Python 来自不同虚拟IP的1024个连接后超时

我有一个问题，我已经挣扎了一段时间，但没有解决它

我正在实现一个流量生成器，它有一个客户端和一个服务器端。客户端模拟具有唯一IP地址的设备。这些IP作为虚拟接口添加到客户端，然后模拟设备将绑定到该客户端。然后，这些设备将连接到服务器端，并生成与服务器端的通信量

问题是我只能连接1023台设备，然后以下设备在连接时超时。我已经在服务器端签入wireshark，我可以看到连接的SYN，但应用程序中从未收到它。当我重新使用IPs时，使用的IPs少于2014个，我可以建立任意数量的连接

我创建了一个python程序，该程序更易于运行，并且存在相同的问题：

client.py

import socket
import thread
import time
from subprocess import call

TCP_IP = '192.168.169.218'
TCP_PORT = 9999
BUFFER_SIZE = 1024
MESSAGE = "-" * 1000

if __name__=='__main__':
    sockets = []
    for i in range(0, 10020):
        ip = "13.1."+ str(((i/254)%254) + 1) + "." + str((i % 254) + 1)
        cmd = "ip addr add " + ip + " dev eth1;"
        call(cmd, shell=True)
        s = socket.create_connection((TCP_IP, TCP_PORT), 10, (ip, 0))
        sockets.append(s)

    while 1:
        for s in sockets:
            s.send(MESSAGE)
            data = s.recv(BUFFER_SIZE)

    for s in sockets:
        s.close()

from socket import *
import thread

BUFF = 1024
HOST = '192.168.169.218'
PORT = 9999

def handler(clientsock,addr):
    while 1:
        data = clientsock.recv(BUFF)
        if not data: break
        clientsock.send(data)
        # type 'close' on client console to close connection from the server side
        if "close" == data.rstrip(): break     
    clientsock.close()
    print addr, "- closed connection" #log on console

if __name__=='__main__':
    count = 0   
    ADDR = (HOST, PORT)
    serversock = socket(AF_INET, SOCK_STREAM)
    serversock.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
    serversock.bind(ADDR)
    serversock.listen(5)
    while 1:
        print 'waiting for connection... listening on port', PORT
        clientsock, addr = serversock.accept()
        count += 1
        print count
        thread.start_new_thread(handler, (clientsock, addr))

server.py

import socket
import thread
import time
from subprocess import call

TCP_IP = '192.168.169.218'
TCP_PORT = 9999
BUFFER_SIZE = 1024
MESSAGE = "-" * 1000

if __name__=='__main__':
    sockets = []
    for i in range(0, 10020):
        ip = "13.1."+ str(((i/254)%254) + 1) + "." + str((i % 254) + 1)
        cmd = "ip addr add " + ip + " dev eth1;"
        call(cmd, shell=True)
        s = socket.create_connection((TCP_IP, TCP_PORT), 10, (ip, 0))
        sockets.append(s)

    while 1:
        for s in sockets:
            s.send(MESSAGE)
            data = s.recv(BUFFER_SIZE)

    for s in sockets:
        s.close()

from socket import *
import thread

BUFF = 1024
HOST = '192.168.169.218'
PORT = 9999

def handler(clientsock,addr):
    while 1:
        data = clientsock.recv(BUFF)
        if not data: break
        clientsock.send(data)
        # type 'close' on client console to close connection from the server side
        if "close" == data.rstrip(): break     
    clientsock.close()
    print addr, "- closed connection" #log on console

if __name__=='__main__':
    count = 0   
    ADDR = (HOST, PORT)
    serversock = socket(AF_INET, SOCK_STREAM)
    serversock.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
    serversock.bind(ADDR)
    serversock.listen(5)
    while 1:
        print 'waiting for connection... listening on port', PORT
        clientsock, addr = serversock.accept()
        count += 1
        print count
        thread.start_new_thread(handler, (clientsock, addr))

我运行的是CentOS 7.1 64位，我测试的Python版本是2.7.5

到目前为止我所做的：
-将打开的文件数限制（nofile）增加到1040000
-将net.core.somaxconn增加到65535
-将net.ipv4.tcp_max_syn_积压和net.core.netdev_max_积压增加到30000
-增加了核心和TCP缓冲区
-禁用防火墙并清除所有iptables规则

---

我测试了让python客户端在每次连接后休眠一秒钟，然后就没有问题了，所以我猜是有一些洪水防护措施。有人有什么想法吗？

有趣的问题，所以我用我的虚拟机做了一个测试。我发现，您的ARP邻居条目达到了极限

# sysctl -a|grep net.ipv4.neigh.default.gc_thresh
net.ipv4.neigh.default.gc_thresh1 = 128
net.ipv4.neigh.default.gc_thresh2 = 512
net.ipv4.neigh.default.gc_thresh3 = 1024

以上是默认值，当您的1024次连接填满此表时，垃圾收集器将再次开始运行arp，这会减慢速度并导致客户端超时

我可以如下设置这些值

net.ipv4.neigh.default.gc_thresh1 = 16384
net.ipv4.neigh.default.gc_thresh2 = 32768
net.ipv4.neigh.default.gc_thresh3 = 65536

---

瞧！！不再有1024个限制..HTH

这听起来像是tcp/ip堆栈的某种队列限制。也许这个链接可以给我们一些启示，但除此之外，我真的很无知。