How do I customize the default rule that allows connection from all sources to port 8775 for nova-api service?

Issue

• I can see the default rule to port 8775 allows access from all sources.

# iptables -nvL | grep 877
 1977  166K ACCEPT     tcp  --  *      *       0.0.0.0/0            172.23.4.1          tcp dpt:8775

• I changed /etc/sysconfig/iptables to allow access to this port from only required sources and restarted iptables service. The new rule came into effect.

• But, when nova-api service was restarted next time, the custome rule is overwritten by the default rule which allows access from all sources by service restart.

How can I apply my custom rules to this port?