uRPF on FreeBSD

[Haesu]

Is there any reverse-path verification feature in FreeBSD kernel?

reverse-path verification as in uRPF (unicast reverse path filtering) widely
used for anti-ip-spoofing.

If it is supported, then does FreeBSD's uPRF implementation also allow loose
and strict check like on Cisco?  

Also... one last question that goes with this..
If uRPF feature is in FreeBSD, and if I route a prefix to ds0 (discard/null
interface "pseudo-device disc"), and a packet originates with source of a route
that is forwarded to ds0, would that invoke a verification drop? On Cisco, if
an origin packet has a source ip that's routed to Null0 or does not exist in
routing table (this is under loose check), then it would cause a verification
drop..

Thanks!
-hc

-- 
Haesu C.
TowardEX Technologies, Inc.
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