Is this port open or blocked ??[Resolved]

**Pirate** · Sep 17th, 2003, 11:10 AM

How can I check if a speific port is open or blocked ? Don't tell me check Socket or web classes plz

Thanks

**Mike Hildner** · Sep 17th, 2003, 01:03 PM

Through code? There are also port scanner utilities, I use "Advanced Port Scanner", but there's a bunch of free/shareware.

**Pirate** · Sep 17th, 2003, 01:27 PM

I know there are a lot of utilities but I need some code for some reason which is part of big proj I'm working on ....

. Any ideas ?

thanks

**Mike Hildner** · Sep 17th, 2003, 01:58 PM

Why wouldn't you try with a socket? Seems easy enough.

**Pirate** · Sep 17th, 2003, 07:19 PM

Umm , I checked it and couldn't do anything or I'm not sure it would solve the problem so , Anyone ?

**PT Exorcist** · Sep 17th, 2003, 07:24 PM

lol
just try to host in the specified port and if u get an "port already in use" exception then it's being used......

**Pirate** · Sep 17th, 2003, 07:38 PM

Can you show me how because I've never used this class before ?

Thnanks .

**PT Exorcist** · Sep 18th, 2003, 07:26 AM

i really never done that before but tonight when i get home i can see if i can do that..it can't be too hard

**nemaroller** · Sep 18th, 2003, 09:05 AM

VB Code:

Dim tr As System.Net.Sockets.TcpListener = New System.Net.Sockets.TcpListener(8000) 'change 8000 to whatever port
        Try
            tr.Start()
        Catch ex As Exception
            System.Windows.Forms.MessageBox.Show(ex.ToString)
        End Try

**Pirate** · Sep 18th, 2003, 09:52 AM

nemaroller , first shows blue line under 'tr' declaration , though it run with no errors . After running this code , nothing happens , after clicking 1 more time , it shows this error :

System.Net.Sockets.SocketException: Only one usage of each socket address (protocol/network address/port) is normally permitted
at System.Net.Sockets.Socket.Bind(EndPoint localEP)
at System.Net.Sockets.TcpListener.Start()

What's the problem ?

**dynamic_sysop** · Sep 18th, 2003, 09:55 AM

System.Net.Sockets.SocketException: Only one usage of each socket address (protocol/network address/port) is normally permitted
at System.Net.Sockets.Socket.Bind(EndPoint localEP)
at System.Net.Sockets.TcpListener.Start()

What's the problem ?

it's throwing an error because the port is in use , which is how nemaroller meant it to work ( if you get the error message, then you know the port is in use )

**Pirate** · Sep 18th, 2003, 10:04 AM

No , you don't get it yet. If the port is being used and I clicked the buttton , it should throw the error right away not after the second click or the third . This doesn't seem to be reliable way . I need some API stuff if possible

.

Thanks

**Pirate** · Sep 18th, 2003, 10:26 AM

I tried these port numbers (1,80,81,21,8000,60000,1234) . Same error after two clicks nothing happens after 1 click !

**powdir** · Sep 18th, 2003, 11:09 AM

It's late and i am going home so forgive me if i am being thick-

BUT:

The first click claims the port the second is denied and an exception is generated - isn't that what your after?

Cheers...

**Pirate** · Sep 18th, 2003, 11:17 AM

Originally posted by powdir
It's late and i am going home so forgive me if i am being thick-
BUT:
The first click claims the port the second is denied and an exception is generated - isn't that what your after?
Cheers...

This error applies to all the port number I tried with . I assume port number (60000 or something like this) would be free since I've never seen an app uses this number and also larg values ranging from 2000 to 65xxx . I don't know if this make sense but....it doesn't solve the problem yet .

**PT Exorcist** · Sep 18th, 2003, 11:22 AM

sorry to say but it DOES really work..u said u tried with port 21 but do u have an ftp server?!

**Pirate** · Sep 18th, 2003, 11:27 AM

Originally posted by PT Exorcist
sorry to say but it DOES really work..u said u tried with port 21 but do u have an ftp server?!

lol , no but I was connecting to an ftp site

. Did you test it to say it works ?

**PT Exorcist** · Sep 18th, 2003, 11:29 AM

OMG

Dim tr As System.Net.Sockets.TcpListener = New System.Net.Sockets.TcpListener(21) 'change 8000 to whatever port

look at it

tcpLISTENER

this is HOSTING in your computer

this is to see if u have in YOUR computer any port open

i think u didnt quite explain what u wanted..u want to check in OTHER computer right?

sorry if i am being too agressive i have an headache..sorry

**Pirate** · Sep 18th, 2003, 11:34 AM

No , I want to detect if specific port number is open or blocked . That's all about . Again , I tested the code but it doesn't work for me at least . I don't if it's me or the code or the port .

**PT Exorcist** · Sep 18th, 2003, 11:34 AM

anyways here's the code

Code:

        Try
            Dim ts As System.Net.Sockets.TcpClient = New System.Net.Sockets.TcpClient("127.0.0.1", 654)
        Catch ex As System.Net.Sockets.SocketException
            If (ex.ErrorCode = 10061) Then
                MsgBox("The port isnt being used in the target machine")
            End If
        End Try

**PT Exorcist** · Sep 18th, 2003, 11:35 AM

Originally posted by Pirate
No , I want to detect if specific port number is open or blocked . That's all about . Again , I tested the code but it doesn't work for me at least . I don't if it's me or the code or the port .

but you want to check it in your computer or in a remote computer?

**Pirate** · Sep 18th, 2003, 11:39 AM

In my computer . ...

**Pirate** · Sep 18th, 2003, 11:43 AM

I think it just programmed to say ""The port isnt being used in the target machine" . I couldn't find any open port . I have norton antivirus but I don't think it's able to close all port and I can't believe all these ports are being used by any resource or program (0 through 65525 or so)

**PT Exorcist** · Sep 18th, 2003, 12:12 PM

using the other guy's code will check if in YOUR computer there is any port being used and yes it works, i tried with several ports and it did work.

my code checks in ANY computer(it can be remote or not) if a port is open(at least it tries to connect and if u get 10061 error code that means the computer machine refused the connection it will show the msg), then again i tried with several ports and it worked very well in all the ports

**Pirate** · Sep 18th, 2003, 03:43 PM

Originally posted by PT Exorcist
using the other guy's code will check if in YOUR computer there is any port being used and yes it works, i tried with several ports and it did work.

my code checks in ANY computer(it can be remote or not) if a port is open(at least it tries to connect and if u get 10061 error code that means the computer machine refused the connection it will show the msg), then again i tried with several ports and it worked very well in all the ports

What ports did you try ? and did you use the loopback ip or you internet IP ? for me it shows all ports I've tried are in use .

**Pirate** · Sep 18th, 2003, 04:25 PM

I used my internet IP and still same msg . Something is missing I think .

**Pirate** · Sep 18th, 2003, 05:07 PM

Actually , the error message confused me . I downloaded a tool that checks first for port opened and then I try them in my code . I found only 5 ports open and others are closed but I don't believe this . Maybe a lot of them are not configured not closed or something like this...lol

anyway it's sorted out . This code work .

VB Code:

Try
            Dim ts As System.Net.Sockets.TcpClient = New System.Net.Sockets.TcpClient("127.0.0.1", 654)
        Catch ex As System.Net.Sockets.SocketException
            If (ex.ErrorCode = 10061) Then
                MsgBox("The port [SIZE=3]is[/SIZE]  being used in the target machine")
            End If
        End Try

Thanks everyone for the time .

**PT Exorcist** · Sep 18th, 2003, 05:09 PM

glad to see my code worked

**nemaroller** · Sep 26th, 2003, 04:29 PM

Originally posted by Pirate
No , you don't get it yet. If the port is being used and I clicked the buttton , it should throw the error right away not after the second click or the third . This doesn't seem to be reliable way . I need some API stuff if possible .

Thanks

It doesn't error on the first click, because that port was not in use, and my code opened a port on it. The second time around, its in use, so then it errors.

If it doesn't error on the first click, then that port is available. I guess I should have mentioned you would want to close that port (tr.Close or tr.Stop don't remember which).

**Pirate** · Sep 27th, 2003, 11:47 AM

A question just came to my mind , How does it listen to the port ? I mean , does the port need to be opend to listen to ?

**PT Exorcist** · Sep 27th, 2003, 11:55 AM

Originally posted by Pirate
A question just came to my mind , How does it listen to the port ? I mean , does the port need to be opend to listen to ?

of course
otherwise any program would read other program's port and could do anything he wanted to

**Pirate** · Sep 27th, 2003, 11:59 AM

ah cool . thx

**tauhidshaikh** · Sep 28th, 2007, 07:21 AM

Hi everybody !!! This blog has been real helpful. I dont know if the thread is still alive. I might not get a reply back . Still giving it a try.

I am trying to do what "Pirate" was trying to do. The difference is, I am trying to Detect local as well as Remote PC's ports. I am trying to detect if the port (say 4000) is unblocked on the Local as well as a Remote PC. Please mind it, I am looking for bloceked/unblocked status and not open/close. Open means its in use and close means its not in use(But can be unblocked at the same time), because no service is being used on that port.

I could do Local machine port detection very well with the below mentioned code:
This works absolutely perfect guys. I installed a firewall on my local machine and tested the code. Perfect !!!
-----------------------------------------
by: nemaroller

Dim tr As System.Net.Sockets.TcpListener = New System.Net.Sockets.TcpListener(8000) 'change 8000 to whatever port
Try
tr.Start()
Catch ex As Exception
System.Windows.Forms.MessageBox.Show(ex.ToString)
End Try
--------------------------

The trouble is detecting the ports on Remote Computer

I tried using the code by PT Exorcist

--------------

Try
Dim ts As System.Net.Sockets.TcpClient = New System.Net.Sockets.TcpClient("127.0.0.1", 654)
Catch ex As System.Net.Sockets.SocketException
If (ex.ErrorCode = 10061) Then
MsgBox("The port isnt being used in the target machine")
End If
End Try
---------------

But it doesnt seem to work.

I am in a LAN connected over Switch and connected through a Router(Gateway) to the internet.

I tried to check a port on a remote machine, but without sending an access request to the remote machine, I said "The port isnt being used in the target machine"..

The code might be fine. am doing a little research on it. .

Still if you guys have any suggestion, I would really appreciate that.

I need a code for Checking if a port is blocked on Remote PC. (blocked/unblocked)

I am implementing the whole thing in C#. so C# or VB .Net would do ..

Thanks everybody,
Regards,

**danasegarane** · Sep 28th, 2007, 07:27 AM

Please dont push others thread.Create ur Own Thread.Normaly u wont get replies for a thread which is marked as resolved

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