Re: [Dorset] Monitor Pings on WiFi Interface

[Victor Churchill]

That's good to hear!

best regards,
웃
Victor Churchill,
Netley Abbey, Southampton



On Fri, 28 May 2021 at 14:51, Terry Coles  wrote:

> On Friday, 28 May 2021 13:21:47 BST Terry Coles wrote:
> > It's lunchtime just now, so I'll try it at WMT later.
>
> That worked well.  The pings showed up every 15 minutes :-)
>
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Re: [Dorset] Monitor Pings on WiFi Interface

[Terry Coles]

On Friday, 28 May 2021 13:21:47 BST Terry Coles wrote:
> It's lunchtime just now, so I'll try it at WMT later.

That worked well.  The pings showed up every 15 minutes :-)

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Re: [Dorset] Monitor Pings on WiFi Interface

[Terry Coles]

On Friday, 28 May 2021 13:10:08 BST Victor Churchill wrote:
> As I recall (it's a while since I used either) wireshark is itself built on
> top of a CLI tool tcpdump  which I
> imagine you should be able to install on a Pi on your network. It has a
> raft full of more options than you ever thought you migh tneed and the
> trick will be narrowing down what it captures to what you are interested
> in. Simply saying
> $ tcpdump host 192.168.0.253
> should show you what's happening.

Victor,

I reckon that's the one.  I've just tried it on my local network with an 
interval time of 10 seconds and it's working fine.

It's lunchtime just now, so I'll try it at WMT later.

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Re: [Dorset] Monitor Pings on WiFi Interface

[Patrick Wigmore]

On Fri, 28 May 2021 12:17:38 +0100, Terry Coles wrote:
> I'm coming to believe that I can only capture packets between two
> devices on a  network if I am actually running the tool from a
> device on that network rather than from a remote device over
> VPN.  None of the Pis on the WMT network are running X.
> 
> I could of course run wireshark from the command line on one of the
> devices on  the WMT network, so I'm wondering if Smokeping somehow
> gets round the problem and allows me to monitor data from my PC.

The thing to bear in mind is that networks tend to avoid sending 
packets where they are not needed. Switches do that based on MAC 
addresses and routers do it based on IP addresses. (Things like VPN 
servers, VPN clients, and some WiFi access points can also be regarded 
as routers if you look at them through this lens.)

In principle you could reconfigure the network to send all the packets 
via your home computer, and capture them that way, but you don't want 
to do that.

Is there any reason why you can't just log the output of your ping 
script into a file? That should give you all the information you're 
looking for.

Alternatively, capturing packets on the Pi should work.

tcpdump seems to be the usual command for capturing packets without a 
GUI. (If I remember correctly, the name is misleading and it isn't 
limited to just TCP.)

Wireshark can open tcpdump capture files if you prefer to review them 
using a GUI.

Patrick

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Re: [Dorset] Monitor Pings on WiFi Interface

[Victor Churchill]

Hi Terry,
As I recall (it's a while since I used either) wireshark is itself built on
top of a CLI tool tcpdump  which I
imagine you should be able to install on a Pi on your network. It has a
raft full of more options than you ever thought you migh tneed and the
trick will be narrowing down what it captures to what you are interested
in. Simply saying
$ tcpdump host 192.168.0.253
should show you what's happening.

best regards,
웃
Victor Churchill,
Netley Abbey, Southampton



On Fri, 28 May 2021 at 13:01, Terry Coles  wrote:

> On Friday, 28 May 2021 12:33:53 BST Terry Coles wrote:
> > On Friday, 28 May 2021 12:25:27 BST Keith Edmunds wrote:
> > > Smokeping is a daemon, so no X needed. The (optional) display is
> simply a
> > > web page, so no X needed. The notifications don't need X.
>
> Keith,
>
> Maybe I'm missing something, but this tool doesn't seem to do what I
> need.
> From the Introduction:
>
> 'Smokeping is a latency measurement tool. It sends test packets out to the
> net
> and measures the amount of time they need to travel from one place to the
> other and back.'
>
> I don't need a tool to send out packets; my Pi is already doing that (I
> hope).
> I need a tool to monitor packets being sent by one host on a network to
> another as Wireshark does.
>
> Or am I being dumb?
>
> --
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>
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Re: [Dorset] Monitor Pings on WiFi Interface

[Terry Coles]

On Friday, 28 May 2021 12:33:53 BST Terry Coles wrote:
> On Friday, 28 May 2021 12:25:27 BST Keith Edmunds wrote:
> > Smokeping is a daemon, so no X needed. The (optional) display is simply a
> > web page, so no X needed. The notifications don't need X.

Keith,

Maybe I'm missing something, but this tool doesn't seem to do what I need.  
From the Introduction:

'Smokeping is a latency measurement tool. It sends test packets out to the net 
and measures the amount of time they need to travel from one place to the 
other and back.'

I don't need a tool to send out packets; my Pi is already doing that (I hope).  
I need a tool to monitor packets being sent by one host on a network to 
another as Wireshark does.

Or am I being dumb?

-- 



Terry Coles



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Re: [Dorset] Monitor Pings on WiFi Interface

[Terry Coles]

On Friday, 28 May 2021 12:25:27 BST Keith Edmunds wrote:
> Smokeping is a daemon, so no X needed. The (optional) display is simply a
> web page, so no X needed. The notifications don't need X.

Keith,

Right.  I see that it is available in the Raspberry Pi Repos, so I guess I 
need to look at the documentation to work out the incantation needed to 
monitor ping traffic from the suspect Pi.

I have about 20 other Pis on the network to choose from as a host for the 
tool.  :-)

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Re: [Dorset] Monitor Pings on WiFi Interface

[Keith Edmunds]

Smokeping is a daemon, so no X needed. The (optional) display is simply a
web page, so no X needed. The notifications don't need X.
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Re: [Dorset] Monitor Pings on WiFi Interface

[Terry Coles]

On Friday, 28 May 2021 11:58:43 BST Keith Edmunds wrote:
> Smokeping is your friend: https://oss.oetiker.ch/smokeping/
> 
> Demo: https://oss.oetiker.ch/smokeping-demo/?target=Customers.OP

Keith,

That looks like its a graphical tool by default, although I see that there is 
a command line mode.

I'm coming to believe that I can only capture packets between two devices on a 
network if I am actually running the tool from a device on that network rather 
than from a remote device over VPN.  None of the Pis on the WMT network are 
running X.

I could of course run wireshark from the command line on one of the devices on 
the WMT network, so I'm wondering if Smokeping somehow gets round the problem 
and allows me to monitor data from my PC.

(Maybe I'm just using Wireshark wrong :-)  It wouldn't surprise me.)

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Terry Coles



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Re: [Dorset] Monitor Pings on WiFi Interface

[Keith Edmunds]

Smokeping is your friend: https://oss.oetiker.ch/smokeping/

Demo: https://oss.oetiker.ch/smokeping-demo/?target=Customers.OP

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[Dorset] Monitor Pings on WiFi Interface

[Terry Coles]

Hi,

I've been having a problem at Wimborne Model Town with a WiFi connection that 
appears to go down periodically.  One possible solution is that the WiFi 
Adaptor uses WMM Power.  This feature has been known to cause trouble with 
devices that sit on a network with little or no traffic for many days.  The 
solution suggested by the guys at the Raspberry Pi Forums is to set up a 
script on the Pi with the problematic interface to ping something else on the 
network, so I've used a simple ping command in a script started at boot-up: