Enter the command line using telnet with the admin account.

Here we define a port-forward rule named my-ssh which will redirect the external TCP/59722 port of the router to the internal host 192.168.1.3, TCP/22 port:

DLINK# configure 
DLINK(cfg)# nat 
DLINK(cfg-nat)# add portmapping my-ssh
DLINK(cfg-nat)# portmapping my-ssh
DLINK(cfg-nat-portmap:ssh-IPBOX)# extPortList add TCP:59722
DLINK(cfg-nat-portmap:ssh-IPBOX)# host 192.168.1.3
DLINK(cfg-nat-portmap:ssh-IPBOX)# intPort 22
DLINK(cfg-nat-portmap:ssh-IPBOX)# allInterfaces enable
DLINK(cfg-nat-portmap:ssh-IPBOX)# enable
DLINK(cfg-nat-portmap:ssh-IPBOX)# show
DLINK(cfg-nat-portmap:ssh-IPBOX)# configSave