dovecot rejecting connects

[MIhai Badici]

On 12/21/19 2:50 AM, Bernd Petrovitsch wrote:
> Hi all!
>
> On Fri, 2019-12-20 at 17:39 -0700, Roy wrote:
> [...]
>> I created a new VM with Centos 8 and installed dovecot and postfix.
>> Postfix is working fine but dovecot rejects connections from anything
>> but the local machine.
>>
>> Locally
>>
>>     Trying 10.10.100.157...
>>     Connected to 10.10.100.157.
>>     Escape character is '^]'.
>>     * OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE
>> IDLE STARTTLS AUTH=PLAIN] Dovecot ready.
>>
>> Machine on same subnet.  Windows, Linux, etc.  Doesn't seem to matter
>>
>>     telnet 10.10.100.157 143
>>     Connecting To 10.10.100.157...
>>     Could not open connection to the host, on port 143: Connect failed
>>
>> I made sure the iptables are empty so it doesn't seem to be a firewall issue
> In the host or the VM?
> Is teh VM switchted or routed with the LAN interface?
>
>> I put some LOG statements in the iptables and it showed the connect
>> packet arriving and the response packet was ICMP type 3 code 13.
> Which make it pretty clear that it has nothing to do with
> dovecot as such as that's aresponse from the TCP/IP-stack ...
>
>> Any ideas?
> Duckduckgo-ing "icmp 3 13" delivers as the 1st link
> http://www.networksorcery.com/enp/protocol/icmp/msg3.htm and
> 13 seem to indicate "Communication Administratively Prohibited."
>
> Your turn;-)
>
> MfG,
> 	Bernd


CentOS 8 use nftables instead of iptables so first of all try 
firewall-cmd --list-services