Batch file to check the availability of a specific port of a remote server

Question

Hi I am trying to make a bat file to check the availability from different servers to a specific one, in order to check if there are some firewalls between them,or something that blocks the conecction. The thing is I can't use third parties software like portqry, nmap ... So iam stuck here, every tip will be helpfull.

Thanks in advance XD,

Answer 1

manually you can use telnet

echo.|telnet google.com 80

But telnet output cannot be handles so it's not useful for scripting.

Here's one solution which is more or less cheating (as it creates an .exe file) , but is not downloades. As it contains binary data into hex string it's a little bit long ,so I'd had to use pastebin.com

Another way.Using jscript.net/batch hybrid (should be saved as bat) which also creates a small exe file. But setting socket connection timeout is not so trivial task so if the port is not availble it will be waiting a little bit too long:

@if (@X)==(@Y) @end /****** silent line that start jscript comment ******

@echo off
::::::::::::::::::::::::::::::::::::
:::       compile the script    ::::
::::::::::::::::::::::::::::::::::::
setlocal
::if exist portchk.exe goto :skip_compilation

set "frm=%SystemRoot%\Microsoft.NET\Framework\"
:: searching the latest installed .net framework
for /f "tokens=* delims=" %%v in ('dir /b /s /a:d /o:-n "%SystemRoot%\Microsoft.NET\Framework\v*"') do (
    if exist "%%v\jsc.exe" (
        rem :: the javascript.net compiler
        set "jsc=%%~dpsnfxv\jsc.exe"
        goto :break_loop
    )
)
echo jsc.exe not found && exit /b 0
:break_loop


%jsc% /nologo /out:"portchk.exe" "%~dpsfnx0"
::::::::::::::::::::::::::::::::::::
:::       end of compilation    ::::
::::::::::::::::::::::::::::::::::::
:skip_compilation

:: download the file


 ::::just change the link and the file::::
 portchk.exe google.com 80
 portchk.exe google.com 666


exit /b 0


****** end of jscript comment ******/

import System;
import System.Net.Sockets;
import System.Timers;

var arguments:String[] = Environment.GetCommandLineArgs();



var remote_host=arguments[1];
var remote_port=arguments[2];

//var ipa= (IPAddress) Dns.GetHostAddresses(remote_host)[0];

var sock=new System.Net.Sockets.Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);

try {
    sock.Connect(remote_host, remote_port);
    //sock.ConnectAsync(remote_host, remote_port);
    timer_connection = new Timer();

    Console.WriteLine("connected to something");

}catch (e) {

    Console.WriteLine("Port is probably not available");
}