ipfw option `in` is not working on FreeBSD10

[lhmwzy]

Descriptionaccording to the man page, the rule option `in|out` are still
supported in FreeBSD10. But somehow the rule with in did not match anything
in my case.How-To-Repeatroot at FB10:~ # ipfw -f flush
Flushed all rules.
//Create rules <---------------------------------
root at FB10:~ # ipfw add count all from any to any MAC any any in via em0
00100 count ip from any to any MAC any any in via em0
root at FB10:~ # ipfw add count all from any to any MAC any any via em0
00200 count ip from any to any MAC any any via em0
//Check counters<-----------------------------------
root at FB10:~ # ipfw show
00100 0 0 count ip from any to any MAC any any in via em0
00200 26 2232 count ip from any to any MAC any any via em0
65535 3453 293448 allow ip from any to any

oot at FB10:~ # sysctl -a | grep net.link.ether.ipfw
net.link.ether.ipfw: 1