I have a simple socket server, that waits for a message and responds. How can I test this? Is there a client app or something that can help me send some data on a specific port to a server, and see the output? Telnet?
Simple telnet client works well for such tests. You can also try PuTTY in either Telnet or Raw connection modes. Both allow you to choose the port you want to connect to.
Also a tool like Microsoft Network Monitor is pretty useful to analyse the protocol's data flow if you don't have direct control (by logs) on what's being sent over the wire.
netcat should be able to handle anything you need to do with socket testing.
http://pctechtips.org/netcat-the-swiss-army-knife-useful-commands/#more-103
Windump - tcpdump works well, and has binaries available to Windows
You have several choices:
1) You can use Chrome or FireFox plugins such as:
Simple WebSocket Client
Smart WebSocket Client
2) You can use WebSocket or ReconnectingWebSocket in JavaScript. this is a simple test with WebSocket:
Open Chrome browser
Press F12 or Right Click on page then click Inspect Element to open developer console
You shoud see a window with several tabs. Go to console tab then write this code.
ws = new WebSocket('ws://<YOUR-DOMAIN>:<PORT>')
ws.send('STH YOU WANT TO SEND')
3) You can use websocket-client. It is a simple python library. You must install python and pip, then websocket-client via pip. This is a simple example:
Go to python shell and type.
from websocket import WebSocket
ws = WebSocket()
ws.connect('ws://<YOUR-DOMAIN>:<PORT>')
ws.send('STH YOU WANT TO SEND')
hit the command line, and just use telnet.
if you have a simple echo server, go to town.
Related
I have an application that I inherited that listens on port 7001 for UDP broadcasts from our in-house test equipment, and I recently updated another application that needs to do the same thing. Both applications must be able to coexist on the same computer.
Currently, when my recently updated application attempts to bind to the port to listen for UDP broadcasts and fails, it simply reports that the port is not available and suggests that the inherited application is probably running. How can I get my application to detect what application is actually listening on that port? I've done a Google search and have even searched this site, but so far I have been unable to find anything except to use Task Manager, TCPView, or netstat at the command line.
I would prefer a technique that either uses the Windows API or a Windows system COM component, since both applications are written in Visual Basic 6.0. (I know, I know, but I must maintain these applications since they are mission critical.) However, a .NET solution would would also be useful in case I need it in my new development efforts.
Use:
netstat -n -o
That will show the process ID and from there you can either look in the Task Manager's process viewer, go to menu View → Columns... and check the Process ID (PID). Then you can see the name of the process listening on that port.
Of course, you're wanting a programmatic way of accomplishing this and the GetTCPTable2 API is best as was already suggested. In fact, if you look at the IAT (Import Address Table) for netstat.exe, it actually uses that API to get that information.
There is a way to communicate directly with a command window and get its output using pipes and it would work fine, but the ideal way is to simply use the same API netstat uses.
I'm developing Firefox addon that communicate with external program by sockets. This program create local socket server on specified port when this addon need it. I would like to ckeck from this addon whether this application has opened this port already.
On Win7 when server isn't created yet I receive in socket created by addon NS_ERROR_CONNECTION_REFUSED in nsIRequestObserver::onStopRequest but if I can feel certain port isn't open when I receive this error?
You try to connect and see if the connection succeeds.
If it doesn't, then the port is not reachable (open).
That's the most obvious and easiest answer.
Other low-level solutions would require polling the OS itself somehow. That would be cross platform specific (so you'd need to write an implementation per platform) and also there is no API readily available so you'd have to mess around with C/C++ or at least js-ctypes, or hack together some ugly "execute this program and check output" stuff. All of which doesn't worth the fuzz.
If you want to find out which "inbound ports" are in use in windows you can use cmd,
if you don't know how to open cmd - open the run dialog by pressing windows-key+r. type cmd and hit enter
type netstat -a and hit enter and it will list all "listening" ports.
more info - http://www.techrepublic.com/blog/it-security/list-open-ports-and-listening-services/
So I've tested this particular example on my local machine:
http://bjorngylling.com/2011-04-13/postgres-listen-notify-with-node-js.html
It worked! So now when I update a specific table, and am running my node.js file(from the tutorial) -I get an instant notification on my Terminal(mac)!! cool!
But how do I implement this onto a client's browser??
First of all, in the node.js script you'll notice that I have to connect to the database with my username and password:
pgConnectionString = "postgres://username:pswd#localhost/db";
I obviously can't have that floating around in the .js file the user's browser downloaded.
Plus I don't even know what scripts I'd have to include in the <head>. I can't find anything anywhere on how this is used in the real world.... All I see are neat little examples you can use in your command line.
Any advice, or guidance in the right direction would be awesome! Thanks.
You can't.
Node.js runs directly on your server, speaking directly to the native libraries on that machine. I'm not sure exactly what the postgres driver you are using does, but either it speaks to the postgres libraries OR it speaks directly with sockets on the local or a remote database server.
Neither of these methods can be used directly from a browser environment (it can't speak directly to the native libraries and it can't speak "raw" sockets).
What you can do is to have the web client speak to your own server process on a server (running node.js or similar), which would then speak to the database on behalf of the client.
Assuming you also need to database server to be able to initiate notifications to the client, you would need to use a bi-directional communication module like socket.io or similar.
You can do: combine your JS running on node.js which accesses Postgres listening for events with a node.js based WebSocket server, implement PubSub and push out to HTML5 browsers .. WebSocket capable ones.
Another option: use a generic WebSocket to TCP bridge like https://github.com/kanaka/websockify and implement the Postgres client protocol in JS to run in browser. That is doable, but probably not easy / for the faint hearted.
I have written a small client server socket application. It is a proof of concept for some socket programming that I want to apply to a much bigger project.
For the moment I want to user wireshark to analyse the traffic that goes between them. They are both running on my local machine.
I have installed a loopback interface, and have tried to use wireshark with it.
No joy. Any ideas?
I have successfully analysed traffic between my machine and other machines no problems.
I have had a look here,
http://wiki.wireshark.org/CaptureSetup/Loopback
And I am not using the address 127.0.0.1 which they mention saying you can't capture traffic on 127.0.0.1
Thanks.
You might try creating a virtual machine to run your application and using wireshark on it.
Save yourself some grief and download Microsoft Network Monitor.
As good as Wireshark is on Unixen, Windows is a "special" case :)
What is the best way to access a running mono application via the command line (Linux/Unix)?
Example: a mono server application is running and I want to send commands to it using the command line in the lightest/fastest way possible, causing the server to send back a response (e.g. to stdout).
I would say make a small, simple controller program that takes in your required command line arguments and uses remoting to send the messages to the running daemon.
This would be similar to the tray icon controller program talking to the background service that is prevalent in most Windows service patterns.
Mono's gsharp tool is a graphical REPL that lets you Attach to Process.
#Rich B: This is definately a suitable solution, which I already had implemented - however on the server I have to use, the remoting approach takes around 350ms for a single request.
I've measured the time on the server side of the request handling - the request is handled in less than 10ms, so it has to be the starting of the client program and the tcp connection, that takes up the time.
Hence the hope that I can find another way to post the requests to the server application.
You can use the system.net.sockets abstractions to create a service on a TCP port, and then telnet to that port.
Check the library status page; Mono's coverage here is a bit patchy.