Port forwarding using xinetd.

An easy method to do port forwarding without the iptables is to use the xinetd.
In order to port forward with xinetd, you will need to create a configuration file:

root# vim /etc/xinetd.d/imap_forward

For example: Forward port 143 on localhost to remote server on port 143:

service imap_forward
{
disable = no
type = UNLISTED
socket_type = stream
protocol = tcp
user = nobody
wait = no
redirect = remote_IP_or_server_name 143
port = 143
}