I have a physical CentOS 7 host (A) on my LAN (192.168.0.0/16). SElinux is disabled, and firewalld is disabled. It is the only changes I made from install defaults.
I have an other host (B) on that LAN; (B) has services like www, ssh, icmp.
At this step, I can play with (B) from (A):
$ ping *(B)* ... success ... $ curl google.com ... success ... $ curl *(B)* ... success ... $ mysql *(B)* ... success ...
Everything is running fine.
Now, I install Docker Community on (A):
$ yum check-update $ curl -fsSL https://get.docker.com/ | sh $ systemctl start docker
And now the results of such commands again on (A):
$ ping *(B)* ... success ... $ curl google.com ... success ... $ curl *(B)* ... Recv failure: Connection reset by peer ... $ mysql *(B)* ... Connection reset by peer ...
So basically, once Docker is setup and active, all TCPs connections from (A) (the host OR a docker container) to my LAN failed. Such error are likely to be a firewall issue, because TCPs connections from (B) to (A) are still available.
However I check iptables on (A) for REJECT rules or policies mistakes and there is absolutely nothing. I even clean iptables entirely on (A), and the problem still occur.
If all firewalls/security systems are disabled or empty of restrictives rules, and with permissives policies, I don't understand where is the problem and where I have to check on my CentOS system to solve the issue.
Could you please help ?