This sample configuration demonstrates how to set up the PIX Firewall for access to a mail server located on the inside network.
Note: The SMTP inspection configured in this document is not compatible with ESMTP connections to servers such as Microsoft Exchange. Do not configure SMTP inspection if you use a mail server that relies on ESMTP. Alternatively, PIX Software version 7.0 and later supports SMTP and ESMTP inspection.
There are no specific requirements for this document.
The information in this document is based on these software and hardware versions:
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
Refer to the Cisco Technical Tips Conventions for more information on document conventions.
In this section, you are presented with the information to configure the features described in this document.
Note: Use the Command Lookup Tool (registered customers only) to obtain more information on the commands used in this section.
This document uses this network setup.
This document uses these configurations.
| PIX Firewall
PIX Version 5.1(4)
!--- These commands name and set the security level for each PIX interface.
nameif ethernet0 outside security0
nameif ethernet1 inside security100
enable password 8Ry2YjIyt7RRXU24 encrypted
passwd 2KFQnbNIdI.2KYOU encrypted
fixup protocol ftp 21
fixup protocol http 80
fixup protocol h323 1720
fixup protocol rsh 514
fixup protocol smtp 25
fixup protocol sqlnet 1521
!--- Create an access list that permits SMTP traffic from anywhere !--- to the host at 220.127.116.11 (our server). The name of this list is !--- smtp. Add additional lines to this access list as required. !--- Note: There is one and only one access list allowed per !--- interface per direction (for example, inbound on the outside interface). !--- Because of limitation, any additional lines that need placement in !--- the access list need to be specified here. If the server !--- in question is not SMTP, replace the occurrences of SMTP with !--- www, DNS, POP3, or whatever else is required. The access-list !--- command was introduced in PIX Software Release 5.0; it is used !--- here instead of a conduit statement.
access-list smtp permit tcp any host 18.104.22.168 eq smtp
pager lines 24
no logging standby
logging console debugging
logging monitor debugging
logging buffered debugging
logging trap debugging
no logging history
logging facility 23
logging queue 512
!--- Set each Ethernet interface to auto-detect its media type.
interface ethernet0 auto
interface ethernet1 auto
mtu outside 1500
mtu inside 1500
!--- Define the IP address for each interface.
ip address inside 192.168.1.1 255.255.255.0
ip address outside 22.214.171.124 255.255.255.252
arp timeout 14400
!--- Specify that any traffic that originates inside from the !--- 192.168.2.x network NATs (PAT) to 126.96.36.199 if !--- such traffic passes through the outside interface.
global (outside) 1 188.8.131.52
nat (inside) 1 192.168.2.0 255.255.255.0
!--- Define a static translation between 192.168.2.57 on the inside and !--- 184.108.40.206 on the outside. These are the addresses to be used by !--- the server located inside the firewall.
static (inside,outside) 220.127.116.11 192.168.2.57 netmask 255.255.255.255
!--- Apply the access list named smtp inbound on the outside interface.
access-group smtp in interface outside
!--- Set the default route to 18.104.22.168. !--- The PIX assumes that this address is that of a router.
route outside 0.0.0.0 0.0.0.0 22.214.171.124 1
!--- Instruct the PIX to hand any traffic destined for 192.168.x.x !--- to the router at 192.168.1.2.
route inside 192.168.0.0 255.255.0.0 192.168.1.2 1
timeout xlate 1:30:00 conn 1:00:00 half-closed 0:10:00 udp 0:00:00
timeout rpc 0:10:00 h323 0:05:00
timeout uauth 0:00:00 absolute
aaa-server TACACS+ protocol tacacs+
aaa-server RADIUS protocol radius
no snmp-server location
no snmp-server contact
snmp-server community public
no snmp-server enable traps
terminal width 200
!--- Alternate command: !--- conduit permit tcp host 126.96.36.199 eq smtp any !--- The conduit command is equivalent to !--- the access-list statements this configuration shows. !--- In this case a path known as a conduit is created in order to allow any SMTP !--- traffic to host 188.8.131.52. Use of this command replaces the !--- access-list and access-group !--- statements that this configuration presents.
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
enable secret 5 $1$N0F3$XE2aJhJlCbLWYloDwNvcV.
!--- Sets the IP address of the Ethernet interface to 184.108.40.206.
ip address 220.127.116.11 255.255.255.252
!--- Instructs the serial interface to use !--- the address of the Ethernet interface when the need arises.
ip unnumbered ethernet 0
no ip address
no ip directed-broadcast
!--- Instructs the router to send all traffic !--- destined for 209.164.3.x to 18.104.22.168.
ip route 22.214.171.124 255.255.255.0 126.96.36.199
!--- Instructs the router to send !--- all other remote traffic out serial 0.
ip route 0.0.0.0 0.0.0.0 serial 0
line con 0
transport input none
line aux 0
line vty 0 4
exec-timeout 5 0
There is currently no verification procedure available for this configuration.
The logging console debugging command directs messages to the PIX console. If connectivity to the mail server is a problem, examine the console debug messages to locate the IP addresses of the sending and receiving stations in order to determine the problem.
| If you still need assistance after you complete the troubleshooting steps in this document and want to open a case with Cisco Technical Support, be sure to include this information for troubleshooting your PIX Firewall.
Attach the collected data to your case in non-zipped, plain text format (.txt). You can attach information to your case by uploading it with the TAC Service Request Tool (registered customers only) . If you cannot access the TAC Service Request Tool, you can send the information in an E-mail attachment to email@example.com with your case number in the subject line of your message.
- Problem description, which includes topology and IP address details of the mail server.
- Complete any troubleshooting before you open the case.
- Output from the show tech-support command.
- Output from the show log command after it runs with the logging buffered debugging command, or console captures that demonstrate the problem (if available)