[Snort-users] tcp flood

Matt Kettler mkettler at ...4108...
Mon Mar 7 14:13:38 EST 2005

At 03:25 PM 3/7/2005, SN ORT wrote:
>You can rate-limit on just about any Cisco device
>(including PiX) to limit DoS attacks, including TCP
>SYN attacks, by using access-lists with rate-limit
>commands. Look to your Internet routers to stop the


The Cisco PiX OS as of the most recent released version 6.3(4) does not 
support rate-limit in an access-list.


The rate-limit feature requires QoS support, something the PiX currently 
lacks entirely, but the as-yet-unreleased PiX OS 7.0 is reported (by 
Cisco's website) to support QoS.

The "new features" datasheet for PiX 7.0 is listed here:


Any QoS enabled IOS image should be able to do rate limiting, but I'm not 
sure which IOS feature sets have QoS and which do not.

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