Problems getting 4g Dongle to work

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Rassiloth
Posts: 20
Joined: Thu Feb 07, 2019 4:35 pm

Re: Problems getting 4g Dongle to work

Post by Rassiloth » Fri Feb 15, 2019 4:47 pm

Colin,

Not quite.

On the client workstation, I can't get to anywhere (including the SkipperMate site).

What I can get to is the local BCS portal (192.168.51.254).

What does work is the 'Check broadband Connection' on that portal. I assume this runs a process on the BCS itself to contact your main system and report back the IP address used.

On the BCS itself all traceroutes work (whether the dns names or to ip addresses)
On the desktop client traceroutes to addresses other than the BCS interfaces fail.

For example the command traceroute 8.8.8.8 gives:

traceroute to 8.8.8.8 (9.9.9.9), 30 hops max, 60 byte packets
1 192.168.51.254 (192.168.51.254) 7.987 ms 8.201 ms 8.359 ms
2 *.*.*
3 *.*.*

The last lines repeat till the 30 hops expires.

My gut feeling is to look at the $G dongle as the issue. It does not appear to know how to root packets back to the 192.168.51.0/24 subnet

Unfortunately I have no info on how to confirm/disprove this.


Ian

Rassiloth
Posts: 20
Joined: Thu Feb 07, 2019 4:35 pm

Re: Problems getting 4g Dongle to work

Post by Rassiloth » Fri Feb 15, 2019 5:03 pm

Colin,

Or its a NAT issue and the BCS is not 'natting' traffic heading to the 4G dongle.


Ian

Rassiloth
Posts: 20
Joined: Thu Feb 07, 2019 4:35 pm

Re: Problems getting 4g Dongle to work

Post by Rassiloth » Fri Feb 15, 2019 5:20 pm

Colin,

a tcpdump on the eth1 interface shows that the BCS is sending the traffic from the internal client to the 4G dongle without applying any source nat.

This does not happen when on WiFi where packets are source natted behind the BCS's external address.


Ian

crb
Site Admin
Posts: 52
Joined: Mon Oct 10, 2016 1:08 pm

Re: Problems getting 4g Dongle to work

Post by crb » Fri Feb 15, 2019 7:52 pm

Beats me too. We use the system for all our work through the summer using a 4G dongle with no problems. I'll see if I can dig out some info on your dongle.

It might be worth looking at the skippers mate section in dhcpd.conf but I'd be surprised if it has changed. Post it here if it doesn't seem to make sense.

I assume that there is no other dhcp (or DNS) server on your network.

Take a look at resolv.conf - it should have a sensible name server for your network. Try changing the name server to 8.8.8.8 and then browsing.

Colin

Rassiloth
Posts: 20
Joined: Thu Feb 07, 2019 4:35 pm

Re: Problems getting 4g Dongle to work

Post by Rassiloth » Sat Feb 16, 2019 10:39 am

Colin,

First thing. Its all now working ;-)

Second what was up.

It was all tied up in NAT.

Dumping the ip tables config into a file showed that their was only postrouting masquerade set for eth0, usb0 and wlan1

applying one for eth1 fixes the issue.

I've added this as a permanent thing and all is now fine.

Incidentally removing the one for usb0 appears to have fixed my intermittent GPS issue as well.

Next up is fixing those sensors.

crb
Site Admin
Posts: 52
Joined: Mon Oct 10, 2016 1:08 pm

Re: Problems getting 4g Dongle to work

Post by crb » Sun Feb 17, 2019 11:39 am

Ah, I made an incorrect assumption that there would be no hard wired lan so the dongle would always be eth0. Not so in your case. My apologies - I'll see that the documentation is updated. I assume that when you install on the boat you'll have only the dongle and not the wired lan. If this is the case it would probably be worth removing both eth entries from /etc/udev/rules.d/70-persistent-net.rules so that your dongle appears as eth0.

Glad you have it working.

Cheers,
Colin

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