False positive on JSON file from Arduino

Viruses and worms
1

I just updated to the latest version of Avast (Free), and - with the web shield up - I am now not able to visit an Arduino device in the local network. I access the device by its fixed IP-address (192.168.178.101) and all it returns (or at least it should) is a JSON data string (Content-Type header set to text/html, just a single layer with key:value pairs).

I have tried every setting in the web shield settings, and added the IP-address to both the general exclusion list as the one for the web shield, but the only way to get it working again is to disable to complete web shield …

Avast didn’t give any warning about blocking this ‘website’ (maybe because this is a multi-concurrent-user machine, messages are most of the times only showed in the admin session, which runs some programs that can not run as a service). I already did a complete re-install.

Any suggestions?

2

JSON string:

{“time”:10448453,“solarIn”: 9.766,“solarOut”: 20.508,“solarPump”:0,“solarMax”:0,“solarHot”:0,“waterOut”: 19.531,“waterMax”: 20.318,“washerPower”: 0.000,“washerStart”:0,“washerMode”:50,“washerRinse”:0,“ventStatus”:0,“ventTurnOff”:0}

Headers:

Content-Type: text/html
Pragma: no-cache

3

avast very recently fixed a problem in the firewall, but it seems that kinda the same problem has slipped into the web shield at the same time.
Nothing we can do about it here on this webboard.
You might want to tell avast about it > https://support.avast.com (create a ticket)

4

Will do.

Just noted that another Arduino is also blocked:

{“time”:1775788590}

But this one isn’t:

{“status”: “ok”, “mode”: 0,“special”: 0,“count”: 65535,“interval”: 1500}

All the same headers.
Maybe it has something to do with the spacing?

5

It can, but I doubt it has to do with the spacing.
But only someone from avast can tell.

6

Got a reply from support, and investigated a little further. Seems like the FIN+ACK is not coming through with the shield up. Instead somebody starts sending Keep-Alive’s keeping the client waiting, resulting in a time-out.

Difference between Arduino’s probably due to a difference in HTTP library used.

Will wait for response from support.