>
>ip nat inside source static tcp 172.16.x.x 53 interface FastEthernet0/0 53
>
>может и так ?

Current Configuration:
!
version 12.1
service timestamps debug uptime
service timestamps log uptime
!
hostname 827
!
ip subnet-zero
no ip domain-lookup
!
bridge irb
!
interface Ethernet0
ip address 192.168.0.254 255.255.255.0
ip nat inside

!--- This is the inside local IP address and it is a private IP address.

!
interface ATM0
no ip address
no atm ilmi-keepalive
pvc 0/35
encapsulation aal5snap
!
bundle-enable
dsl operating-mode auto
bridge-group 1
!
interface BVI1
ip address 171.68.1.1 255.255.255.240
ip nat outside

!--- This is the inside global IP address.
!--- This is your public IP address and it is provided to you by your ISP.

!
ip nat inside source list 1 interface BVI1 overload

!--- This statement makes the router perform PAT for all the
!--- End Stations behind the Ethernet interface that  uses
!--- private IP addresses defined in access list #1.

ip nat inside source static tcp 192.168.0.5 80 171.68.1.1 80 extendable

!--- This statement performs the static address translation for the Web server.
!--- With this statement, users  that try to reach 171.68.1.1 port 80 (www)  are
!--- automatically redirected to 192.168.0.5 port 80 (www). In this case
!--- it is the Web server.

ip classless
ip route 0.0.0.0 0.0.0.0 171.68.1.254

!--- IP address 171.68.1.254 is the next hop IP address, also
!--- called the default gateway.
!--- Your ISP can tell you what IP address to configure as the next hop address.

!
access-list 1 permit 192.168.0.0 0.0.0.255

!--- This access list defines the private network
!--- that  is network address translated.

bridge 1 protocol ieee
bridge 1 route ip
!
end
вот ещё.