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1st DMZ - Setup

Posted on 2004-10-07
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Last Modified: 2010-04-09
Hi,

We've recently purchased a new firewall (Sonicwall) and I'm looking at setting up a DMZ for the 1st time.  

Now if I put a couple of servers into the DMZ,  I need the servers to be able to talk to our main database (non SQL) back on the protected LAN.  What are my configuration considerations on the firewall ?  The part I'm unsure on is what ports would I need to open from the LAN to DMZ and DMZ to LAN, so these servers can talk to the protected network ?

Thanks again
Steve

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Question by:stevendunne
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6 Comments
 

Expert Comment

by:rolltide_bama
ID: 12249299
not sure on how the sonic treats access going from more secure to less secure but on a pix access to lower security is allowed ususally through a global statement and a nat command.  you will need an access-list and specify the sql ports. Microsoft sql ports 1433 and 1434, Oracle is 1521. Well l hope this gets you in the right direction.
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Expert Comment

by:gary_b
ID: 12250911
Hi Steve,
I am in the middle of a similair task so here my 10 pence worth...if it helps.
Firstly what SW are you using & what SW OS. I use a TZ170 enhanced OS as follows:

By default, the SonicWALL allows all traffic from the WAN to access the DMZ, but prevents WAN traffic from accessing the protected LAN segment. All LAN traffic can pass outward to the DMZ or the WAN, but only traffic originating in the DMZ or traffic that is part of a session that a LAN user initiated can enter the LAN. You could however create a policy/rule to allow traffic from the DMZ through your chosen port (SQL 1433 and 1434) to an address group inside the LAN segment (ie SQL server etc), which should I believe solve your problem.

Hope this helps
G
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Author Comment

by:stevendunne
ID: 12257566
Hi Gary,

Thanks for the Info.  We are using the same FW, but the StandardOS.

I was thinking of creating the following rules:

1) LAN > DMZ - Any - Allow    

Although I'm told this should be restricted to the ports you only need to use.  Is this true ?

2) WAN > DMZ - Any - Deny

3) WAN > DMZ - 80, 443, 21 - Allow

4) DMZ > LAN - 1433, 1434 - Allow


What about ports 135, 139, 445, do these need to be open to enable communication between the LAN & DMZ ?

Thanks
Steve

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Expert Comment

by:gary_b
ID: 12257690
Hi Steve,

>>1) LAN > DMZ - Any - Allow  
Spot on!

>>Although I'm told this should be restricted to the ports you only need to use.  Is this true ?
You could I guess open only ports 80, 443, 21 + DB port, but I trust the LAN > DMZ link in my scenario so have LAN > DMZ - Any - Allow.

2) WAN > DMZ - Any - Deny
3) WAN > DMZ - 80, 443, 21 - Allow
Spot on! If you know where your visitors are coming from you could lock it down even futher:

4) DMZ > LAN - 1433, 1434 - Allow
I have no rules to allow/block traffic...
(I think thats an Enhanced OS feature, so you better use your rules above in standardOS)

>>What about ports 135, 139, 445, do these need to be open to enable communication between >>the LAN & DMZ ?
As in step 1 above LAN > DMZ - Any - Allow
or in your case LAN > DMZ - 80, 443, 21 + DB port - Allow
This one depends on how well you trust your LAN..

Hope this is of some help but please ask againif not....
G

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Author Comment

by:stevendunne
ID: 12257771
1) How do you mean "Trust" your LAN ?

2) LAN > DMZ - 80, 443, 21 + Database port - Allow

Where does this leave ports 135, 139 & 445 for communication ?  Or are these not essential ?

3) DMZ > LAN - 1433, 1434 - Allow

If I don't setup the above rule, how will the server in the DMZ communicate with the LAN when traffic originates (starts off) in the DMZ ?

Thanks again

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Accepted Solution

by:
gary_b earned 375 total points
ID: 12258185
Hi Steve,

>>1) How do you mean "Trust" your LAN ?
Nothing special, just saying that I allow all traffic between LAN > DMZ becuase I know where the traffic is originating, as opposed to the WAN which I do not trust, because I do not know where traffic is originating....

>>2) LAN > DMZ - 80, 443, 21 + Database port - Allow
>>Where does this leave ports 135, 139 & 445 for communication ?  Or are these not essential ?
Again if you LAN > DMZ - All - Allow, you should not encounter any problems here.

>>3) DMZ > LAN - 1433, 1434 - Allow
>>If I don't setup the above rule, how will the server in the DMZ communicate with the LAN when >>traffic originates (starts off) in the DMZ ?
I admit to not knowing how your SQL/IIS operates but surely all traffic originates in the LAN via broswer requests? If not then I believe you will indeed need to open the ports as you rightly stated.

Cheers
G
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