Autenticazione proxy in entrata - Nessuna configurazione Cisco IOS Firewall o NAT

Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname security-3640
!

!--- Turn on authentication.

aaa new-model

!--- Define the server group and servers for TACACS+ or RADIUS.

aaa group server tacacs+|radius RTP
 server 171.68.118.115
!

!--- Define what you need to authenticate.

aaa authentication login default group RTP none
aaa authorization exec default group RTP none
aaa authorization auth-proxy default group RTP
enable secret 5 $1$H9zZ$z9bu5HMy4NTtjsvIhltGT0
enable password ww
!
ip subnet-zero
!

!--- You want the router name to appear as banner.

ip auth-proxy auth-proxy-banner

!--- You want the access-list entries to timeout after 10 minutes.

ip auth-proxy auth-cache-time 10

!--- You define the list-name to be associated with the interface.

ip auth-proxy name list_a http
ip audit notify log
ip audit po max-events 100
cns event-service server
!
process-max-time 200
!
interface FastEthernet0/0
 ip address 40.31.1.150 255.255.255.0
 no ip directed-broadcast
 no mop enabled
!
interface FastEthernet1/0
 ip address 11.11.11.11 255.255.255.0

!--- Apply the access-list to the interface.

ip access-group 115 in
 no ip directed-broadcast

!--- Apply the auth-proxy list-name.

 ip auth-proxy list_a
!
ip classless
ip route 171.68.118.0 255.255.255.0 40.31.1.1

!--- Turn on the http server and authentication.

ip http server
ip http authentication aaa
!

!--- This is our access-list for auth-proxy testing - !--- it denies only one host, 11.11.11.12, access - to minimize disruption !--- to the network during testing.

access-list 115 permit tcp host 11.11.11.12 host 11.11.11.11 eq www
access-list 115 deny   icmp host 11.11.11.12 any
access-list 115 deny   tcp host 11.11.11.12 any
access-list 115 deny   udp host 11.11.11.12 any
access-list 115 permit udp any any
access-list 115 permit tcp any any
access-list 115 permit icmp any any
dialer-list 1 protocol ip permit
dialer-list 1 protocol ipx permit
!

!--- Define the server(s).

tacacs-server host 171.68.118.115
tacacs-server key cisco
radius-server host 171.68.118.115
radius-server key cisco
!
line con 0
 transport input none
line aux 0
line vty 0 4
 password ww
!
!
end