Bugtraq mailing list archives

Re: Small TCP packets == very large overhead == DoS?


From: Darren Reed <avalon () coombs anu edu au>
Date: Tue, 10 Jul 2001 08:28:06 +1000 (Australia/ACT)

In some mail from gregory duchemin, sie said:

hello,

know if the TCP silly window syndrome might be used too ?
Uploading/downloading files byte per byte to/from a remote ftp server with a 
stupid window size of one byte may generate a very high overhead.

Silly window sizes aren't so bad.  If you have a window size of one then
you only ever have one outstanding piece of data sent at a time.  So if
I have 16k of data, it might take 32k or more packets, but I can only send
one packet at a time.

In contrast, if I have a window of 16384 but the TCP MSS is only 1, I can
send all 16384 bytes now, each in their own packet, and more as I get ACKs
from the receiver.

Darren


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