Question: Can a Slow Post HTTP attack be done from a single client?

The following source cites this line:
<https://medium.com/fantageek/understanding-socket-and-port-in-tcp-2213dc2e9b0c>

> 
> Ports are 16-bit numbers, therefore the maximum number of connections
> any given client can have to any given host port is 64K.
> 
> 
> 

But since the max. number of connections a server can handle is usually much greater than the above limit (around ~300k but scalable), I assume that the Slow Post HTTP attack can only be done as a DDoS attack (using more than 1 client).

But I can also see descriptions about Slow Post HTTP attack as DoS attack.
For eg. <https://blog.qualys.com/securitylabs/2011/11/02/how-to-protect-against-slow-http-attacks> states

> 
> Slow HTTP attacks are denial-of-service (DoS) attacks in which the
> attacker sends HTTP requests in pieces slowly, one at a time to a Web
> server.
> 
> 
> 

Please let me know if I am missing something.

Answer: 
Yes, a server can handle a lot of requests, but it is not handling just the attacker's requests. It is handling it's normal load, and these attacks are on top of that load.

It certainly is possible for a single attacker to exhaust *remaining* server resources, which means that this type of attack is correctly described as a non-DDoS attack. Yes, it might be enhanced by multiple nodes using this attack, but it's not a fundamental requirement.
Yes it can, in fact basically that type of attack tries to consume the internal memory that is handling the buffering of the post operation. In general the backends have parameters for handle this type of situations.