Additional data point -- I've built temporary production FTP load balancers with CentOS 6, and they work properly. The firewall is disabled here too. Here's the "uname -a" output of the online machine:
Linux lb5 2.6.32-504.16.2.el6.centos.plus.x86_64 #1 SMP Wed Apr 22 00:59:31 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
Additional data point -- I've built temporary production FTP load balancers with CentOS 6, and they work properly. The firewall is disabled here too. Here's the "uname -a" output of the online machine:
Linux lb5 2.6.32- 504.16. 2.el6.centos. plus.x86_ 64 #1 SMP Wed Apr 22 00:59:31 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux