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Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Syn attacks

Is there a possible other way beside CSS switches and rate-limits on the router to prevent Syn floods on our internet uplinks/Transits?

A Pix is not in the picture yet:)


Re: Syn attacks

The focus of this board is Virtual Private Networks, however, there are a number of professionals online who may be able to assist you.

If you don't get a suitable response to your post, you may wish to reveiw this document on

If anyone else in the forum has some pointers, please reply to this thread.

Thank you for posting.

New Member

Re: Syn attacks

An ACL on your head-in routers? We use CSIDS (Netranger) to detect and apply ACLs dynamically. Its good for syn floods and such, not so good for more complex stuff, Unicode, etc., we have to depend on Cisco for the signatures, ...but then again, there is no perfect IDS.

New Member

Re: Syn attacks

We've implemented the NetRanger, but had some difficulty with ACL updates, i.e. the Device Management Module. I would really be interested in how you find the ACL updates working for you?

What is your experience with the Netranger signature update frequency and completeness?

Thanks for any info.

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