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New Member

TCP Reset Feature


I would like to realize the reset of a single TCP connection (Ip adress + port number) using a

CISCO IDS 4235,Version 4.1(5)S194, with a

PIX 520, IOS Version 6.3(3) and a

4500 router, IOS Version 12.0(8b).

Is it really possible by this hardware?

I think I need at least ROUTER IOS version 12.2(15), but I cannot do this upgrade on my device. Is it true?

Is the PIX able of resetting the single connection? Maybe IOS Ver 7.00 needed?

It's possible to upgrade PIX 520 ?

Thank you in advance!

New Member

Re: TCP Reset Feature

TCP reset feature on the IDS by default will send out a TCP reset through the sniffing interface.

However, it sounds like you are talking about shun connection rather than tcp reset. A shun will effectively block the connection by applying a filter (rather than a packet to terminate the connection), it does this by applying this filter on your router or PIX.

On the PIX this is achieved through a filter function called a shun command. This is actually available on the version of PIX you are running (6.3.x)

On the Router an ACL is applied on an interface.

I hope that helps.


New Member

Re: TCP Reset Feature

Thank you very much for your interest!

No,I'm really talking about TCP Reset feature. This is the situation: I would like to reset a P2P connection without blocking the IP since it could represent a NAT address.

I cannot obtain the RESET, probably because of my router IOS Version 12.0 ?

I'm quite sure it is not possible to reset the connection by PIX, is it true?



New Member

Re: TCP Reset Feature


The resets are done by the sensor, not the PIX.

To get your reset to work, your P2P connection would have to (1)be seen by the sensing interface, (2)trigger an alarm, and (3)the matching signature would need its TCP Reset Action enabled. No IP addresses would be blocked.