Hi

I was reading about data communication on the net and i got a little confused. There are 65535 available port numbers and the port numbers from 1-1024 are reserved for applications and such. That leaves 64511 ports available. My question is, when a web server has a number of connections from users which are larger than the amount of ports available, how can it handle more connections ? Every host that connects to the web server needs a source port, can several hosts share the same port numbers (and then the connections would be differentiated with the TCP ACK field and sequence numbers for example) ?

Thanks for all help.

A connection in the internet (a TCP connection) is always identified by two couples of numbers: (source address, source port), (destination address, destination port)
So, two different source addresses can have the same source port, as this results in two different connection identifiers.
A book about connections should absolutely explain this thing! If not, try complementing that book with some other source

If your webserver runs out of available ports to use for connections, it doesn't accept more until one becomes free. Typically this is called a Denial of Service (DoS).

Source ports are specific to the local machine. A single computer can't use the same source port for multiple applications at the same time, as the port would be already bound and reported as in-use to the OS. However, multiple computers connecting to the same destination could use the same source port.

thanks, great answers.