List of things that don’t support Flowspec:
1) Quagga does not support flowspec
2) Juniper SRX does not support flowspec
3) ExaBGP supports flowspec but is not a listening service – it establishes connections only (note as of 1/13/2014 ExaBGP does support listening services but I have not yet tested it)
4) Cisco does not support flowspec
So – if you want to play with FlowSpec — it looks like a high end Juniper router and ExaBGP are two good choices.
Maybe an olive vm would also work?