Update :You already mentioned that you could ping the server so I assumed firewall is disabled. Can you access the main login page now?
I also went through this thread Access R12 Instance from Host(Win 7,64 Bit): Installed on Guest (OEL5) and disabled the firewall in Linux server as mentioned in [ID 457458.1]
1. Edit /etc/selinux/config
Change the SELINUX value to "SELINUX=disabled".
Reboot the server.