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Pix DMZ DSL

Hi,

I try to get a small dmz working, with a smtp server, but no luck so far.

The topology looks like this:

LAN > Cisco Router > 506 > Bridged DSL

I have web access form the LAN, and I can access the smtp server in the dmz from the lan side.

But I can't get access from the outside to the smtp located in the dmz.

Any help would be greatly appreciated.

Here is my pix config:

PIX Version 6.3(4) interface ethernet0 auto interface ethernet1 auto nameif ethernet0 outside security0 nameif ethernet1 inside security100 enable password 8Ry2YjIyt7RRXU24 encrypted passwd 2KFQnbNIdI.2KYOU encrypted hostname pix domain-name abc123.com fixup protocol dns maximum-length 512 fixup protocol ftp 21 fixup protocol h323 h225 1720 fixup protocol h323 ras 1718-1719 fixup protocol http 80 fixup protocol pptp 1723 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 fixup protocol tftp 69 names name 10.10.10.25 SMTP access-list inside_access_in permit ip any any access-list inside_access_in permit icmp any any access-list outside_access_in remark SMTP access-list outside_access_in permit tcp any eq smtp any eq smtp pager lines 24 icmp permit any inside mtu outside 1500 mtu inside 1500 ip address outside pppoe setroute ip address inside 10.10.10.1 255.255.255.0 ip audit info action alarm ip audit attack action alarm pdm location 192.168.1.0 255.255.255.255 inside pdm location 192.168.1.0 255.255.255.0 inside pdm location SMTP 255.255.255.255 inside pdm location 60.60.60.60 255.255.255.255 outside pdm location 192.168.1.100 255.255.255.255 inside pdm history enable arp timeout 14400 global (outside) 1 interface nat (inside) 1 0.0.0.0 0.0.0.0 0 0 static (outside,inside) tcp SMTP smtp 60.60.60.60 smtp netmask

255.255.255.255 0 0 access-group outside_access_in in interface outside access-group inside_access_in in interface inside route inside 192.168.1.0 255.255.255.0 10.10.10.2 1 timeout xlate 3:00:00
Reply to
Alfy
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That only permits access when the source port is 25 and the destination port is 25. The source port is rarely 25 for smtp connections -- it is almost always a port from 1024 upwards.

That statement says that if you happen to receive a packet from the external host with IP address 60.60.60.60, and the source port for that packet is 25, then the *source* IP and port is to be translated to become 10.10.10.25 port 25, but the destination IP and port is to be left alone [except as modified by other statements in your configuration.] As you do not define what is to happen when the PIX receives a packet with a *destination* port of 25, the translated packet would be dropped, which is just as well as it would surely cause confusion with your internal host 10.10.10.25 .

If you want the dynamic IP address for your PIX to be the IP address that responds to smtp connections (and forwards the traffic to your internal host), then the appropriate statement would be

static (inside,outside) tcp interface smtp SMTP smtp netmask 255.255.255.255

If your ISP happens to route public IP 60.60.60.60 to you via your dynamically allocated external PIX IP (definitely not a common configuration!) and you wanted to respond to smtp attempts to 60.60.60.60 and this is NOT your PIX external IP address, then the appropriate statement would be

static (inside,outside) tcp 60.60.60.60 smtp SMTP smtp netmask 255.255.255.255

[Note to other possible readers: in these statements, SMTP in all capitals is a 'name' that the OP gave to 10.10.10.25, and is an arbitrary name; smtp in all lower-case in these statements is the PIX pre-defined port number 25.]
Reply to
Walter Roberson

Walter,

Thanks for the help.

The public ip is assigned to me by the isp.

So I should just remove the current statements and add:

static (inside,outside) tcp 60.60.60.60 smtp SMTP smtp netmask

255.255.255.255

Correct?

Thanks.

Reply to
Alfy

Please quote sufficient context so that people don't have to fire up a browser and hunt around in google for the previous posting.

If 60.60.60.60 is your PIX outside IP (i.e., you need to use pppoe for ADSL connection purposes even though your IP is fixed), then the above will not work and you must instead use

static (inside,outside) tcp interface smtp SMTP smtp netmask 255.255.255.255

(context for people following: SMTP is a 'name' the OP gave to an internal machine.)

Also, you must still have an ACL entry permitting the traffic. That entry should be either:

access-list outside2inside permit tcp any interface outside eq smtp if 60.60.60.60 is your PIX outside IP

or

access-list outside2inside permit tcp any host 60.60.60.60 eq smtp if 60.60.60.60 is an additional public IP that is not your PIX outside IP.

Reply to
Walter Roberson

Thanks a bunch. I'll give it a try.

Reply to
Alfy

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