在SDN和POX控制器中检测和缓解TCP SYN Flood攻击的Python代码

from pox.core import core
import pox.openflow.libopenflow_01 as of

# 定义全局变量
SYN_THRESHOLD = 100  # SYN请求阈值
SYN_TIMEOUT = 10  # SYN请求超时时间（秒）

# 定义控制器类
class SYNController(object):
    def __init__(self):
        self.connection = None
        self.syn_count = {}  # 记录每个源IP的SYN请求数量

    def _handle_ConnectionUp(self, event):
        self.connection = event.connection

    def _handle_PacketIn(self, event):
        packet = event.parsed
        if packet.find('tcp'):
            tcp = packet.find('tcp')
            if tcp.SYN and not tcp.ACK:
                src_ip = packet.srcip.toStr()
                if src_ip in self.syn_count:
                    self.syn_count[src_ip] += 1
                else:
                    self.syn_count[src_ip] = 1

                if self.syn_count[src_ip] > SYN_THRESHOLD:
                    self._block_ip(src_ip)

    def _block_ip(self, ip):
        # 使用OpenFlow规则阻止源IP的流量
        msg = of.ofp_flow_mod()
        msg.match.dl_type = 0x0800  # IPv4
        msg.match.nw_src = ip
        self.connection.send(msg)

        # 设置超时时间，超时后解除阻止
        core.callDelayed(SYN_TIMEOUT, self._unblock_ip, ip)

    def _unblock_ip(self, ip):
        # 移除阻止源IP的OpenFlow规则
        msg = of.ofp_flow_mod()
        msg.match.dl_type = 0x0800  # IPv4
        msg.match.nw_src = ip
        msg.command = of.OFPFC_DELETE
        self.connection.send(msg)

        # 清除计数器
        del self.syn_count[ip]

# 启动控制器
def launch():
    core.registerNew(SYNController)