Running out of ports

[alxhotel]

[OFFTOPIC]

I know this is not directly related to uWebsockets, but I was reading your article and it mentions the need to have multiple IP addresses to run the experiment:

for i in {135..185}; do sudo ip addr add 192.168.0.$i/24 dev wlp3s0; done

I'm wondering how to do this same thing in a public VPS, where you only have 1 public IP address. In other words, what is the best way to avoid running out of ports in a public server?

(Btw, I'm running my uWebsocket server behind a Nginx proxy in the same machine.)

Thanks in advance

[ghost]

One IP adress can only have 65k connections, that's a hard theoretical limit since ports are represented as 16 bit unsigned integers. You literally have to severe using multiple IP addresses.

[alxhotel]

Ok. The thing is that when I run the command netstat -nat, it returns all the TCP connections like this:

tcp    0    0    [PUBLIC IP]:443   [CLIENT IP]:[RANDOM PORT]      ESTABLISHED

And since a TCP connection is defined as these 4 tuples, I don't see where I'm running out of ports. Since my server is only using the port 443.

[ghost]

Hmm I think I mixed them up myself...

Right, the client needs multiple IP addresses, not the server. My bad, I think?

[ghost]

I'm confused. Honestly I have no idea right now ;)

[ghost]

Ah.

Either you need multiple IP addresses server side, or you need to connect from multiple IP addresses client side. You can't have one IP server side and one IP client side and expect to go beyond 65k or even close to that

[alxhotel]

Ah gotcha, it makes sense now.

Thanks :)