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ASA-Inspection Rules

Hi,

What is the basic purpose of Inspection rules,how the rules works and what will happen if we remove the rule

Regaards
ramu
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RAMU CH
Asked:
RAMU CH
3 Solutions
 
jmeggersSr. Network and Security EngineerCommented:
At basic, rules permit traffic from more secure interfaces (such as outside) to more secure interfaces.  You can apply rules anywhere, but they are absolutely needed in this way.  They allow granular control over what ports, protocols, source, addresses, destination addresses, etc. are allowed in from the less trusted side.
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Ernie BeekExpertCommented:
Nope. Inspection rules enforce the stateful inspection of several (commonly used) protocols.
For example, if you enable stateful inspection for ftp, the ASA knows that when a connection comes in on port 21 (ftp) there can also be traffic on port 20 (ftp-data) from that same source.

Or as Cisco says:
Inspection rules configure protocol inspection on a device. Inspection opens temporary holes in your access rules to allow return traffic for connections initiated within your trusted network. When traffic is inspected, the device also implements additional controls to eliminate mal-formed packets based on the inspected protocols.

Source: http://www.cisco.com/en/US/docs/security/security_management/cisco_security_manager/security_manager/4.1/user/guide/fwinsp.html
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Ernie BeekExpertCommented:
Oh, and reading the previous, you might imagine what happens if you remove them.

No worries though ;)  I've had issues where some rules had to be removed to make thing function properly.
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Feroz AhmedSenior Network EngineerCommented:
Hi,

Each Inpsection Rule has meaning and each rule defines a rule .for example if Inspect ICMP is not removed then one cannot ping from Inside Interface to outside Interface.If the same rule is implemented then one can ping from Inside Network to Outside network.likewise each inspection rule defines each rule .
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RAMU CHAuthor Commented:
Thanks
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