If the Listen All setting is set to "No", then the TCP Port and TCP Dynamic Port settings under the IPAll section will be ignored and the TCP Port, TCP Dynamic Port, and Enabled settings on the individual IP n sections will be used instead.Įach IP n section has an Enabled setting with a default value of "No" which causes SQL Server to ignore this IP address even if it has a port defined. If the Listen All setting on the Protocol tab is set to "Yes", then only TCP Port and TCP Dynamic Port values under the IPAll section will be used and individual IP n sections will be ignored in their entirety. However, the TCP/IP architecture permits a port scanner to query for open ports, so changing the port number isn't considered a robust security measure.įor more information about the default Windows firewall settings, and a description of the TCP ports that affect the Database Engine, Analysis Services, Reporting Services, and Integration Services, see Configure the Windows Firewall to Allow SQL Server Access. This might be helpful in some environments. When you connect to a named instance through a firewall, configure the Database Engine to listen on a specific port, so that the appropriate port can be opened in the firewall.īecause port 1433 is the known standard for SQL Server, some organizations specify that the SQL Server port number should be changed to enhance security. This means they select an available port when the SQL Server service is started. Named instances of the Database Engine and SQL Server Compact are configured for dynamic ports. If enabled, the default instance of the SQL Server Database Engine listens on TCP port 1433. To make Hyper-V (and Windows in general) use this new dynamic range you have to reboot your system.This article describes how to configure an instance of the SQL Server Database Engine to listen on a specific fixed port by using SQL Server Configuration Manager. Let's say your development is under and up to port 60000, you can issue the following command to restrict the dynamic port range out of it (you must have administrator privilegs): netsh int ipv4 set dynamic tcp start=60001 num=5534 You can instruct Windows to modify this range out of the conflicting area. The answer: Protocol tcp Dynamic Port Range To find the "Dynamic Port Range" you can issue the command: netsh int ipv4 show dynamicport tcp This becomes a pain, because if you are developing an application or larger solution that uses multiple ports, some times you get a conflict and some times not after rebooting your system. The most likely reason for this is Windows Hyper-V (Microsoft's hardware virtualization product) that reserves random port ranges (usually blocks of 100 ports). You get an output with a list of port ranges reserved: Protocol tcp Port Exclusion Ranges When you issue the command: netsh int ip show excludedportrange protocol=tcp We managed to contain this problem for the case where you can not change your port numbers (like a non configurable application). Set the Windows "Dynamic Port Range" in a non conflicting place Meanwhile "netstat -ano" shows that there are exactly 5 ports in use in that range. What I discovered is that between the ranges of 30, there are 624 ports which are blocked. Listen on 3005 failed: The process cannot access the file because it is being used by another process Listen on 3004 failed: The process cannot access the file because it is being used by another process Listen on 3003 failed: The process cannot access the file because it is being used by another process Listen on 3002 failed: The process cannot access the file because it is being used by another process Listen on 3001 failed: The process cannot access the file because it is being used by another process Listen on 3000 failed: The process cannot access the file because it is being used by another process The program produced output similar to this. System.IO.Stream output = response.OutputStream ![]() Response.ContentLength64 = buffer.Length Get a response stream and write the response to it. int port = 3000 īyte buffer = 8.GetBytes(responseString) ![]() I wrote a program to listen on the ports between 30 inclusive on 127.0.0.1. ![]() I turned off the firewall and I have only Windows Defender AV. ![]() What I have found is that there are large number of ports blocked which are not tied to processes. This one is typical: Node.js Port 3000 already in use but it actually isn't?Īll the respondents of this question and similar questions all suggest using "netstat -ano" to find the process which is using the port and killing it. I found a number of questions on this topic. I discovered this problem trying to run a node server which used port 3000. What I have discovered is that there are a number of ports on my Windows 10 box which (1) are not in use by any process and (2) I cannot listen on.
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