[CentOS] CentOS 8: two external network adapters, two ISPs - routing problems

Mon Aug 2 07:45:01 UTC 2021
Roberto Ragusa <mail at robertoragusa.it>

On 7/30/21 4:27 PM, Konstantin Boyandin via CentOS wrote:

> Current situation:
> - All services forwarded from eth0 are working normally.
> - All traffic originating from intranet passes out and back normally.
> - All the attempts to access services from eth2 time out.
> There are no obvious hints in /var/log/messages (such as complaints
> about "martian IPs").
> I am somewhat at a loss here, all the pieces of advice would be very
> welcome.

The setup looks reasonable at first sight, and it is similar to what I have (on a C7).
Have you tried some tcpdump on the interfaces?
If the src-based routing rules are not working well, it happens that
your answers go out the wrong ethernet and nothing works (especially if your
provider doesn't want to forward what looks like spoofed packets).


    Roberto Ragusa    mail at robertoragusa.it