i have 3 port lan
eth 1 with cablemodem dynamic ip
eth 2,3 free to conect 2 pc
i need to nat and make dhcp
that's all

configuracion basica mikrotik

primero dar de alta port lan con internet
caso ip dinamica (emulacion router linksys generico)

ip-- dhcp client
add eth3 (puerto que va a tener internet)

ir a bridge
solapa bridge
add one

bridge --- ports
add eth1
add eth2
add wlan

ip--- dns
add one
poner ip del dhcp
despues ir a setting
poner esto dns1 200.42.0.111

ip --- address
add 192.168.1.1/24 IMPORTANTE /24
seleccionar bridge en interface

ip dhcp server
click on dhcp setup
dhcp server interface BRIDGE
dhcp address space 192.168.1.0/24
gateways for dhcp network 192.168.1.1
address to give out 192.168.1.2-192.168.1.254
dns 1 200.42.0.111
dns 2 200.42.0.109

ip ---- firewall
add one rule
chain SRCNAT
out interface ETH3

ACTION
masquerade