Our ISP has supplied us with a Cisco router that is configured to forward email messages to the exchange server on our network. I called and told them that I am adding a firewall and they told me that they need to disable NAT on their router and that the firewall will need to be configured to handle this. Below is configuration of the router. How do I enable the firewall so that it will forward the messages to the exchange server once the NAT is disabled on the router. I have read throught the configuration guide and I can't figure out how to set this up. Thanks.
Current configuration for ISP's Cisco Router
ip subnet-zero
ip name-server 220.111.141.46
ip name-server 220.111.141.78
ip name-server 220.111.141.110
!
ip dhcp pool lan1
dns-server 76.153.243.48 76.153.243.49
!
!
!
!
interface Serial0
ip address xx.xx.xxx.155 255.255.255.252
no ip directed-broadcast
ip nat outside
encapsulation ppp
no fair-queue
service-module t1 timeslots 13-24
!
interface FastEthernet0
ip address xx.xx.xx.54 255.255.255.248 secondary
ip address 192.168.1.1 255.255.255.0
no ip directed-broadcast
ip nat inside
!
ip nat inside source list 1 interface Serial0 overload
ip nat inside source static tcp 192.168.1.17 25 76.154.186.55 25 extendable
ip nat inside source static tcp 192.168.1.17 110 76.154.186.55 110 extendable
ip classless
ip route 0.0.0.0 0.0.0.0 Serial0
ip route 0.0.0.0 0.0.0.0 76.154.116.150
no ip http server
!
access-list 1 permit 192.168.1.0 0.0.0.255
Current configuration for PIX Firewall
PIX Version 6.3(1)
interface ethernet0 auto
interface ethernet1 100full
nameif ethernet0 outside security0
nameif ethernet1 inside security100
enable password xxxxx encrypted
passwd xxxx encrypted
clock timezone CST -6
clock summer-time CDT recurring
fixup protocol ftp 21
fixup protocol h323 h225 1720
fixup protocol h323 ras 1718-1719
fixup protocol http 80
fixup protocol ils 389
fixup protocol rsh 514
fixup protocol rtsp 554
fixup protocol sip 5060
fixup protocol sip udp 5060
fixup protocol skinny 2000
fixup protocol smtp 25
fixup protocol sqlnet 1521
names
pager lines 24
mtu outside 1500
mtu inside 1500
ip address outside 76.154.186.56 255.255.255.248
ip address inside 192.168.1.254 255.255.255.0
ip audit info action alarm
ip audit attack action alarm
pdm location 192.168.0.1 255.255.255.0 inside
pdm logging informational 100
pdm history enable
arp timeout 14400
global (outside) 1 interface
nat (inside) 1 0.0.0.0 0.0.0.0 0 0
timeout xlate 0:05:00
timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 rpc 0:10:00 h225 1:00:00
timeout h323 0:05:00 mgcp 0:05:00 sip 0:30:00 sip_media 0:02:00
timeout uauth 0:05:00 absolute
aaa-server TACACS+ protocol tacacs+
aaa-server RADIUS protocol radius
aaa-server LOCAL protocol local
http server enable
http 192.168.1.0 255.255.255.0 inside
no snmp-server location
no snmp-server contact
snmp-server community public
no snmp-server enable traps
floodguard enable
telnet timeout 5
ssh timeout 5
console timeout 0
terminal width 80
Cryptochecksum:xxx
: end
