By default, SELinux is configured to allow web servers to use the following ports.

~]# semanage port -l | grep ^http_port_t
http_port_t                    tcp      80, 81, 443, 488, 8008, 8009, 8443, 9000

Similarly, SELinux is configured to allow web servers to use the following ports for cache.

~]# semanage port -l | grep ^http_cache_port_t
http_cache_port_t              tcp      8080, 8118, 8123, 10001-10010
http_cache_port_t              udp      3130

The following command can be used to configure SELinux to allow your web server to use port 18080.

semanage port -a -t http_port_t -p tcp 18080

You should now see that port 18080 is allowed.

~]# semanage port -l | grep -w http_port_t
http_port_t                    tcp      18080, 80, 81, 443, 488, 8008, 8009, 8443, 9000