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CBAC question - Cisco IOS firewall

Posted on 2011-03-07
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A quick question, as I am little confused... CBAC:

ip inspect name firewall tcp
ip inspect name firewall udp
ip inspect name firewall tftp
ip inspect name firewall smtp
...

What is the point in listing ALL these protocols, if we put tcp and udp at the top of the list? I assume that if I put 'inspect tcp', it will include ftp, smtp etc... ???
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Question by:m1979
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harbor235 earned 250 total points
ID: 35070012

Generically you can look at TCP or UDP, layer 4, or you can look deeper into the packet via layer 7.
So, additional deep packet inspection capabilities.  So for example, inspection of mail would allow you much more granularity inspecting the commands the mail application uses, allowing or disallowing specific mail commands or security threats  

harbor235 ;}
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by:asavener
asavener earned 250 total points
ID: 35070027
TCP inspection simply allows the router to watch simple TCP sessions and allow the traffic back through the firewall.

For more complex protocols (such as FTP which uses secondary connectoins), or to make sure that traffic on a particular port conforms to the protocol standard (such as making sure that traffic on port 25 is SMTP), you will need to use the proper keywords.
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by:m1979
ID: 35070391
Thx
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