ip address 172.20.128.1 255.255.255.0
ip route 172.20.0.0 255.255.240.0 172.20.128.254
ip nat inside source static tcp 172.20.128.12 25 interface Dialer0 25
access-list 101 permit ip 172.20.128.0 0.0.0.255 any
access-list 101 permit ip 172.20.0.0 0.0.1.255 any
access-list 103 deny   ip 192.168.0.0 0.0.255.255 any
access-list 103 deny   ip 172.0.0.0 0.31.255.255 any
access-list 103 deny   ip 127.0.0.0 0.255.255.255 any
access-list 103 deny   ip 10.0.0.0 0.255.255.255 any
access-list 103 deny   ip host 255.255.255.255 any
access-list 120 permit ip 172.20.0.0 0.0.15.255 any
access-list 120 permit ip 172.20.128.0 0.0.0.255 any
access-list 123 permit tcp 172.20.128.0 0.0.0.255 any eq telnet