North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: key change for TCP-MD5

  • From: Randy Bush
  • Date: Wed Jun 21 10:34:12 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