Wi-fi in Access Point mode

[Renato75]

Hi Armin, before wasting hours in testing, I don't remember if I can connect via AccessPoint to the Gateway and then I can ping an instrument on the Eth0 network.
Once connected to the access point, I can ping the IP address of Eth0 but not the instrument on the same network as the Eth0 port.
Do I need to enter any rules?
Could this thing be done in both the netPI and an Edge Gateway?
Thanks.

[Armin@netPI]

To be honest I am not a networking specialist so I don't know what all is needed in all details.

I remember I had tested such a constellation once and one thing I remember was to enable in the firewall setting to set the eth0 interface to status "trusted". Then with an active access point you should be able to ping devices in the eth0 subnet from a PC for example that is connected to this access point as a client.

[Renato75]

Thanks Armin, yes, the default firewall setting is already set to Trusted.

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Hi Armin, I found an old question from a customer, it seems that the IP addresses set in the access point must be completely different from those set in the Eth0 port.
So if the Eth0 port is set as IP: 192.168.2.1 and the SubNet: 255.255.255.0 the Wifi Access Point port "must" be IP: 17.100.4.16 Subnet: 255.255.0.0.
This way it works but I don't know why, my skills stop there, as a client of mine says: I'm a technician up to the curve... :-)
Thanks as always for your availability.

[Armin@netPI]

Well, thank you Renato for letting us all know that it works the way I described it.

Two physical interfaces with the very same IP network address room/pool will never work in general. This has nothing to do with netPI and wifi and eth0 doing parallel communications. This is just basic IP networking practice and knowledge in my eyes.

[Steph]

Thanks Armin, yes, the default firewall setting is already set to Trusted.

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Hi Armin, I found an old question from a customer, it seems that the IP addresses set in the access point must be completely different from those set in the Eth0 port.
So if the Eth0 port is set as IP: 192.168.2.1 and the SubNet: 255.255.255.0 the Wifi Access Point port "must" be IP: 17.100.4.16 Subnet: 255.255.0.0.
This way it works but I don't know why, my skills stop there, as a client of mine says: I'm a technician up to the curve... :-)
Thanks as always for your availability.

Dear Renato

I just tried the same and it does not work even with the values, which you proposed. Just once more for clarification: I want to be able to access devices connected to eth0 of the netPI via wlan0, for example with a tablet. But I could not even reach eth0 with all tried settings and also not the devices connected to eth0 with a switch. Did you manage to do so?
I hope that you or Armin will reply to this old topic.
I have attached to this mail the values I entered according to your suggested values, while I have also tested other values without success.

@Armin: Is it possible that the netPI does not automatically route internally from eth0 to wlan0?

Thanks in advance for your answers.


  ValuesAccToRenato.pdf (Size: 225.78 KB / Downloads: 2)

[Armin@netPI]

Well Steph,

I don't know if it is possible with netPI since it does not support port forwarding. But as I said before I am no networking expert.

I analysed your PDF. Supposing you connect you Wifi tablet to the netPI Wifi access point ...  then it would get an IP address in the range from 17.100.4.80 to 89. 

In the most simpliest case it would get the first ip address 17.100.8.80 through netPI's Wifi DHCP server, right? Also your Wifi tablet should automatically receive a gateway address through the same netPI Wifi DHCP server. Which one is it? Is it 17.100.8.16 which is the Wifi IP address of netPI? The gateway address in your tablet is the first most relevant value to know to let the routing table in your tablet know where to send a ping to e.g. 192.168.1.100 to. Cause any IP address that is not in any known subnet will be sent to the default gateway which must be the netPI IP address. Else not even the ping ethernet frame is leaving your tablet at all.

Thx
Armin

[Steph]

Well Steph,

I don't know if it is possible with netPI since it does not support port forwarding. But as I said before I am no networking expert.

I analysed your PDF. Supposing you connect you Wifi tablet to the netPI Wifi access point ...  then it would get an IP address in the range from 17.100.4.80 to 89. 

In the most simpliest case it would get the first ip address 17.100.8.80 through netPI's Wifi DHCP server, right? Also your Wifi tablet should automatically receive a gateway address through the same netPI Wifi DHCP server. Which one is it? Is it 17.100.8.16 which is the Wifi IP address of netPI? The gateway address in your tablet is the first most relevant value to know to let the routing table in your tablet know where to send a ping to e.g. 192.168.1.100 to. Cause any IP address that is not in any known subnet will be sent to the default gateway which must be the netPI IP address. Else not even the ping ethernet frame is leaving your tablet at all.

Thx
Armin

Dear Armin,

everything works now as I want it to work.

You reminded me to eliminate my standard gateway of my other ethernet interface on my PC (off course not necessary on my tablet, because it does not has a standard gateway).
In adddition, it seems that the netPI deactivates eth0 if nothing is connected to it so I could not reach it, before I connected it to a network.
And in my PLC (an S7-1516) I had also to configure to use a router for the interface and the router address has to be the address of eth0 of the netPI. 

After connecting to the WLAN of the netPI I can now ping wlan0 and eth0 of the netPI as well as the ethernet interface of my PLC.

So now I can reach the OPC UA-Server on the PLC out of nod-red on the netPI as well as out of an OPC UA Client on my tablet. I can reach node-red from the netPI and the dasboards from my browser in the tablet. I can also reach the webserver of my PLC out of a browser on the tablet. Additionally, which was not needed, I can reach all from my PC.
It sounds a bit redundant but this is for didactic reasons.

Thanks a lot
  Stephan

[Armin@netPI]

Thank you Steph for letting me know.