ipfw is making contact with port 4021

Polytropon freebsd at edvax.de
Fri Jul 24 01:46:17 UTC 2020

On Thu, 23 Jul 2020 21:11:39 -0400, Ernie Luzar wrote:
> A firewall should not be making its own contact with any public ip 
> address. This is a security hole.

If ipfw should have done that - yes, that would be correct.
However, it is not the purpose of a firewall to contact
anything, anywhere, and ipfw has not done so in decades.
May I ask why you assume that ipfw is the problem here?
Do you have any specific logs or messages that you can
post to the list?

Sidenote: The IP belongs to alerts0.envisacor.com.
The homepage belongs to something called "Envisacor" which
states about itself that it is "a premiere ODM to the
Security and Home Automation industries" and is doing
"design including IP based-products". So maybe it's in
fact something in your network you bought from that
company that is phoning home?

Just guessing.

But at least it looks like a valid assumption...

> I have not played with ipfw since before it was rewritten to become 
> ipfw2 so I do not know when this internal "call home"  function was 
> added.


> Can any one provide any info about this?

If _you_ can provide some more information? :-)

Do you have any logs that show what is the originator of
the connection, what connection it is, and maybe if there
is some content transmitted? Tools like tcpdump or wireshark
can be helpful here. But if you have firewall logging,
maybe you can show some lines from the log related to
that IP address?

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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