Re: ARP ping instead of ICMP ping for gateway latency check ?

[Michael Tremer <michael.tremer@ipfire.org>]

Hello Robin,

> On 20 Apr 2025, at 23:52, Robin Roevens <robin.roevens@disroot.org> wrote:
> 
> Hi All
> 
> I recently changed my internet provider and I noticed that both the
> gateway graph on cgi-bin/netother.cgi and my Zabbix gateway ping check
> no longer work.

Yes, some ISPs don’t respond do ICMP echo requests to the gateway. I have no idea why really, but it is not uncommon.

> It seems that my current provider blocks ICMP pings on the gateway
> address.
> So I was wondering if it wouldn't be better to use arping instead of
> normal ping to check the latency of the gateway? This should always
> works regardless of firewalls of the provider.. I think?

This is a good idea. An ARP ping should always work, because otherwise there is no way to discover the layer 2 address of the gateway. But that obviously only applies to internet connections that actually use ARP. PPP connections don’t use ARP for example.

We are also using collectd which is using liboping and that only supports ICMP.

> I can quite easily change this Zabbix check. But I'm not sure about the
> graph on netother.cgi; I can look into that if you all think that
> change would be a good idea? Or if anyone could give me some pointers
> on where to start looking?

I think so. It could be an option for the future.

If the gateway does not respond to pings, you should automatically fall back to ping.ipfire.org <http://ping.ipfire.org/> though. So the graph should always have some data to show.

Best,
-Michael

> 
> Regards
> Robin
> 
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