BugTraq
Re: (ICMP attacks against TCP) (was Re: HPSBUX01137 SSRT5954 rev.4 - HP-UX TCP/IP Remote Denial of Service (DoS)) Jul 21 2005 05:36PM
Dennis Lubert (plasmahh informatik uni-bremen de)
At 00:09 20.07.2005, Fernando Gont wrote:

>The IPv4 minimum MTU is 68, and not 576. If you blindly send packets
>larger than 68 with the DF bit set, in the case there's an intermmediate
>with an MTU lower that 576, the connection will stall.
>
>576 is the minimum reassembly buffer size. That is the minimum packet size
>every *end-system* should be able to reassemble, and NOT the minimum
>packet size that can get to destination without fragmentation.

To be completely correct
<quote RFC 791>
Every internet module must be able to forward a datagram of 68 octets
without further fragmentation. This is because an internet header my be up
to 60 octets, and the minimum fragment is 8 octets.
Every internet destination must be able to receive a datagram of 576 octets
either in one piece or in fragments to be reassembled.
</quote>

So 576 is the minimum packet size you can get to a destination without
fragmentation

Carpe quod tibi datum est

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