regarding winsock close event

[asmdev]

hi, i wish to enquire a bit information regarding winsock close event.

let say, if we created a tcp server which able to accept multiple connection on port 80.

let say, a client connected to port 8080, we create a new socket and direct the client to the new sock with random port.

  Proto  Local Address          Foreign Address        State
  TCP    0.0.0.0:8080           0.0.0.0:0              LISTENING
  TCP    127.0.0.1:1728         127.0.0.1:8080         ESTABLISHED
  TCP    127.0.0.1:8080         127.0.0.1:1728         ESTABLISHED

so we got something like above when we netstat. now let say, the client program was not written properly, it didn't close it socket after the application shutdown. so, let say if i terminate the client application now, what i got in netstat is like below.

  Proto  Local Address          Foreign Address        State
  TCP    127.0.0.1:1728         127.0.0.1:8080         FIN_WAIT_2
  TCP    127.0.0.1:8080         127.0.0.1:1728         CLOSE_WAIT

so, since most of the winsock tutorial site teach us to write server that create a new sock based on (when sckClosed socket was not found in current winsock control array) so, when a new client try to connect us, our server create a new socket for it.

now, my question is, does this mean, somebody could (i mean fill up our server winsock control array which is 65536 only using such technique?)

[Mike Stefanik]

The CLOSE_WAIT state is perfectly normal. For more information about it, a good resource is the Winsock Programmer's FAQ:

http://tangentsoft.net/wskfaq/articl...gging-tcp.html

It would be good to read the whole page, but you can skip on down to the section that talks about TIME-WAIT for more insight into what's going on.

[asmdev]

thanks mike for ur repond.
eventually, i have coded a client which try to create multiple sock connection
well, my server application seem quite slow when the connection reach about 400. (i am on a pentium 4 with 256 MB ram)

is this normal? i guess it is quite hard to hack the server to reach 65536 concurrent connection.

[Mike Stefanik]

The total number of sockets that you can create on Windows NT/2K/XP depends on the amount of physical memory you have (socket handles are allocated from the non-paged pool). Depending on what platform you're using, you can probably get about 3000-5000 connections; however, to approach those numbers, you're looking at writing a multithreaded program in C/C++ and using overlapped I/O.