key change for TCP-MD5

Randy Bush randy at psg.com
Wed Jun 21 14:32:16 UTC 2006


>>>> The added cost for CPU-bound systems is that they have to try
>>>> (potentially) multiple keys before getting the **right** key
>>>> but in real life this can be easily mitigated by having a rating
>>>> system on the key based on the frequency of success.
>>> This mitigates the effect of authenticating valid packets. However,
>>> this does not appear to help at all in terms of minimizing the DOS
>>> effect of an intentional DoS attack that uses authenticated packets
>>> (with the processing time required to check the keys the intended
>>> damage of the attack).
>> gstm
> this doesn't help if the vendor can't implement it
> correctly and does the md5 calc before checking the ttl :(

hard to imagine anything that will help such a vendor

randy




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