Scapy on PlanetLab
Not sure if this will help but in my experience in order to receive packets in scapy, you have to use the sr or sr1 method:
sr1(IP(dst="192.168.1.8")/UDP(dport=60112))
Begin emission:...Finished to send 1 packets.Received 4 packets, got 1 answers, remaining 0 packets
<IP version=4L ihl=5L tos=0xc0 len=56 id=47804 flags= frag=0L ttl=64 proto=icmp chksum=0x6274 src=192.168.1.8 dst=192.168.1.2 options='' |<ICMP type=dest-unreach code=3 chksum=0x59eb unused=0 |<IPerror version=4L ihl=5L tos=0x0 len=28 id=1 flags= frag=0L ttl=64 proto=udp chksum=0x1dfc src=192.168.1.2 dst=192.168.1.8 options='' |<UDPerror sport=domain dport=60112 len=8 chksum=0xb803 |>>>>The sr() function is for sending packets and receiving answers. The function returns a couple of packet and answers, and the unanswered packets. The function sr1() is a variant that only return one packet that answered the packet (or the packet set) sent. -Source