In TCP there is only one way to detect an orderly disconnect, and that is by getting zero as a return value from read()/recv()/recvXXX() when reading. There is also only one reliable way to detect a broken connection: by writing to it. After enough writes to a broken connection, TCP will have done enough retries … Read more
A single listening port can accept more than one connection simultaneously. There is a ’64K’ limit that is often cited, but that is per client per server port, and needs clarifying. Each TCP/IP packet has basically four fields for addressing. These are: source_ip source_port destination_ip destination_port <—– client ——> <——— server ————> Inside the TCP … Read more
For my suggestion, please read the last section: “When to use SO_LINGER with timeout 0”. Before we come to that a little lecture about: Normal TCP termination TIME_WAIT FIN, ACK and RST Normal TCP termination The normal TCP termination sequence looks like this (simplified): We have two peers: A and B A calls close() A … Read more
On macOS Big Sur and later, use this command: sudo lsof -i -P | grep LISTEN | grep :$PORT or to just see just IPv4: sudo lsof -nP -i4TCP:$PORT | grep LISTEN On older versions, use one of the following forms: sudo lsof -nP -iTCP:$PORT | grep LISTEN sudo lsof -nP -i:$PORT | grep LISTEN … Read more
Since there are no events available to signal when the socket is disconnected, you will have to poll it at a frequency that is acceptable to you. Using this extension method, you can have a reliable method to detect if a socket is disconnected. static class SocketExtensions { public static bool IsConnected(this Socket socket) { … Read more
The answer differs depending on what OS is being considered. In general though: For TCP, no. You can only have one application listening on the same port at one time. Now if you had 2 network cards, you could have one application listen on the first IP and the second one on the second IP … Read more
It’s fatal. The remote server has sent you a RST packet, which indicates an immediate dropping of the connection, rather than the usual handshake. This bypasses the normal half-closed state transition. I like this description: “Connection reset by peer” is the TCP/IP equivalent of slamming the phone back on the hook. It’s more polite than … Read more
You might have guessed it already: it’s a connection error. “ECONNRESET” means the other side of the TCP conversation abruptly closed its end of the connection. This is most probably due to one or more application protocol errors. You could look at the API server logs to see if it complains about something. But since … Read more
This exception means that there is no service listening on the IP/port you are trying to connect to: You are trying to connect to the wrong IP/Host or port. You have not started your server. Your server is not listening for connections. On Windows servers, the listen backlog queue is full.
How can I connect to Android with ADB over TCP? [closed]