[unisog] UDP fragments anyone?
r.fulton at auckland.ac.nz
Tue Feb 20 19:17:15 GMT 2007
Stephen John Smoogen wrote:
> Vijay S Sarvepalli VSSARVEP wrote:
>> Anybody care to share their concerns on UDP fragments across their
>> perimeter? It seems like there is no
>> valid traffic that needs it. eMule ? I am not sure if there are only
>> P2P use it.
> My normal mode of activity is to drop UDP and ICMP fragments at any
> border where I am going to use detection tools to examine traffic.
> Fragmented UDP and ICMP are normally used to evade various tools and in
> legitimate traffic a sign of something broken.
any tools worth their salt will reassemble packets *before* examining
the contents and will flag overlapping fragments. I don't see this as a
valid argument for dropping UDP fragments. Our fireall (OpenBSD's pf)
actually does the reassembly at the border which is another way of
dealing with the issue.
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