Application by using more than 65535 UDP ports

Question

Hello all!
I'm now implementing a device simulator in VC++ to performance a load test to our server application. I need to simulate a huge number of devices to communicate with this server via UDP, each device shall have its own UDP port exclusive during the
simulation.
Since there are maximal 65536 ports pro IP address and from 0 to 1024 are reserved by OS, theoretically I have 64511 free ports for my Simulator application, considering some ports are required by some services/applications, the free port number may a little
fewer, I'm assuming this number is 60000. According to our software requirement, I can't reach the required simulating device amount under this port limitation.
If I'm right, if one computer has more IPs, I shall have more than 60000 free ports. My simulator runs under Windows Server 2008, 2 physical network adapters and I used following command to change the dynamic UDP port range to get 60000 UDP ports:
      netsh interface ipv4 set dynamicportrange protocol=udp startport=3000 numberofports=60000
My questions are:
1. Is this setting globally available or for each IP address?
   I tried to set the parameter "numberofports" to 120000 but it didn't work.
2. Shall I set for each IP address separately a UDP port range?
3. If this setting is for each IP addres available, I have following problem:
   For two IP address, I could bind 60000 ports in total to 60000 UDP sockets, e.g IP1 20000 ports and IP2 40000 ports, or IP1 40000 ports and IP2 20000 ports. That means I can still use maximal 60000 UDP ports.
Unfortunately, I can't find any reference about this topic in Internet, does anyone have my similar situation?
Thank you in advance to teach me a solution!

Answer 1

" I need so many UDP ports because our product has "state", and our Server application maintains connection sessions for each connected device."
Couldn't you add some information to the datagrams that identify the state? That may require less resources than creating a zillion of sockets. Though I suppose that using a single socket would lead to serialization and that will hurt scaling...
"How much memory does one socket need? I didn't think about this topic....."
Hmm, memory is need for the socket data structures and buffers. Probably a few kilobytes. Let's do a test and see what happens:
#include <winsock2.h>
#include <cstdio>
#pragma comment(lib, "ws2_32.lib")
DWORD WINAPI ServerThread(LPVOID addr) {
SOCKET sk = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (sk == INVALID_SOCKET) {
printf("socket failed\n");
return 1;
int err = bind(sk, static_cast<sockaddr *>(addr), sizeof(sockaddr_in));
if (err != 0) {
printf("bind failed\n");
return 1;
char buffer[256];
sockaddr_in from;
int fromLen = sizeof(from);
for (;;) {
int length = recvfrom(sk, buffer, 256, 0, reinterpret_cast<sockaddr *>(&from), &fromLen);
printf("got %d bytes from %s:%d\n", length, inet_ntoa(from.sin_addr), htons(from.sin_port));
int main() {
WSADATA wsaData;
int err = WSAStartup(MAKEWORD(2, 2), &wsaData);
sockaddr_in to;
to.sin_family = AF_INET;
to.sin_port = htons(4242);
to.sin_addr.S_un.S_addr = inet_addr("192.168.1.68");
CreateThread(nullptr, 0, ServerThread, &to, 0, nullptr);
const char *addrs[] { "192.168.1.40", "192.168.1.41", "192.168.1.42", "192.168.1.43" };
SOCKET sockets[_countof(addrs)][30000];
sockaddr_in from;
from.sin_family = AF_INET;
int count = 0;
for (int i = 0; i < _countof(addrs); i++) {
from.sin_addr.S_un.S_addr = inet_addr(addrs[i]);
for (int j = 0; j < _countof(sockets[i]); j++) {
SOCKET sk = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
from.sin_port = htons(65535 - j);
err = bind(sk, reinterpret_cast<sockaddr *>(&from), sizeof(from));
if (err != 0) {
printf("bind failed while creating socket %d on %s:%d\n", count, addrs[i], 65535 - j);
closesocket(sk);
sk = INVALID_SOCKET;
else {
count++;
sockets[i][j] = sk;
printf("created %d sockets\n", count);
char buffer[256];
for (int i = 0; i < _countof(sockets); i++) {
for (int j = 0; j < _countof(sockets[i]); j++) {
if (sockets[i][j] != INVALID_SOCKET)
err = sendto(sockets[i][j], buffer, 256, 0, reinterpret_cast<sockaddr *>(&to), sizeof(to));
This creates almost 120000 sockets on my machine (Win 8.1). All the 192.168.1.x addresses are on the same network adapter, 4 of them are used for "clients" and 1 for the "server". Clients have ports in the range 35535 - 65535 so you get
around 30000 sockets per address (a few ports are in use so you won't get exactly 30000 unless you adjust the code).
When the program starts the kernel non paged pool jumps from ~50MB to ~200MB. That means around 1.3KBytes per socket.
@Joel Engineer: "The windows operating system can only have one IP per Computer name and a computer can only have one name..."
You're delusional.