Follow these steps to add a rule to iptables to allow incoming connections on port 9998:
Edit iptables:
# vi /etc/sysconfig/iptables
Find the following line in the file:
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
Add the following line BEFORE the above line:
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 9998 -j ACCEPT
Restart iptables:
# service iptables restart