Does windows closes idle sockets? I mean if I'm a client connecting to a service on Windows server, is it possible that Windows server closes the connection after certain idle-time?
If yes, how to change this behaviour, or at least change the idle-time value?
Thanks in advance.
The behavior depends on the SO_KEEPALIVE socket option. Here's the MSDN page about it. After some further digging you can adjust the KEEPALIVE semantics with a WSAIoctl and the SIO_KEEPALIVE_VALS Control Code.
I find, that if you control both ends, it is usually better to implement keepalive messages as part of the protocol used to communicate between the client and server instead of relying on SO_KEEPALIVE.
I would imagine that depends on the protocol, implementation and perhaps server config.
PuTTY has an option to prevent timing out of SSH sessions by periodically sending null packets to the server - I suspect this is a simply packet with no actual payload. Perhaps you could implement something like this?
On MSDN you will find that the defaul keep-alive timeout is set to 2 hours. You are maybe able to manipulate this by using setsockopt/SO_SNDTIMEO/getsockopt
Related
I am creating a TCP tunnel application for RDP connections, On Server-side: Redirecting RDP connections to tunnel-server, Then sending those data to Client-side which receives the data successfully. But what happens after that? I don't know!
I know it is easier if traffic was HTTP/HTTPS because you can parse the header to address and content then send back the result. You don't even need TCP or sockets but forwarding RDP is unclear for me.
How can i forward those traffics from client-side then sending the results back to server and mstsc (windows default RDP client)? My problem is with the concept, Should i send those RDP data to client then from client machine to port 3389? And this app is considered some sort of Socks Proxy i guess.
This is the structure of what i have done at the moment:
Similar threads that aren't answer to my issue:
RDP through TCP Proxy
How to create a simple proxy in C#?
C# Proxy using Sockets, how should I do this?
P.S. The type of programming language doesn't matter for me (Currently working with c# and python but newer languages are OK too), I just want to learn how it works conceptually with a simple pseudo-code or sample, All kind of explanations or examples are appreciated.
How connect to https://api.push.apple.com using http2 with persistent connection ?
Persistent connection is to avoid rapid connection and disconnection:
APNs treats rapid connection and disconnection as a denial-of-service attack
https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Chapters/APNsProviderAPI.html
Is writing a client in c using https://nghttp2.org the only solution?
(If that question should be ask in another StackExchange website, please do tell me)
Non-persistent connections are a relic of the past. They were used in HTTP/1.0, but HTTP/1.1 already moved to a model where the connections were persistent by default, and HTTP/2 (also being multiplexed) continues on that model of connections being persistent by default.
Independently on the language you are using to develop your applications, any HTTP/2 compliant client will, by default, use persistent connections.
You only need to use the HTTP/2 client library in a way that you don't explicitly close the connection after every request you make.
Typically these libraries employ a connection pool that keeps the connections open, typically until an idle timeout fires.
When your application makes HTTP requests, the library will pick an open connection and send the request. When the response arrives the library will not close the connection but instead put it back into the pool for the next usage.
Just study how the library you want to use allows you to make multiple requests without closing the connection.
I also met this question!
If the connection be idle for a long time (about 1 hour), then function poll catches no socket status changed. It always returns 0 even as on_frame_send_callback was invoked.
Is there anyone can figure out the problem?
I'm trying to write standard FTP server.
I wonder whether this scenario is correct or not?
1. On each request of clients, a thread manager makes thread for control connection.
2. When control connection thread receives PORT command, it establishes data connection(active open)
Is this usual solution? I wonder this since I have to create standard FTP server.
I would be happy if you answered JUST 'yes' or 'no'.
Thank you in advance.
Yes, FTP uses two connections, read the RFC http://www.ietf.org/rfc/rfc959.txt, the wikipedia article is a bit friendlier http://en.wikipedia.org/wiki/File_Transfer_Protocol but the RFC is the bible.
As far as threads go you will need a thread to listen for incoming connections, a thread to process the control connection and a thread to process the data connection. You could do it all with one thread by using asynchronous i/o using select.
That is to say, if I have a server listening on 127.0.0.1, and a TCP connection comes in, how can I determine the process id of the client?
Also if there isn't an API for this, where would I be able to extract the information from in a more hackish manner?
(The purpose of this is to modify a local HTTP proxy server to accept or deny requests based on the requesting process.)
Edit: palacsint's answer below led me to find this answer to a similar question which is just what's needed
netstat -a -o
prints it. I suppose they are on the same machine becase you are listening on 127.0.0.1.
The only way to do this is if the connecting process sends some sort of custom headers which contains identifier. This is due to the fact that the networking layer is completely separated from the application layer (hint: OSI MODEL. This way it is possible to write lower layers software without caring what happens above as long as the messages exchanged (read: networking packets) follow a pre-determined format (read: use the same protocol).
I'm using the MS Winsock control in VB6 and I want to understand things like
"when does the Server Close the
connection (triggering the
Winsock_Close() event), and a
related question:
How do you know
when all the data from a a Post has
been returned?
More info:
I should have mentioned: I've already read the MSDN description, etc., but it doesn't actually explain what's happening. E.g., it explains the the Close() event fires when the Server ends the connection but doesn't explain what would cause the connection to end and whether a broken connection would trigger a Close event, etc.
And none of the MSDN descriptions explain know when all the data has arrived. (I suspect it's the Close even firing).
You might want to try out the following walkthrough
tcp.oflameron.com/
You can find the complete code here
If you have any Qs in particular, plz ask here...
GoodLUCK!!
- CVS
Using the Winsock Control at http://msdn.microsoft.com/en-us/library/aa733709(VS.60).aspx
MSDN Search of "Winsock control" at http://social.msdn.microsoft.com/Search/en-US?query=Winsock+control&ac=8
Documentation Lacks
The documentation will not provide the information you are asking for. This is an ActiveX control that allows you to connect computers through TCP/IP protocol stacks.
The information you want applies to how these computer "talk" (the protocol). That totally depends on the server application and client application that are communicating. For instance, if I am connecting to the FTP Service of another computer, the server will not close the connection until I send the appropriate command or until the server detects an idle connection. On the other hand, some services will close the connection on any invalid command, especially SMTP Servers will tighten security.
You need to check out the documentation of the service you are connecting with. The documentation will tell you how to send commands, command format, response codes, how commands are acknowledge, and so on.
SAMPLE: VBFTP.EXE: Implementing FTP Using WinInet API from VB at http://support.microsoft.com/kb/175179