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.
The absolute limitation on TCP packet size is 64K (65535 bytes), but in practicality this is far larger than the size of any packet you will see, because the lower layers (e.g. ethernet) have lower packet sizes. The MTU (Maximum Transmission Unit) for Ethernet, for instance, is 1500 bytes. Some types of networks (like Token … Read more
It is true that a typical IPv4 header is 20 bytes, and the UDP header is 8 bytes. However it is possible to include IP options which can increase the size of the IP header to as much as 60 bytes. In addition, sometimes it is necessary for intermediate nodes to encapsulate datagrams inside of … Read more
This is explained in Beej’s networking guide. shutdown is a flexible way to block communication in one or both directions. When the second parameter is SHUT_RDWR, it will block both sending and receiving (like close). However, close is the way to actually destroy a socket. With shutdown, you will still be able to receive pending … Read more
Maximum number of connections are impacted by certain limits on both client & server sides, albeit a little differently. On the client side: Increase the ephermal port range, and decrease the tcp_fin_timeout To find out the default values: sysctl net.ipv4.ip_local_port_range sysctl net.ipv4.tcp_fin_timeout The ephermal port range defines the maximum number of outbound sockets a host … Read more
If you know what port the process is running you can type: lsof -i:<port>. For instance, lsof -i:8080, to list the process (pid) running on port 8080. Then kill the process with kill <pid>
On Linux, see netem: the kernel already contains support for traffic shaping, and can simulate high latency, low bandwidth, packet losses, and all sort of other adverse conditions, even on a loopback device (so you don’t need a real, physical network to test across).
This method checks whether mobile is connected to internet and returns true if connected: private boolean isNetworkConnected() { ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); return cm.getActiveNetworkInfo() != null && cm.getActiveNetworkInfo().isConnected(); } in manifest, <uses-permission android:name=”android.permission.ACCESS_WIFI_STATE” /> <uses-permission android:name=”android.permission.ACCESS_NETWORK_STATE” /> Edit: This method actually checks if device is connected to internet(There is a possibility it’s connected to … Read more
It’s 99th percentile. It means that 99% of the requests should be faster than given latency. In other words only 1% of the requests are allowed to be slower.
NetHogs is probably what you’re looking for: a small ‘net top’ tool. Instead of breaking the traffic down per protocol or per subnet, like most tools do, it groups bandwidth by process. NetHogs does not rely on a special kernel module to be loaded. If there’s suddenly a lot of network traffic, you can fire … Read more