Blocking Win95 hosts [WAS: Lazy network operators - NOT]

Mon Apr 19 05:28:32 UTC 2004

I think something like this would be best (safest?) used on collection 
mx hosts.. hosts that clients would not connect with to send mail.. just 
other servers delivering mail inward.. I personally can't imagine why 
someone would want to use a win95/98/Me system as a mta.. so this 
probably would be a rather interesting idea worth testing out. If 
nothing else the collateral in the above scenario would probably be very 
low.

And of course the fingerprint list they have has a quite a few systems 
from aix to zaurus.

Patrick W.Gilmore wrote:

> 
> On Apr 18, 2004, at 11:40 PM, Matt Hess wrote:
> 
>> <late-night-humor>
>> I was amused at this and decided to look real quick.. OpenBSD's pf can 
>> block on OS fingerprints.. effectively doing exactly what you are 
>> kidding about (at least I'd hope so.. well, maybe) even in the man 
>> page example they put:
>>
>> # Do not allow Windows 9x SMTP connections since they are typically
>> # a viral worm. Alternately we could limit these OSes to 1 connection 
>> each.
>> block in on $ext_if proto tcp from any os {"Windows 95", "Windows 98"} \
>>       to any port smtp
>>
>> The OS fingerprint list they have is rather extensive..
>> </late-night-humor>
> 
> 
> Ya know, I do not think that is such a bad idea.
> 
> Does anyone have any stats on the number of "real" MTAs that use Win9x? 
>  Or of the "real" MTAs that show up as Win9x on this fingerprint?
> 