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TOPIC: Problem with DMZ nat?

Problem with DMZ nat? 9 years 4 months ago #22568

  • skepticals
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I am trying to allow SMTP traffic from a host in my DMZ to a host on the Inside interface. I used the packet trace and it appears the ACL is correct, but the NAT isn't?

Interfaces:
[code:1]!
interface Ethernet0/0
description WAN Interface
nameif outside
security-level 0
ip address 198.x.x.x 255.255.255.240
!
interface Ethernet0/1
description DMZ Interface
nameif DMZ
security-level 50
ip address 172.16.0.1 255.255.255.0
!
interface Ethernet0/2
description Lan Interface
nameif inside
security-level 100
ip address 10.3.254.1 255.255.255.0
![/code:1]

Access lists:[code:1]access-list Static extended permit icmp any any echo-reply
access-list Static extended permit icmp any any unreachable
access-list CPL_splitTunnelAcl standard permit 10.3.254.0 255.255.255.0
access-list inside_nat0_outbound extended permit ip 10.3.254.0 255.255.255.0 10.3.254.0 255.255.255.192
access-list inside_nat0_outbound extended permit ip 10.3.4.0 255.255.255.0 10.3.254.0 255.255.255.192
access-list inside_nat0_outbound extended permit ip 192.168.0.0 255.255.0.0 10.3.4.0 255.255.255.0
access-list DMZ_to_Inside extended permit tcp host 172.16.0.5 host 10.3.4.50 eq smtp [/code:1]

Global NAT:[code:1]global (outside) 1 interface
nat (inside) 0 access-list inside_nat0_outbound
nat (inside) 1 10.3.0.0 255.255.0.0[/code:1]

Static commands:[code:1]static (inside,outside) 198.x.x.x 10.3.5.5 netmask 255.255.255.255
static (inside,outside) 198.x.x.x 10.3.5.4 netmask 255.255.255.255
static (inside,outside) 198.x.x.x 10.3.5.6 netmask 255.255.255.255
static (inside,outside) 198.x.x.x 10.3.6.10 netmask 255.255.255.255
static (inside,outside) 198.x.x.x 10.3.4.10 netmask 255.255.255.255
static (inside,outside) 198.x.x.x 10.3.4.13 netmask 255.255.255.255
static (DMZ,outside) 198.x.x.x 172.16.0.3 netmask 255.255.255.255
static (inside,outside) 198.x.x.x 10.3.3.7 netmask 255.255.255.255
static (DMZ,outside) 198.x.x.61 172.16.0.5 netmask 255.255.255.255
static (inside,DMZ) 10.3.3.0 10.3.3.0 netmask 255.255.255.0 [/code:1]

Access groups: [code:1]access-group Static in interface outside
access-group DMZ_to_Inside in interface DMZ[/code:1]

I need to allow DMZ host: 172.16.0.5 to send SMTP to Inside host 10.3.4.50.

What is this doing?
access-list inside_nat0_outbound and nat (inside) 0 access-list inside_nat0_outbound

Thanks.
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Re: Problem with DMZ nat? 9 years 4 months ago #22578

  • ramasamy
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Hi,

The NAT is there only for the traffic which is going to outside network and not to the DMZ network from Inside LAN.

Give the below mentioned commands and check.

global (DMZ) 1 interface
nat (inside) 1 10.3.0.0 255.255.0.0

:)
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Re: Problem with DMZ nat? 9 years 4 months ago #22582

  • skepticals
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Thank you for the reply.

Should I have to use:
[code:1]
global (DMZ) 2 interface
nat (inside) 2 10.3.0.0 255.255.0.0
[/code:1]
Instead of: [code:1]
global (DMZ) 1 interface
nat (inside) 1 10.3.0.0 255.255.0.0
[/code:1]

I already have a set numbered 1 for traffic outside of the outside interface. Do those numbers have to be unique to each set?

Also, I have a static command that allows traffic from the inside network to the DMZ. Do I need the global command also?
[code:1]
static (inside,DMZ) 10.3.3.0 10.3.3.0 netmask 255.255.255.0
[/code:1]
I thought this code was translating the 10.3.3.0 network to 10.3.3.0 on the DMZ. Is this incorrect?
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Re: Problem with DMZ nat? 9 years 4 months ago #22585

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After researching more and testing other configs it came to me that I only have a static command for the 10.3.3.0 subnet and not the subnet that my servers are in. I added a new static translation for that network and everything works. This is without the added global/nat command you asked me to use.
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