[CentOS] ssh failure from CentOS7 to Centos6

Sat Jan 18 18:32:22 UTC 2020
Patrick Bégou <Patrick.Begou at legi.grenoble-inp.fr>

Thanks all for your answers ans suggestions. It cannot be a fail2ban
problem as firewall was disabled on the server for the tests.

The time was playing against me so I went back to centos6 (these
desktops must be available monday) and all run fine. I will investigate
this later. It's easy for me to switch from Centos6 to Centos7 as the OS
is automatically installed (PXE boot + Kickstart)