Date: 20-01-05 19:37
Why it needs -dynamic is simple : natd must translate private IP addresses to the public IP address. So, natd must KNOW what your public IP is.
natd looks at the interface IP address when it starts. So, if your start dhclient after natd, the address will change. And if your dhcp lease expires, your address will change too. So you must tell natd to look for IP address changes on your public interface.
-dynamic If the -n or -interface option is used, natd will monitor the
routing socket for alterations to the interface passed. If
the interface's IP address is changed, natd will dynamically
alter its concept of the alias address.