[Bug 48] conntrack breaks udp path mtu discovery

bugzilla-daemon@netfilter.org bugzilla-daemon@netfilter.org
Wed, 25 Feb 2004 15:37:21 +0100


https://bugzilla.netfilter.org/cgi-bin/bugzilla/show_bug.cgi?id=48





------- Additional Comments From laforge@netfilter.org  2004-02-25 15:37 -------
Yes, the 'saving all fragment sizes' approach is just too complex.  It's just a
theoretical option.

Saving the maximum fragment size would work, yes.  However, where would we store
it?   This cannot be done by the connection tracking code, since it just hands
off all fragments to the normal IPv4 ip_defrag(), with no way knowing what the
resulting skb's address might be (before the packet is completed).

Hacking ip_fragment to store this kind of information would most likely not go
into the mainstream kernel.  This means we would have to invent defragmentation
on our own :(

There simply is no satisfactory solution, I have to admit.



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