When installing Oracle 12c RAC, the Grid Installer fails with:
Specified network interface doesn't maintain connectivity across cluster nodes.
This error is caused when the Linux firewall is still operational.
Log in as root, shutdown and disable the firewall on all nodes of the cluster:
[root@ora12a ~]# service iptables stop iptables: Flushing firewall rules: [ OK ] iptables: Setting chains to policy ACCEPT: filter [ OK ] iptables: Unloading modules: [ OK ] [root@ora12a ~]# chkconfig iptables off
Now retry the Grid installer step and it should succeed.
the gruffdba 
I am trying to install 12c grid infrastructure on RHEL 5.8 /INS 41112 error occurred. How to rectify ? this solution is not working for me 😦
Nikhil,
The INS 41112 error is a generic networking message, so its a bit tricky to track it down. Make sure you can ping all addresses from both nodes and that you have created the ssh keys to share the oracle password between nodes.
Thank you very much. Two years after publishing, your post was very useful. I kept re-checking interfaces and they were all correct, and all links except yours instructed to check network interfaces. Thanks again.
Thank you so much for this article. This solved our issue