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how to nat mail exchange server trought a cisco827 adsl

--begin ciscomoderator note-- The following post has been edited to remove potentially confidential information. Please refrain from posting confidential information on the site to reduce security risks to your network. -- end ciscomoderator note --

i have a cisco 827 cofigured for adsl connection and 16 public ip address

in my lan i have a mail server (exchange server ) this server have the ip and use the port 25 i want to give a public ip for this server and the other for the other pc in my lan for that i used dynnamic nat and static nat at the same time but i cant connect to the mail server from a public ip just work on the lan

here is the configuration for the router and please help me and thank you very much !!

Router#sh run

Building configuration...

Current configuration : 1622 bytes


version 12.1

no service single-slot-reload-enable

no service pad

service timestamps debug uptime

service timestamps log uptime

service password-encryption


hostname Router


logging rate-limit console 10 except errors

aaa new-model

enable secret 5 xxxxxxxxxxxxxxxxx


username Router password 7 xxxxxxxxxxxx

mmi polling-interval 60

mmi auto-configure

no mmi pvc

mmi snmp-timeout 180

ip subnet-zero

no ip finger

no ip domain-lookup


ip dhcp pool client

import all




no ip dhcp-client network-discovery




interface Ethernet0

ip address secondary

ip address yy.yy.yy.177

ip nat inside

hold-queue 32 in


interface ATM0

no ip address

no atm ilmi-keepalive

pvc 0/16 ilmi



dsl operating-mode auto


interface ATM0.1 point-to-point

ip address nn.nn.nn.210

ip nat outside

pvc 8/35

vbr-nrt 640 640 1

encapsulation aal5snap



ip classless

ip route ATM0.1

no ip http server


ip nat pool Router yy.yy.yy.179 yy.yy.yy.190 netmask

ip nat inside source list 1 pool Router

ip nat inside source static yy.yy.yy.178

ip nat inside source static tcp 25 yy.yy.yy.178 25 extendable

access-list 1 deny

access-list 1 permit

access-list 101 deny tcp any any eq telnet

snmp-server manager


line con 0

transport input none

stopbits 1

line vty 0

password 7 xxxxxxxxxxxx

line vty 1 3

access-class 101 in

line vty 4

access-class 101 in

access-class 101 out


scheduler max-task-time 5000


  • Other Security Subjects

Re: how to nat mail exchange server trought a cisco827 adsl

From my reply on the WAN/Routing/Switching Forum:

Hi -

All you need to know about config of NAT on c827 etc is here >


Hope this helps --