Solved

DMZ to Inside connection

Posted on 2008-10-01
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Last Modified: 2008-10-13
I have a new ASA 5505 firewall with Security Plus license that is configured with 3 interfaces--outside, inside and dmz. I can configure it to allow outside connections to the DMZ, inside and DMZ connections to the outside and inside connections to the DMZ.  I still need to allow connections from the DMZ to the inside so that a client or web server located in the DMZ can contact another web server on the inside network.  I have looked at all the documentation, knowledge base articles, etc, and am still coming up dry.  

Here is a summary of the interface IP assignments:
outside: single public address
inside network: 192.168.1.0 255.255.255.0; inside server: 192.168.1.25
dmz network: 192.168.2.0 255.255.255.0; dmz-web-server: 192.168.2.10

Although the outside is set to obtain an IP address from a DHCP server, this is a lab environment and any changes are monitored and incorporated.  Also, the inside and dmz web servers are set statically.

Can someone please help? I have read similar problems on this forum, but have been unsuccessful in getting them to work.
Thank you.
ASA Version 7.2(4)

!

hostname asaEast

domain-name mydomain.com

enable password oNRzEHTKYcYWDvTv encrypted

passwd 2KFQnbNIdI.2KYOU encrypted

names

name 192.168.2.10 dmz-web-server

name 192.168.1.25 inside-server

name xxx.xxx.xxx.131 outside

!

interface Vlan1

 nameif inside

 security-level 100

 ip address 192.168.1.1 255.255.255.0

!

interface Vlan2

 nameif outside

 security-level 0

 ip address dhcp setroute

!

interface Vlan3

 nameif dmz

 security-level 50

 ip address 192.168.2.1 255.255.255.0

!

interface Ethernet0/0

 switchport access vlan 2

!

interface Ethernet0/1

!

interface Ethernet0/2

 switchport access vlan 3

!

interface Ethernet0/3

!

interface Ethernet0/4

!

interface Ethernet0/5

!

interface Ethernet0/6

!

interface Ethernet0/7

!

ftp mode passive

dns server-group DefaultDNS

 domain-name mydomain.com

same-security-traffic permit inter-interface

access-list outside_access_in extended permit tcp any host outside eq www

access-list dmz_access_in extended permit tcp host dmz-web-server host 192.168.2.25 eq www

access-list dmz_access_in extended permit icmp host dmz-web-server host 192.168.2.25

pager lines 24

logging enable

logging asdm informational

mtu inside 1500

mtu outside 1500

mtu dmz 1500

no failover

icmp unreachable rate-limit 1 burst-size 1

asdm image disk0:/asdm-524.bin

no asdm history enable

arp timeout 14400

global (outside) 1 interface

global (inside) 1 192.168.1.75-192.168.1.100 netmask 255.255.255.0

global (dmz) 1 192.168.2.50-192.168.2.75 netmask 255.255.255.0

nat (inside) 1 192.168.1.0 255.255.255.0

nat (dmz) 1 192.168.2.0 255.255.255.0

static (dmz,outside) tcp interface www dmz-web-server www netmask 255.255.255.255

static (inside,dmz) 192.168.2.25 inside-server netmask 255.255.255.255

access-group outside_access_in in interface outside

route outside 0.0.0.0 0.0.0.0 129.130.27.240 1

timeout xlate 3:00:00

timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 icmp 0:00:02

timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00 mgcp-pat 0:05:00

timeout sip 0:30:00 sip_media 0:02:00 sip-invite 0:03:00 sip-disconnect 0:02:00

timeout sip-provisional-media 0:02:00 uauth 0:05:00 absolute

http server enable

http 192.168.1.0 255.255.255.0 inside

no snmp-server location

no snmp-server contact

snmp-server enable traps snmp authentication linkup linkdown coldstart

telnet 192.168.2.0 255.255.255.0 inside

telnet timeout 5

ssh timeout 5

console timeout 0

dhcpd auto_config outside

!

dhcpd address inside-server-192.168.1.50 inside

dhcpd dns 129.130.254.2 129.130.254.3 interface inside

dhcpd enable inside

!

dhcpd address dmz-web-server-192.168.2.20 dmz

dhcpd dns 129.130.254.2 129.130.254.3 interface dmz

dhcpd enable dmz

!

 

!

!

prompt hostname context

Cryptochecksum:513f12e2d588cd9f4391b3979b759ef0

: end

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0
Comment
Question by:InOz
  • 5
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13 Comments
 
LVL 13

Expert Comment

by:Quori
ID: 22618785
You would need to add an ACL (Inside_access_in) and permit specific traffic there.
0
 
LVL 33

Expert Comment

by:MikeKane
ID: 22618786
You haven't applied the access group for the dmz interface

access-group dmz_access_in in interface dmz

0
 

Author Comment

by:InOz
ID: 22619072
To MikeKane-- you're right, I did forget to bind the access-list to the interface, but after I did that, still no joy.

To Quori-- I wonder why the access-list (dmz_access_in) is not accomplishing this. If I need to add another access list entry (inside_access_in), what would it look like?  Currently it allows access from the dmz web server to the inside server by translating its dmz address (192.168.2.10 to  192.168.2.25).  I did change the translated address to 192.168.1.20, but no joy here either.
0
 
LVL 13

Expert Comment

by:Quori
ID: 22619090
dmz_access_in is for traffic going into the interface. With the way ASA security levels work, DMZ traffic is implicitly being denied access to a higher security level (50 to 100).

So, you use inside_access_in to allow INBOUND traffic from the DMZ into internal.
0
 
LVL 13

Expert Comment

by:Quori
ID: 22619112
At least, thats how I got my ASA to play ball. It is entirely possible I boned something and don't realise it ;)
0
 
LVL 33

Expert Comment

by:MikeKane
ID: 22619207
That's not correct.   Inside access in in int inside would be used for connections originating from the inside and the ACL would allow or deny them to the interface.  


I have a feeling one of your nat's or statics might be to blame.  

run a SHOW XLATE and see what addresses are being handed out.  

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Author Comment

by:InOz
ID: 22619320
Show xlate returns:

3 in use, 73 most used
Global 192.168.2.25 Local inside-server
PAT Global outside(80) Local dmz-web-server(80)
Global 192.168.2.51 Local inside-server
 
0
 
LVL 33

Expert Comment

by:MikeKane
ID: 22664043
Global 192.168.2.25 Local inside-server
Global 192.168.2.51 Local inside-server

Your inside server is grabbing the static and a NAT'd address to the DMZ.  

You also have not assigned your Inside VLAN to an interface....  

You need to Add that access-group to the DMZ in interface command.  

POst the new code after these are complete.  

In your ASA's syslog, you can see packets being dropped and if it is because of an ACL, this will tell you which is to blame.    

0
 

Author Comment

by:InOz
ID: 22664706
Attached is the new configuration file.  The inside vlan is assigned to all interfaces by default when you use the Startup Wizard in the ASDM.  Just to be sure, I ran a switchport access command to assign interface Ethernet0/0 to the inside.  Afterwards, the conf file remained as it was, so I think that part is okay.  Anyway--now I have access from the inside to the dmz, from the dmz to the inside, but no access from the outside to the dmz nor from the dmz to the outside.  The syslog tells me that the dmz_access_in access-list is the culprit.  
ASA Version 7.2(4) 

!

hostname asaEast

domain-name netlab.ksu.edu

enable password oNRzEHTKYcYWDvTv encrypted

passwd 2KFQnbNIdI.2KYOU encrypted

names

name 192.168.2.10 dmz-web-server

name 192.168.1.25 inside-server

name xxx.xxx.xx.131 outside

!

interface Vlan1

 nameif inside

 security-level 100

 ip address 192.168.1.1 255.255.255.0 

!

interface Vlan2

 nameif outside

 security-level 0

 ip address dhcp setroute 

!

interface Vlan3

 nameif dmz

 security-level 50

 ip address 192.168.2.1 255.255.255.0 

!

interface Ethernet0/0

 switchport access vlan 2

!

interface Ethernet0/1

!

interface Ethernet0/2

 switchport access vlan 3

!

interface Ethernet0/3

!

interface Ethernet0/4

!

interface Ethernet0/5

!

interface Ethernet0/6

!

interface Ethernet0/7

!

ftp mode passive

dns server-group DefaultDNS

 domain-name netlab.ksu.edu

same-security-traffic permit inter-interface

access-list outside_access_in extended permit tcp any host outside eq www 

access-list dmz_access_in extended permit tcp host dmz-web-server host 192.168.2.25 eq www 

access-list dmz_access_in extended permit icmp host dmz-web-server host 192.168.2.25 

pager lines 24

logging enable

logging asdm informational

mtu outside 1500

mtu inside 1500

mtu dmz 1500

no failover

monitor-interface outside

monitor-interface inside

monitor-interface dmz

icmp unreachable rate-limit 1 burst-size 1

asdm image disk0:/asdm-524.bin

no asdm history enable

arp timeout 14400

global (outside) 1 interface

global (inside) 1 192.168.1.75-192.168.1.100 netmask 255.255.255.0

global (dmz) 1 192.168.2.50-192.168.2.75 netmask 255.255.255.0

nat (inside) 1 192.168.1.0 255.255.255.0

nat (dmz) 1 192.168.2.0 255.255.255.0

static (dmz,outside) tcp interface www dmz-web-server www netmask 255.255.255.255 

static (inside,dmz) 192.168.2.25 inside-server netmask 255.255.255.255 

access-group outside_access_in in interface outside

access-group dmz_access_in in interface dmz

route outside 0.0.0.0 0.0.0.0 129.130.27.240 1

timeout xlate 3:00:00

timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 icmp 0:00:02

timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00 mgcp-pat 0:05:00

timeout sip 0:30:00 sip_media 0:02:00 sip-invite 0:03:00 sip-disconnect 0:02:00

timeout sip-provisional-media 0:02:00 uauth 0:05:00 absolute

http server enable

http 192.168.1.0 255.255.255.0 inside

no snmp-server location

no snmp-server contact

snmp-server enable traps snmp authentication linkup linkdown coldstart

telnet 192.168.1.0 255.255.255.0 inside

telnet timeout 60

ssh timeout 5

console timeout 0

dhcpd auto_config outside

!

dhcpd address inside-server-192.168.1.50 inside

dhcpd dns xxx.xxx.xxx.2 xxx.xxx.xxx.3 interface inside

dhcpd enable inside

!

dhcpd address dmz-web-server-192.168.2.20 dmz

dhcpd dns xxx.xxx.xxx.2 xxx.xxx.xxx.3 interface dmz

dhcpd enable dmz

!
 

!

class-map inspection_default

 match default-inspection-traffic

!

!

policy-map type inspect dns preset_dns_map

 parameters

  message-length maximum 512

policy-map global_policy

 class inspection_default

  inspect dns preset_dns_map 

  inspect ftp 

  inspect h323 h225 

  inspect h323 ras 

  inspect rsh 

  inspect rtsp 

  inspect esmtp 

  inspect sqlnet 

  inspect skinny 

  inspect sunrpc 

  inspect xdmcp 

  inspect sip 

  inspect netbios 

  inspect tftp 

!

service-policy global_policy global

prompt hostname context 

Cryptochecksum:548ad1dda89517ad98628f7136eac217

: end

asdm image disk0:/asdm-524.bin

asdm location dmz-web-server 255.255.255.255 inside

no asdm history enable

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LVL 33

Assisted Solution

by:MikeKane
MikeKane earned 250 total points
ID: 22664723
I don't think you can use
global (outside) 1 interface
and
static (dmz,outside) tcp interface www dmz-web-server www netmask 255.255.255.255
At the same time.....   I'll have to read up on that to be sure, unless another expert wants to jump in there.  

If I'm right, you'll just have to use a port forward command instead of the 1 to 1 static.  

Standby......
0
 

Author Comment

by:InOz
ID: 22664771
Tell me how to set up a port forward command
0
 
LVL 33

Assisted Solution

by:MikeKane
MikeKane earned 250 total points
ID: 22668612
Port forwarding for your scenario is as follows:

static (dmz,outside) tcp interface www dmz-web-server www


On the other issue I was looking at, I know for certain that you can't create 2 statics to the same internal address, I'm still looking for the documentation or proof on using the global interface with a static of the same ip.....
0
 

Accepted Solution

by:
InOz earned 0 total points
ID: 22669851
See below for the new set of access rules and statics.  It now works.

access-list outside_access_in extended permit tcp any host outside eq www

! the next line uses a new public IP address for the dmz server

access-list outside_access_in extended permit tcp any host xxx.xxx.xxx.43 eq www 

access-list acl_dmz extended permit ip 192.168.2.0 255.255.255.0 any

access-list dmz_access_in extended permit tcp host dmz-web-server host 192.168.2.25 eq www

access-list dmz_access_in extended permit icmp host dmz-web-server host 192.168.2.25

global (outside) 1 interface

global (inside) 1 192.168.1.75-192.168.1.100 netmask 255.255.255.0

! set up PAT for dmz on outside interface

global (dmz) 3 interface

nat (inside) 1 192.168.1.0 255.255.255.0

nat (dmz) 1 192.168.2.0 255.255.255.0

static (dmz,outside) tcp xxx.xxx.xxx.43 www dmz-web-server www netmask 255.255.255.255

static (inside,dmz) 192.168.2.25 inside-server netmask 255.255.255.255

access-group outside_access_in in interface outside

access-group acl_dmz in interface dmz

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