stateful packet inspection -- relation to clients' computer security

Posted on 2009-07-02
Medium Priority
Last Modified: 2012-05-07
What does the "state" of a TCP/IP packet have to do with whether it is from a user-requested web site, or from a hacker trying to gain access to a client computer, with reagrd to the "stateful packet inspection" that presumably only hardware firewalls are capable of?
Question by:Casey Claassen
LVL 32

Accepted Solution

rsivanandan earned 140 total points
ID: 24765085
To simply look at it,

If the packet coming from outside

1. Has SYN and ACK bit set then it means that the connection was indeed originated from the inside machine and that is why acknowledgment is coming.

2. After that every packet passed has sequence numbers which are math bound and has relation with the packet sent.

So keeping the state information helps find it.

Now if a hacker sends a reply packet with 'syn' and 'ack' bit set, the machine won't entertain it since it didn't originate that traffic at all.

Does that help?


Author Closing Comment

by:Casey Claassen
ID: 31599172
Yes, that does indeed help!

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