On Thu, 19 Jul 2018 07:34:36 +0900,
Thomas William wrote:
>
> [1 <multipart/alternative (7bit)>]
> [1.1 <text/plain; UTF-8 (7bit)>]
> Hello, I've been having a problem for days, I can not capture tcp packets
> with the controller.
> My topology is below:
>
> +---------------------------+
> | |
> | C0 - Controller |
> | |
> +-------------+-------------+
> c0-eth0
> |
> |
> +-+--+--+-+ +-+--+--+
> | Switch | ---------------- | H2 |
> +-+--+--+-+ +-+--+--+
> |
> |
> s1-eth0.2
> +-------------+-------------+------+
> | |
> | S1 - OpenFlow AP |
> | |
> | |
> +-+----------+----------+---+
> s1-eth0.1
> +
> |
> |
> v
> h1-eth0
> +-+--+
> | H1 |
> +-+--+
>
> I want to modify tcp packets sent by server h1 to another h2 server
> connected to the common switch, but when I print the packages, there is no
> tcp package, just other types of packages like udp, dhcp, igmp, ipv4, ipv6. I
> have no idea why, I'd like the opinion of you.
>
> My code is below, just an example to test here:
>
> from ryu.base import app_manager
> # from ryu.ofproto import ofproto_v1_0
> from ryu.ofproto import ofproto_v1_5
> from ryu.lib.packet import packet
> from ryu.lib.packet import ethernet
> from ryu.lib.packet import ipv4
> from ryu.lib.packet import tcp
> from ryu.controller import ofp_event
> from ryu.controller.handler import MAIN_DISPATCHER, CONFIG_DISPATCHER
> from ryu.controller.handler import set_ev_cls
> from ryu.topology import event
>
> #iperf tcp example
>
> class L2Forwarding(app_manager.RyuApp):
> # OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]
> OFP_VERSIONS = [ofproto_v1_5.OFP_VERSION]
>
> def __init__(self, *args, **kwargs):
> super(L2Forwarding, self).__init__(*args, **kwargs)
>
> @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
> def switch_features_handler(self, ev):
> datapath = ev.msg.datapath
> ofproto = datapath.ofproto
> parser = datapath.ofproto_parser
> print("install the table-miss flow entry")
> # install the table-miss flow entry.
> match = parser.OFPMatch()
> actions = [parser.OFPActionOutput(ofproto.OFPP_CONTROLLER,
> ofproto.OFPCML_NO_BUFFER)]
> self.add_flow(datapath, 0, match, actions)
>
> def add_flow(self, datapath, priority, match, actions):
> ofproto = datapath.ofproto
> parser = datapath.ofproto_parser
> print("construct flow_mod message and send it")
> # construct flow_mod message and send it.
> inst = [parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS,
> actions)]
> mod = parser.OFPFlowMod(datapath=datapath, priority=priority,
> match=match, instructions=inst)
> datapath.send_msg(mod)
>
>
> @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
> def packet_in_handler(self, ev):
> msg = ev.msg # Object representing a packet_in data
> structure.
> datapath = msg.datapath # Switch Datapath ID
> ofproto = datapath.ofproto # OpenFlow Protocol version the entities
> negotiated. In our case OF1.3
> parser = datapath.ofproto_parser
> out_port = ofproto.OFPP_LOCAL
> in_port = ofproto.OFPP_LOCAL
>
> pkt = packet.Packet(msg.data)
> eth = pkt.get_protocol(ethernet.ethernet)
>
> dst = eth.dst
> src = eth.src
>
> print(pkt.get_protocol)
>
> self.logger.info("packet in %s %s", src, dst)
>
> v4 = pkt.get_protocol(ipv4.ipv4)
> if v4:
> print("IPV4: %s ==> %s " % (v4.src, v4.dst))
>
> server_ip = v4.dst
> in_port = msg.match['in_port']
>
> if pkt.get_protocol(tcp.tcp):
You are discarding tcp packet data here.
You'd want to:
pkt_tcp = pkt.get_protocol(tcp.tcp)
if pkt_tcp:
src_port = pkt_tcp.src_port
> src_port = pkt.src_port
> print("TCP GET %s", "=" * 100)
>
> #Match in protocol tcp "in_proto=6" and ipv4
> "eth_type=0x0800"
> match_tcp = parser.OFPMatch(in_port=in_port,
> eth_type=0x0800, ip_proto=6, tcp_flags=0x010, ipv4_dst=server_ip,
> tcp_src=src_port)
> actions =
> [datapath.ofproto_parser.OFPActionOutput(out_port)]
>
> self.add_flow(datapath, 1, match_tcp, actions)
--
IWAMOTO Toshihiro
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