I saw some other mentions online regarding expanding the port range down to as low as 1024 (common, standardized applications originate at the 0-1023 port range). As more connections are open, and left waiting, the available pool of these randomly-assigned ports drops: eventually to the point you can't RDP to reboot the affected server. The "ephemeral port range" on modern systems is ports 49152 to 65535: and this is implemented separately for TCP, UDP, v4, and v6 (technically meaning you could have ~64000 open connects using all protocols). Basically, when you make a request to a service on a port (say 143 for email) the server will reply back to the client using a different port number (say 50000). Both articles referred to behavior on Windows to limit the number of ephemeral ports on a system. Another Microsoft post suggested using netstat to trace how many TCP/IP ports are open at a time. She used Process Explorer to diagnose instances occurring with software but no immediate fixes. Brand new file-server, with 50-100 possible users: maybe two weeks.Įarlier today, I had found an article from a Microsoft blogger regarding this behavior. Email and limited DNS service on one that server can die within 4-5 days uptime, and used to be able to run for weeks as a 2008R2 VM. Two servers I recently instituted with 2012, have become unresponsive after varying amounts of uptime. This issue can impact any networked system of note, but it seems particularly insidious on Windows servers. Since I didn't want to be some "blogospammer", I'm posting my findings here the original with hyperlink references Opens a new window is available. ![]() I did some digging, and figured out there's some "port exhaustion" going on, and did a writeup on it. ![]() ![]() But I think that will only move the problem for a few days.I was digging into some issues I've had with 2012 Server going crazy after varying amounts of uptime. I could lower the wait timeout to close them earlier or increase the number of outgoing connections (currently ~ 16000). Windows Defender is running on this server and additionaly I did a scan with Panda Antivirus. It looks like netstat is wrong, and the connections belong to another process. But FireFox, Explorer.exe and more than 10 other processes do not access this DB. A Postgres DB runs on 5432 on this server. The second strange thing is that 90% of these connections point to 192.168.24.10:5432. I captured Firefox.exe, SSHd, Windows Telemetry Service and many other processes with a huge list of wait connections. In this example the process seems to be explorer.exe but if I run the same command a few minutes later the open process is a different one. There were a huge list (> 1000) of connections in WAIT state. This is a very short list of connections in WAIT state. That looked like a typical handle / socket leak for me and I tried to find the process with "netstat -anobq" to which the connections can be assigned. ![]() To minimize the risk of data corruption, the TCP / IP standard requires a minimum time period to elapse between successive connections from a given local endpoint to a given remote endpoint ". This error typically occurs when outgoing connections are opened and closed at a high rate, causing all available local ports to be used and forcing TCP / IP to reuse a local port for an outgoing connection. "TCP / IP failed to establish an outgoing connection because the selected local endpoint was recently used to connect to the same remote endpoint. "A request to allocate an ephemeral port number from the global TCP port space has failed due to all such ports being in use". If this happens you will find these warnings in the Windows Eventlog: I am investigating a network problem on a Windows Server 2016.Īround once a week, all outgoing ports are used up, which means that various network components no longer function properly.
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