How to Examine to find 18000 port availability on different random servers..
any programming ways in c..Any assistence
Thanks in Advance

do you know the program nmap?

Port scanning is not likely to make you particularly popular with the local network admins (and depending on the motivations behind it, may be off limits topic wise for this forum). If you have a legitimate need to monitor services on remote systems, I'd suggest looking into Nagios or similar.

ya similar wise i need to check a port availability on different remote servers..
can you assist me any ways

Actually, nmap is quite smart; you just specify port num to check using -p http://nmap.org/book/man-briefoptions.html.
That shouldn't upset anyone, assuming you should be doing this, although letting the local admins know is a good idea.

Definitely nmap is the way to go to just test if a port is open. You can use the -iL option to specify a list of hosts to scan. Nagios can do somewhat more detailed service checks, but its use may well be overkill for what you describe.

thanks very much for your important contribution of time..

i had one response on it.
in case of "nmap" and other tools we need to install another software package,which makes idea more dependent on other packages.
can we have any inbuilt mechanism to solve this through C programming using socket and all..

actually to get a response from other sockets we need to create socket on remote servers,responding to my client request.
that again makes complex.
so more or less "Is there any method to ping on remote servers checking specific IP free or not"

Thanks in advance

Do you know what service/protocol should be listening on 18000 at the remote sites?
If so, you can probably craft a simple client to check.
Otherwise try a simple telnet cxn and see what response you get.
Of course, it'd be simpler and more reliable to just ask the admins