> How can you solve it in the core code when it's the box you're going
> through which is causing the problem?  You can solve it either by
> disabling the advanced features (building a new kernel), or updating
> the networking code in the problem machine to modern standards.

Here, "modern standards" probably means "compliant with RFC 1122 section
4.2.2.5".  RFC1122, published in 1989, says that unrecognised TCP options
must be ignored.  RFC793, published in 1981, says "A TCP must implement
all options" (presumably meaning "all options defined in RFC793"), and
makes no explicit provision for additional options defined later. 

--apb (Alan Barrett)