ipfw disable one_pass
ipfw pipe 10 config bw 36Kbits/s
ipfw add 50 pipe 10 all from 192.168.220.5 to any 1021-3388
ipfw add 50 pipe 10 all from any 1021-3388 to 192.168.220.5
ipfw add 50 pipe 10 all from 192.168.220.5 to any 3390-3455
ipfw add 50 pipe 10 all from any 3390-3345 to 192.168.220.5
ipfw add 50 pipe 10 all from 192.168.220.5 to any 3458-6899
ipfw add 50 pipe 10 all from any 3458-6899 to 192.168.220.5
ipfw add 50 pipe 10 all from 192.168.220.5 to any 6903-8900
ipfw add 50 pipe 10 all from any 6903-8900 to 192.168.220.5

ipfw add allow tcp from 192.168.220.5 to not me src-addr 15

Funciona.