY=$(ip route | grep default | head -n1 | awk '{print $3}')
else
    GATEWAY=$(route get default | grep gateway | awk '{print $2}')
fi

SUBNET=$(echo $GATEWAY | awk -F '.' '{print $1"."$2"."$3"."}')

for ADDR in `seq 0 1 255 `; do
( ping -c 1 -t 5 $SUBNET$ADDR > /dev/null 2>&1 ) &
done

arp -a | grep -E --ignore-case 'b8:27:eb|dc:a6:32'