Posted: Mon Jul 18, 2022 18:44 Post subject: [SOLVED] "Active Clients" vs "arp"
Elsewhere in the forums, I read that the GUI "Active Client" list (under "Status->Lan") is generated by 'arp'
However, the "Active Client" list in the gui is significantly longer than the list generated by "arp -a".
The GUI also sometimes has multiple IP addresses for the same device/MAC -- possibly because it is caching old/stale connections.
Also, the number of arp connections tends to change minute to minute (without any devices being intentionally connected/disconnected) -- e.g., on my network it can go from 27 to 21 in a matter of seconds.
On the other hand, the GUI list is relatively stable.
So is there some caching going on in the GUI?
What Linux command/script is run to generate the GUI list?
Thanks
Note: I have a Netgear r6700 running DD-WRT v3.0-r47206 std (08/19/21)
It's always been my understanding that any "active client list", whatever the firmware, comes from a variety of sources, be it arp, the wireless adapter(s), DHCP leases, etc. There is no single source for that list because the very idea of an "active client list" is a false notion when it comes to IP.
The IP network is NOT like the old POTS telephone system, where each phone has an hardwired electrical connection to the central telephone switching station. It's packet-switched, and is therefore more stateless in its behavior. You only KNOW a client is active if in fact you "see" packets. But if that device is just idling at any given time, is it or is it NOT actively connected? It's ambiguous due to the nature of how IP works.
That's why all such active client lists are problematic. Most are just a mishmash of various sources that *attempt* to provide something we humans would consider "connected". But if you're depending on something like arp, beware that will eventually be dropped if the client goes silent. But that doesn't mean it's NOT actively connected. NOT if you consider still being pingable (which requires a refresh of arp) makes it actively connected.
Joined: 31 Jul 2021 Posts: 2146 Location: All over YOUR webs
Posted: Mon Jul 18, 2022 19:37 Post subject:
@puterboy2
You are correct but there is more to this than meets the eye.
Read this thread and specifically @brainslayers comments
However @puterboy2 dd-wrt build is old and ancient so the new code is not in place and you will only see the old behavior and cannot configure it to reflect the arp entries (at the loss of all bandwidth usage measurements where applicable).
Helpful comments... and I will upgrade my FW as soon as practical... (and yes I do use 'wl' extensively on my Broadcom router)
So it seems that the "Active Client" list intentionally has a longer cache of activity than dhcp or arp so as to be able to calculate average BW per MAC address... which is good for my purposes...
My question is which routine/script is called to generate the data as I would like to call it from the CLI.