Zentyal Forum, Linux Small Business Server

Zentyal Server => Installation and Upgrades => Topic started by: darnoq on November 25, 2020, 02:50:50 pm

Title: Gmail connection DROP
Post by: darnoq on November 25, 2020, 02:50:50 pm

Hi,
I have issues with gmail on some workstations saying that there is no web connection or can't send email. Meantime google chat works fine. This happens sometimes like it was some king of flood protection in Zentyal (we are using gmail on number of workstations simultaniously). I have no firewall rule that blocks outbound 443, I even added special rule to allow to connect from LAN to any destination on Http and HTTPs (on top of stanrdard any/any/any in internal networks).  I do not use http proxy.

I have some dropped TCP packets from IP 172.217.16.5 (that's google's if I'm right) to local gateway, source port 443, destination  64429 but is that it?  Correting me if I'm wrong but adding a rule allowing all trafic from 443  is not a good idea?

Title: Re: Gmail connection DROP
Post by: darnoq on November 26, 2020, 01:45:36 pm

Update: The problem doesn't occur when client is connected through vpn. Now how is that possible?

Title: Re: Gmail connection DROP
Post by: doncamilo on November 27, 2020, 10:32:12 am

 :)

Use the iptables-save command to know the rules that iptables is applying:

Code: [Select]

sudo iptables-save
Zentyal introduces some hidden rules, study carefully the output of this command. I recommend you learn the use of the HPING3 program. It's invaluable in order to check firewalls.

Cheers!