![]() The kernel value parameters aren't saved with these commands, and are reset to the default values on system reboot, thus make sure to place the commands on a system startup script such as /etc/rc.local. Increase the range of ephemeral ports by setting ip_local_port_range kernel value on /proc/sys/net/ipv4/ip_local_port_range, using the command echo "32768 65535" > /proc/sys/net/ipv4/ip_local_port_range, this will set the port range from 32768 to 65535. Reduce the TIME_WAIT by setting the tcp_fin_timeout kernel value on /proc/sys/net/ipv4/tcp_fin_timeout, using the command echo 30 > /proc/sys/net/ipv4/tcp_fin_timeout to set it to 30 seconds. Increase the range of ephemeral ports by setting the dynamicportrange to an higher value through the command netsh int ipv4 set dynamicportrange tcp start=32767 num= 32768, this will set the port range from 32768 to 65535. Reduce the TIME_WAIT by setting the TcpTimedWaitDelay TCP/IP parameter to 30 seconds on the windows registry key HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters, as a DWORD value. This will set the port range from 1024 to 32768. Increase the range of ephemeral ports by setting the MaxUserPort TCP/IP parameter to an higher value (like 32768), on the windows registry key HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters, as a DWORD value. Reduce the TIME_WAIT by setting the TcpTimedWaitDelay TCP/IP parameter to 30 seconds on the windows registry key HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters, as a DWORD value. Just follow the instructions below for the correspondent operating system. How can we do that? That's the easy part. We can reduce the time wait to it's minimum allowing a faster recycle of the ephemeral ports, and increase the maximum number of ephemeral ports on the system, improving even further their availability on the system. So how can we improve these parameters for better performance? So let me detail the default values on supported operating systems. Let's just call it RANGE EPHEMERAL PORTSĪs we would expect, these parameters can vary from operating system to operating system, and they can assume different default values as much the same. The maximum number of ephemeral ports that the system can use, from the total pool of 65535 available ports. The time that the ports is in "waiting" status since it was released from the application, and it's in fact released by the system for reuse. Basically, we can tune several TCP/IP stack parameters, but in this context, there are 2 that really make the different: However, these ephemeral ports do take their time to be completely released to the system, and on a highly loaded environment, where you have hundreds of fast requests per second, you may reach a status where all ephemeral ports are either in use, or " waiting" to be released to the system, and when this happens, the application server will not be able to use them for new connectionsīut there are ways to tune the TCP/IP stack to reduce the impact of this problem, allowing the system to take advantage of all resources at its disposal. In the context of a web server, these temporary ports will be used to handled web requests or send web reference requests, and after it's done, they will be released back to the operating system for reuse, allowing these ephemeral ports to be recycled and used by other applications or for other requests. Some ports are reserved and used by the system itself, others are bound by applications permanently (usually until the application terminates, like port 80 for Application Server, or port 3389 for remote desktop, or ports 12000-12004 to OutSystems Services), and there's a set of ports called " ephemeral ports" that will be used by applications as temporary ports. I'm talking about connection ports resources on the TCP/IP stack, because each connection will have a unique port to handle the requests, and these ports are finite: there's only 65535 available ports on the system. Web requests consume TCP/IP connections, and each connection is unique an uses resources on your system. In environments with a very high number of web requests per second, or with a high number of web services/references integrations, you might find that the application's performance is lower then what you would expect from that system, or even worse, the applications or web services stop responding completely or generate timeout errors, even though your system's resources (CPU, RAM or Network bandwidth) don't seem to be exhausted at all. Although the causes for such symptoms can vary, there's one scenario that can cause a complete lock of systems handling a very large number of web requests per second without any hint of what's going on: TCP/IP port exhaustion.
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