pix static command

Answered Question

Hi


When use static command map subnet, like, static (inside,dmz) 192.168.0.0 192.168.0.0 netmask 255.255.255.0, does have security issue with it? What is infected for security if disable NAT with static command?


Thanks


ben

Correct Answer by zubairjalal about 10 years 5 days ago

Doing a no nat also creates a translation slot in the xlate table. For eg. consider the statement


Static (inside,outside) 10.10.10.1 10.10.10.1 netmask 255.255.255.255


The above statement will still have a translation slot and will undergo the NAT process which is required as per the PIX ASAlgoritim. The 10.10.10.1 if going from inside to outside will go AS IT IS.


sh xlate local 10.10.10.1 will show you something like this


local 10.10.10.1 Global 10.10.10.1

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Patrick Iseli Sat, 04/21/2007 - 16:16
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This command basicly in your example just disables the Adress Translation and communicate for all traffic from the inside to the DMZ network with its private IP's.


In security perspective this does not change anything. You still need to configure an Access-list to allow the traffic flow.


The is a little exception with the 6.3 code with usually allow all traffic flow from the higher security level to all lower security levels. And of course if there is not NAT or PAT then there would not be any traffic flow.

So in this partiular case you need to setup access-lists to secure the networks.


sincerely

Patrick

Thanks. One more question:

Firewall default design not to allow all traffic flow from the lower security level to all higher security levels, does it depends on NAT setup? If disable NAT, does firewall will allow traffic flow from the lower security level to higher security level which depends access-list permit setup?


ben

zubairjalal Mon, 04/23/2007 - 03:11
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Hi.


PIX will not forward any traffic which does not have the corresponding translation entry. Unless and until the transaltion slot has not been created for the traffic, pix will not allow it to pass through.



Correct Answer
zubairjalal Mon, 04/23/2007 - 09:44
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Doing a no nat also creates a translation slot in the xlate table. For eg. consider the statement


Static (inside,outside) 10.10.10.1 10.10.10.1 netmask 255.255.255.255


The above statement will still have a translation slot and will undergo the NAT process which is required as per the PIX ASAlgoritim. The 10.10.10.1 if going from inside to outside will go AS IT IS.


sh xlate local 10.10.10.1 will show you something like this


local 10.10.10.1 Global 10.10.10.1

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