Certain 4.2 BSD derived systems do indeed drop all connections to that
destination. Its a bug on their part and very exploitable as Im sure
you can imagine.
> Hmm, shouldn't we be useing one of the higher (uncommented, 6-12) numbers
> in the codes for UNREACH section in <linux/icmp.h> ?
Someone was supposed to be testing the effect of the newer options on old
stacks and seeing what occured. I've not heard anything back yet.