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Cannot query DNS Servers inside from DMZ on Cisco PIX

Posted on 2005-05-11
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Last Modified: 2013-11-16
I hope this is in the right place:

I have an issue with DNS on windows, I am pretty sure my PIX configuration is correct.  The problem is; hosts on my DMZ cannot use internal DNS servers running on a Windows Server 2003 machine.  I am not able to resolve internal host names because of it.  All recursive queries appear to be dropped.

Here is my firewall config:

: Saved
: Written by enable_15 at 08:40:51.532 UTC Wed May 11 2005
PIX Version 6.3(4)
interface ethernet0 auto
interface ethernet1 auto
interface ethernet2 auto
interface ethernet3 auto shutdown
interface ethernet4 auto shutdown
interface ethernet5 auto shutdown
nameif ethernet0 outside security0
nameif ethernet1 inside security100
nameif ethernet2 DMZ1 security4
nameif ethernet3 intf3 security6
nameif ethernet4 intf4 security8
nameif ethernet5 intf5 security10
enable password ylXiDWg/AveJg/8c encrypted
passwd 2KFQnbNIdI.2KYOU encrypted
hostname
domain-name
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 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
access-list outside_in permit icmp any any echo-reply
access-list outside_in permit icmp any any unreachable
access-list outside_in permit icmp any any time-exceeded
access-list outside_in permit tcp any host xxx.xxx.xxx.83 eq smtp
access-list outside_in permit tcp any host xxx.xxx.xxx.83 eq https
access-list outside_in permit tcp any host xxx.xxx.xxx.83 eq www
access-list outside_in permit tcp any host xxx.xxx.xxx.90 eq ftp-data
access-list outside_in permit tcp any host xxx.xxx.xxx.90 eq ftp
access-list outside_in permit tcp any host xxx.xxx.xxx.90 eq 9999
access-list outside_in permit tcp any host xxx.xxx.xxx.93 eq 3389
access-list outside_in permit tcp any host xxx.xxx.xxx.90 eq www
access-list outside_in permit tcp any host xxx.xxx.xxx.90 eq 1433
access-list outside_in permit tcp any host xxx.xxx.xxx.90 eq 1434
access-list outside_in permit tcp any host xxx.xxx.xxx.90 eq 2433
access-list outside_in permit tcp any host xxx.xxx.xxx.90 eq 2344
access-list outside_in permit tcp any host xxx.xxx.xxx.86 eq www
access-list outside_in permit tcp any host xxx.xxx.xxx.94 eq www
access-list outside_in permit tcp any host xxx.xxx.xxx.94 eq 3306
access-list outside_in permit tcp any host xxx.xxx.xxx.94 eq 8080
access-list outside_in permit tcp any host xxx.xxx.xxx.94 eq ssh
access-list DMZ1_in permit icmp any any echo-reply
access-list DMZ1_in permit icmp any any unreachable
access-list DMZ1_in permit icmp any any time-exceeded
access-list DMZ1_in permit udp any any eq domain
access-list DMZ1_in permit tcp 192.168.10.0 255.255.255.0 any eq 1433
access-list DMZ1_in permit tcp 192.168.10.0 255.255.255.0 any eq 1434
access-list DMZ1_in permit tcp 192.168.10.0 255.255.255.0 any eq 2433
access-list DMZ1_in deny ip any 192.168.1.0 255.255.255.0
access-list DMZ1_in permit ip any any
pager lines 24
mtu outside 1500
mtu inside 1500
mtu DMZ1 1500
mtu intf3 1500
mtu intf4 1500
mtu intf5 1500
ip address outside xxx.xxx.xxx.87 255.255.255.240
ip address inside 192.168.1.1 255.255.255.0
ip address DMZ1 192.168.10.1 255.255.255.0
no ip address intf3
no ip address intf4
no ip address intf5
ip audit info action alarm
ip audit attack action alarm
no failover
failover timeout 0:00:00
failover poll 15
no failover ip address outside
no failover ip address inside
no failover ip address DMZ1
no failover ip address intf3
no failover ip address intf4
no failover ip address intf5
pdm location 192.168.1.167 255.255.255.255 inside
pdm location 192.168.1.249 255.255.255.255 inside
pdm location 192.168.1.0 255.255.255.0 DMZ1
pdm location 192.168.10.50 255.255.255.255 DMZ1
pdm location 192.168.10.54 255.255.255.255 DMZ1
pdm location 192.168.10.51 255.255.255.255 DMZ1
pdm location 192.168.10.53 255.255.255.255 DMZ1
pdm location 192.168.1.10 255.255.255.255 inside
pdm location 192.168.1.3 255.255.255.255 inside
pdm location 192.168.10.2 255.255.255.255 DMZ1
pdm location 192.168.1.88 255.255.255.255 inside
pdm location 192.168.1.181 255.255.255.255 inside
pdm history enable
arp timeout 14400
global (outside) 10 xxx.xxx.xxx.82
nat (inside) 10 0.0.0.0 0.0.0.0 0 0
static (inside,outside) xxx.xxx.xxx.83 192.168.1.249 dns netmask 255.255.255.255 0 0
static (DMZ1,outside) xxx.xxx.xxx.90 192.168.10.50 dns netmask 255.255.255.255 0 0
static (DMZ1,outside) xxx.xxx.xxx.92 192.168.10.51 dns netmask 255.255.255.255 0 0
static (DMZ1,outside) xxx.xxx.xxx.86 192.168.10.53 dns netmask 255.255.255.255 0 0
static (inside,DMZ1) 192.168.1.0 192.168.1.0 dns netmask 255.255.255.0 0 0
static (inside,outside) xxx.xxx.xxx.94 192.168.1.10 netmask 255.255.255.255 0 0
static (inside,outside) xxx.xxx.xxx.93 192.168.1.181 netmask 255.255.255.255 0 0
access-group outside_in in interface outside
access-group DMZ1_in in interface DMZ1
rip inside default version 2
route outside 0.0.0.0 0.0.0.0 xxx.xxx.xxx.81 1
timeout xlate 3:00:00
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 TACACS+ max-failed-attempts 3
aaa-server TACACS+ deadtime 10
aaa-server RADIUS protocol radius
aaa-server RADIUS max-failed-attempts 3
aaa-server RADIUS deadtime 10
aaa-server LOCAL protocol local
http server enable
http 192.168.1.167 255.255.255.255 inside
no snmp-server location
no snmp-server contact
snmp-server community public
no snmp-server enable traps
tftp-server inside 192.168.1.252 /
floodguard enable
telnet timeout 5
ssh 192.168.1.167 255.255.255.255 inside
ssh timeout 60
console timeout 0
terminal width 80
Cryptochecksum
: end


Any ideas?  Is my DMZ1_in access-list wrong?
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Question by:MBIstephen
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5 Comments
 
LVL 79

Expert Comment

by:lrmoore
ID: 13981293
Are you getting any hits on this access-list entry (show access-list)
>access-list DMZ1_in permit udp any any eq domain

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Author Comment

by:MBIstephen
ID: 13984017
Yep, actually the issue was, there were multiple IP adresses assigned to the NIC on the windows box, and an ipconfig/all revealed that it was listening on an address that was not on the same network as the DMZ.

So this begs the question, how do I support two different external addresses pointing to two different internal addresses on the same NIC (windows 2000 and 2003)?

Can I use nat to do this?  Obviously a static won't work, since static is 1 to 1.  They want to run multiple web sites per NIC using multiple addresses, with multiple external addresses pointing to multiple internal address....

Can the PIX even do this?
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LVL 79

Accepted Solution

by:
lrmoore earned 2000 total points
ID: 13985358
The answer is - yes. You can use port forwarding
  static (inside,outside) tcp <publicip1> port <privateip1> port netmask 255.255.255.255

ie. Same server has multiple IPs bound to NIC
 static (inside,outside) tcp 1.2.3.4 80 192.168.1.4 80 netmask 255.255.255.255
 static (inside,outside) tcp 1.2.3.5 80 192.168.1.5 80 netmask 255.255.255.255
 static (inside,outside) tcp 1.2.3.6 80 192.168.1.6 80 netmask 255.255.255.255
Now, I can still use 1.2.3.4 to re-direct email to yet a different server
  static (inside,outside) tcp 1.2.3.4 25 192.168.1.57 25 netmask 255.255.255.255

You can use the same outside IP and forward different ports to different inside hosts
You can forward multiple ports from different public ips to the same inside host
   static (inside,outside) tcp 1.2.3.5 80 192.168.1.5 80 netmask 255.255.255.255
   static (inside,outside) tcp 1.2.3.6 110 192.168.1.5 110 netmask 255.255.255.255

What you CANNOT do is forward the same outside IP+port to multiple inside hosts
You CANNOT forward multiple outside IP/ports to the same inside host/port
0
 

Author Comment

by:MBIstephen
ID: 13987556
Excellent!  Thank you so much!

This place rocks!
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LVL 79

Expert Comment

by:lrmoore
ID: 13987992
Glad to help!
- Cheers!

<8-}
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