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how to get a list of the connected wifi clients in OpenWrt 10.03?

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5 Answers 5

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16

You may use the arp-table, or DHCP-leases. Not a perfect solution, maybe it's enough?

List arp-table

arp

List DHCP-leases

cat /tmp/dhcp.leases

... and combined

for ip in $(arp | grep -v IP | awk '{print $1}'); do 
    grep $ip /tmp/dhcp.leases; 
done
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4
  • 3
    You have recent leases too, like a powered off laptop and a phone currently on another wifi network.
    – Dereckson
    Aug 4, 2014 at 17:54
  • 1
    I still have empty response cat /tmp/dhcp.leases, while many devices got IP and network settings from WIFI of OpenWRT.
    – Boris Ivanov
    Aug 19, 2017 at 18:25
  • This will not work if your router works as a bridge, since it doesn't offer the DHCP itself.
    – Raúl Salinas-Monteagudo
    Nov 28, 2018 at 9:49
  • 1
    This doesn't list wifi clients. The info it finds is sometimes related, but it doesn't really answer the question.
    – Stefan
    Oct 24, 2022 at 14:33
20

In order to see associated wifi clients, even if they don't have a DHCP Client or have no ip, you have to ask the AP for associated wifi devices:

# MAC80211
iw dev wlan0 station dump

# Universal (Tested with OpenWRT 14.07 and 15.05.X)
# iwinfo must be installed first as it is optional
# opkg update && opkg install iwinfo
iwinfo wlan0/wl0/ath0 assoclist

# using hostapd
ubus call hostapd.wlan0 get_clients

# Proprietary Broadcom (wl)
wl -i wl0 assoclist
 
# Proprietary Atheros (madwifi)
wlanconfig ath0 list sta

This way you will also see the connection speed. For me this is looking like this:

# iwinfo wlan0 assoclist
12:34:56:78:9A:BC  -26 dBm / -95 dBm (SNR 69)  1930 ms ago
RX: 24.0 MBit/s, MCS 0, 20MHz                   3359 Pkts.
TX: 130.0 MBit/s, MCS 14, 20MHz, short GI       1209 Pkts.
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3

Instead of cat /tmp/dhcp.leases|wc -l and arp -a, my solution is 

opkg update
opkg install arp-scan
arp-scan --interface=br-lan --localnet | grep responded | awk '{print $12}'

It will return the number of devices which connected to OpenWRT by LAN port. Almost real time.

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2

How about nmap?

opkg install nmap

Then do a stealth scan of your subnet (likely 192.168.1.0/24)

nmap -sS 192.168.1.0/24

This will list services running on the clients as well. It may also set off alarms if the client has port-scan detecting software (i.e snort) installed so be careful.

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  • You generate traffic here. If you just want to keep statistics every minute, for example you would be creating traffing, radiation and consumption needlessly. I am thinking about the case where you want to know if your mobile phone is at your place, for a house automation system. You don't want to drain your phone battery for this.
    – Raúl Salinas-Monteagudo
    Nov 28, 2018 at 9:58
2

To get them directly from hostapd (the daemon that manages the access point):

$ ubus call hostapd.wlan0 get_clients

{
    "freq": 2462,
    "clients": {
        "<mac addr 1>": {
            "auth": true,
            "assoc": true,
            "authorized": true,
            "preauth": false,
            "wds": false,
            "wmm": true,
            "ht": true,
            "vht": false,
            "wps": false,
            "mfp": false,
            "rrm": [
                0,
                0,
                0,
                0,
                0
            ],
            "aid": 1
        }
    }
}

(or replace wlan0 with the interface you are interested in)

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