Today I logged in a machine I don’t want to install anything on it, but I wanted to find a machine in its network.
I came up with the little shell script that scans the subnet:
CURR=1
SUBNET="192.168.0"
while [ $CURR -lt 255 ] ; do
ping -c1 -t1 $SUBNET.$CURR 2>&1 >/dev/null
if [ "$?" -eq "0" ]; then
echo "$SUBNET.$CURR"
fi
let CURR=$CURR+1
done
This script is suboptimal but it does the stuff: It uses ping with a timeout of 1 sec, so If no machine is up, the script takes around 255 seconds to scan the subnet, it doesn’t list the machines that doesn’t reply to ping and so on … but as I said it , it does the stuff.
I tested this script in Linux and OSX.
A random weblog but it's mine 
FreedomSound said
About 4min to scan subnet.. Waow.. Great Job 😉
Is -W option to speed up your script ?
smaftoul said
I think 4 minutes is slow ! 🙂
‘-W’ is the timeout, I set the timeout to 1 sec , this is the minimum you can set !
Billigflug said
Looks like a nice one, I’ll give it a try tomorrow. I have to see and log and maybe then I can give you some suggestions to boost its speed a little.
smaftoul said
Hi Billigflug !
I would be very happy if you make some suggestions !
I would also be happy if it works for you, and don’t forget to tell me the os on which it works (or doesn’t) ! 🙂
federico cattozzi said
I have edit the script and now it’s very fast!
It uses parallel jobs to execute many pings at the same time.
#!/bin/bash
CURR=1
SUBNET=”$1″
FILE=multiping.log
touch $FILE
function multiping() {
ping -c1 -t1 $SUBNET.$CURR 2>&1 >/dev/null
if [ “$?” -eq “0” ]; then
echo $(arp $SUBNET.$CURR) >> $FILE
fi
}
while [ $CURR -lt 255 ] ; do
multiping &
let CURR=$CURR+1
let MOD=$CURR%100
#this code is for prevent the saturation of the executable connections
if [[ $MOD -eq 0 ]]; then
wait
fi
done
wait
cat $FILE
rm $FILE
federico cattozzi said
Excuse me, i have forgotten the use:
MacChicken:~ federico$ bash multiping.sh 192.168.1
The only parameter is the subnet ip: 192.168.1 for example.
I tested this script in Debian and MacOSX.
Enjoy!
Philipe said
I have tried pasting both of these into Apple’s Script Editor but they don’t appear to work. What am I missing?
smaftoul said
Philipe: it’s not applescript, it’s shell script.
To use it, create a file with the script, launch a terminal, do chmod +x /path/to/filename_of_script and the execut: /path/to/filaname 192.168.0 for example. Hope this helps !
thewrz said
Did exactly what I needed. Thanks dude.
eric said
I think “ping -b ” can solve the problem easily.
ping -b 192.168.18.255
WARNING: pinging broadcast address
PING 192.168.18.255 (192.168.18.255) 56(84) bytes of data.
64 bytes from 192.168.18.108: icmp_seq=1 ttl=64 time=0.104 ms
64 bytes from 192.168.18.105: icmp_seq=1 ttl=64 time=0.203 ms (DUP!)
smaftoul said
Not every platform answers to a broadcast ping, but that may be a good start !
john said
um… has no one heard of nmap? It does exactly this and soooo much more.
nmap -sP 192.168.1.0/24
try it, if you don’t have it installed, shame on you!
;^)
Gary said
Cool script for an impatient Linux newb. We’re on Centos and added -w1 and it helped performance significantly.
thx!