Hi Eric,

On 26.03.20 18:58, Eric Robinson wrote:
> Greetings,
> Many people say the maximum number of client ports is 64K. However, TCP 
> connections only require unique sockets, which are defined as...
> local_IP:local_port -> remote_ip:remote_port
> Theoretically, it is possible for a client process to keep using the same 
> local source port, as long as the connections are to a unique destinations. 
> For example on a local machine, the following connections should be 
> possible...
> ->
> ->
> ->
> ->
> I've seen this demonstrated successfully here:
> https://serverfault.com/questions/326819/does-the-tcp-source-port-have-to-be-unique-per-host
> As someone on that page pointed out, while it is possible, it does not 
> commonly occur in practice "because most TCP APIs don't provide a way to 
> create more than one connection with the same source port, unless they have 
> different source IP addresses." This leads to the 64K maximum client port 
> range, but it is really a limitation of the APIs, not TCP.
> So how does tomcat handle things? Is it limited to a maximum 64K client 
> source ports, or is it 64K per destination, as it should be?

To be honest, I can't remember to have seen a web- or application server
that accepts 64K concurrent connections at all, let alone to a single

I can't come up with any reason to do so, I'd assume that there's a DOS
attack if I get 100 concurrent incoming connections from a single IP,
and a programming error if the server sets up more than 1K outgoing

Maybe I'm missing the obvious, or have only administered meaningless
installations, but I fail to see the real world relevance of this question.

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