How can I list all IPs in the connected network, through Terminal preferably?

This Anwswer determines the subnet by itself while in the other anwsers you need to provide it.

The script uses arp -a or ip -o -f inet addr show to find the subnet.

I've build the script elaborating on @anders-larsson and @mathieu-caroff 's anwsers. I avoid the use of 'nmap', but the script is easil amended to use nmap.

Basically, $baseip is built using bash replacement macros in the second part of the script if no parameter is provided on the command line. Otherwise it will scan the provided subnet (style: 192.1.5 without the third dot last byte of the IP).

#!/bin/bash
function scan ()
{
    for ip in $1.{1..254}; do
        ping -c 1 -W 1 $ip &
    done | sed -nE 's:^.* from ([0-9.]+).*time=(.*s)$:1 (2):p'
    wait
}

if [ $1 ]; then
    for baseip; do
        scan $baseip
    done
else
    baseip=$(arp -a) && baseip=${baseip%%)*} && baseip=${baseip##*(}
    if [ $baseip"" == "" ] ; then
      baseip=$(ip -o -f inet addr show|grep "scope global") && baseip=${baseip##* inet} && baseip=${baseip%%/*}
    fi
    baseip=${baseip%.*}
    scan $baseip 
fi

Ellaborating on Anders Larrson's answer -

#!/bin/bash
function scan ()
{
    for ip in $1.{1..254}; do
        ping -c 1 -W 1 $ip &
    done | sed -nE 's:^.* from ([0-9.]+).*time=(.*s)$:1 (2):p'
}

if [ $1 ]; then
    for baseip; do
        scan $baseip
    done
else
    scan 192.168.1
fi

Came up with the following on a nexus using tmux as arp-scan isn't in the repo but nmap came pre-installed, displays just the ip addresses:

nmap -sn 192.168.1.1-254/24 | egrep "scan report" | awk '{print $5}'

For a more compact list of connected devices:

nmap -sL 192.168.0.* | grep (1

Explanation.

nmap -sL 192.168.0.* will list all IPs in subnetwork and mark those, that have name:

Nmap scan report for 192.168.0.0
Nmap scan report for Dlink-Router.Dlink (192.168.0.1)
Nmap scan report for 192.168.0.2
...
Nmap scan report for android-473e80f183648322.Dlink (192.168.0.53)
...
Nmap scan report for 192.168.0.255

As all interesting records start with parenthesis ( and digit 1, we filter for that with | grep (1 (backslash is needed to escape parenthesis)

Quirk
Beware that if two devices have the same name, nmap will show only the one, that was connected to router last

Try installing nmap (sudo apt-get install nmap) and type nmap 192.168.1.0/24 substituting 192.168.1 with the first three parts of your ip address (find out using ip addr).

You can also get a slightly less accurate (in my experience) map of a network by running ping 192.168.1.255 (again substituting 192.168.1), which should issue a ping to every machine on the network, but, in my experience, does not always function correctly.

If your network is 192.168.0.0/24, make an executable file with the following code; Change the 192.168.0 to your actual network.

#!/bin/bash
for ip in 192.168.0.{1..254}; do
  ping -c 1 -W 1 $ip | grep "64 bytes" &
done

Use nmap. example: nmap -sn 10.10.10.0/24 The arp cache will only tell you those that you have tried to contact recently.

Check out the arp-scan command - you will probably have to install it eg:

sudo apt-get install arp-scan

http://manpages.ubuntu.com/manpages/hardy/man1/arp-scan.1.html

And to give further detail:

sudo arp-scan --interface=eth0 --localnet

Where eth0 is your device. You can find your device with:

ifconfig

In windows this would be arp -a an equivalent of that in Linux would be arp -e.

From the man page for arp:

arp with no mode specifier will print the current content of the table.
-e : Use default Linux style output format (with fixed columns).