實驗3：OpenFlow協定分析實踐
一、實驗目的
能夠運用 wireshark 對 OpenFlow 協定資料互動過程進行抓包；
能夠借助包解析工具，分析與解釋 OpenFlow協定的資料包互動過程與機制。
二、實驗環境
下載下傳虛拟機軟體Oracle VisualBox；
在虛拟機中安裝Ubuntu 20.04 Desktop amd64，并完整安裝Mininet；
三、實驗基本要求
1.搭建下圖所示拓撲，完成相關 IP 配置，并實作主機與主機之間的 IP 通信。用抓包軟體擷取控制器與交換機之間的通信資料包。
- h1:192.168.0.101/24
- h1:192.168.0.102/24
- h1:192.168.0.103/24
- h1:192.168.0.104/24
2.wireshark抓包結果
- 控制器6633端口（我最高能支援OpenFlow 1.0）-->交換機54256端口
- 交換機54256端口（我最高支援OpenFlow 1.5）-->控制器6633端口
實驗3：OpenFlow協定分析實踐 - 控制器6633端口（我需要你的特征資訊）--> 交換機54256端口
實驗3：OpenFlow協定分析實踐 - 控制器6633端口（請按照我給你的flag和max bytes of packet進行配置）--> 交換機54256端口
實驗3：OpenFlow協定分析實踐
3.回答：交換機與控制器建立通信時是使用TCP協定還是UDP協定？
TCP協定
四、實驗進階要求
-
将抓包結果對照OpenFlow源碼，了解OpenFlow主要消息類型對應的資料結構定義。
Features Reply交換機54256端口（這是我的特征資訊，請查收）-- 控制器6633端口
代碼
/* Description of a physical port */
struct ofp_phy_port {
uint16_t port_no;
uint8_t hw_addr[OFP_ETH_ALEN];
char name[OFP_MAX_PORT_NAME_LEN]; /* Null-terminated */
uint32_t config; /* Bitmap of OFPPC_* flags. */
uint32_t state; /* Bitmap of OFPPS_* flags. */
/* Bitmaps of OFPPF_* that describe features. All bits zeroed if
* unsupported or unavailable. */
uint32_t curr; /* Current features. */
uint32_t advertised; /* Features being advertised by the port. */
uint32_t supported; /* Features supported by the port. */
uint32_t peer; /* Features advertised by peer. */
};
OFP_ASSERT(sizeof(struct ofp_phy_port) == 48);
/* Switch features. */
struct ofp_switch_features {
struct ofp_header header;
uint64_t datapath_id; /* Datapath unique ID. The lower 48-bits are for
a MAC address, while the upper 16-bits are
implementer-defined. */
uint32_t n_buffers; /* Max packets buffered at once. */
uint8_t n_tables; /* Number of tables supported by datapath. */
uint8_t pad[3]; /* Align to 64-bits. */
/* Features. */
uint32_t capabilities; /* Bitmap of support "ofp_capabilities". */
uint32_t actions; /* Bitmap of supported "ofp_action_type"s. */
/* Port info.*/
struct ofp_phy_port ports[0]; /* Port definitions. The number of ports
is inferred from the length field in
the header. */
};
- Packet_in交換機54256端口（有資料包進來，請訓示）--控制器6633端口
點選檢視代碼
/* Why is this packet being sent to the controller? */
enum ofp_packet_in_reason {
OFPR_NO_MATCH, /* No matching flow. */
OFPR_ACTION /* Action explicitly output to controller. */
};
/* Packet received on port (datapath -> controller). */
struct ofp_packet_in {
struct ofp_header header;
uint32_t buffer_id; /* ID assigned by datapath. */
uint16_t total_len; /* Full length of frame. */
uint16_t in_port; /* Port on which frame was received. */
uint8_t reason; /* Reason packet is being sent (one of OFPR_*) */
uint8_t pad;
uint8_t data[0]; /* Ethernet frame, halfway through 32-bit word,
so the IP header is 32-bit aligned. The
amount of data is inferred from the length
field in the header. Because of padding,
offsetof(struct ofp_packet_in, data) ==
sizeof(struct ofp_packet_in) - 2. */
};
- Flow_mod控制器通過6633端口向交換機54408端口、交換機54386端口下發流表項、指導資料的轉發處理
/* Fields to match against flows */
struct ofp_match {
uint32_t wildcards; /* Wildcard fields. */
uint16_t in_port; /* Input switch port. */
uint8_t dl_src[OFP_ETH_ALEN]; /* Ethernet source address. */
uint8_t dl_dst[OFP_ETH_ALEN]; /* Ethernet destination address. */
uint16_t dl_vlan; /* Input VLAN id. */
uint8_t dl_vlan_pcp; /* Input VLAN priority. */
uint8_t pad1[1]; /* Align to 64-bits */
uint16_t dl_type; /* Ethernet frame type. */
uint8_t nw_tos; /* IP ToS (actually DSCP field, 6 bits). */
uint8_t nw_proto; /* IP protocol or lower 8 bits of
* ARP opcode. */
uint8_t pad2[2]; /* Align to 64-bits */
uint32_t nw_src; /* IP source address. */
uint32_t nw_dst; /* IP destination address. */
uint16_t tp_src; /* TCP/UDP source port. */
uint16_t tp_dst; /* TCP/UDP destination port. */
};
/* Flow setup and teardown (controller -> datapath). */
struct ofp_flow_mod {
struct ofp_header header;
struct ofp_match match; /* Fields to match */
uint64_t cookie; /* Opaque controller-issued identifier. */
/* Flow actions. */
uint16_t command; /* One of OFPFC_*. */
uint16_t idle_timeout; /* Idle time before discarding (seconds). */
uint16_t hard_timeout; /* Max time before discarding (seconds). */
uint16_t priority; /* Priority level of flow entry. */
uint32_t buffer_id; /* Buffered packet to apply to (or -1).
Not meaningful for OFPFC_DELETE*. */
uint16_t out_port; /* For OFPFC_DELETE* commands, require
matching entries to include this as an
output port. A value of OFPP_NONE
indicates no restriction. */
uint16_t flags; /* One of OFPFF_*. */
struct ofp_action_header actions[0]; /* The action length is inferred
from the length field in the
header. */
};
- Packet_out控制器6633端口（請按照我給你的action進行處理）-->交換機54408端口
/* Action header that is common to all actions. The length includes the
* header and any padding used to make the action 64-bit aligned.
* NB: The length of an action *must* always be a multiple of eight. */
struct ofp_action_header {
uint16_t type; /* One of OFPAT_*. */
uint16_t len; /* Length of action, including this
header. This is the length of action,
including any padding to make it
64-bit aligned. */
uint8_t pad[4];
};
OFP_ASSERT(sizeof(struct ofp_action_header) == 8);
/* Send packet (controller -> datapath). */
struct ofp_packet_out {
struct ofp_header header;
uint32_t buffer_id; /* ID assigned by datapath (-1 if none). */
uint16_t in_port; /* Packet's input port (OFPP_NONE if none). */
uint16_t actions_len; /* Size of action array in bytes. */
struct ofp_action_header actions[0]; /* Actions. */
/* uint8_t data[0]; */ /* Packet data. The length is inferred
from the length field in the header.
(Only meaningful if buffer_id == -1.) */
};
五、個人心得
通過這次實驗，使我對抓包和分析openflow的資料包互動過程更加熟悉，。在實際操作的過程中我遇到了一個問題是，進行pingall操作後，并沒有在wireshark中發現hello包，然後删了又重新做還是不行，最後查找資料，發現是應該先打開wireshark，在進行pingall操作才會正常，雖然是一個小問題但是确實影響心情。。。。。。。其餘就是查找資料的過程比較麻煩，要利用過濾工具，就會事半功倍。