Windows can't bind to port above 49690

Question

I've been running an application which binds to port 50005 for quite some time and it seems that something changed recently and no application on my machine is able to bind to any TCP port above 49690 .. on 127.0.0.1.

Does anyone know when / what changed?

OS Name Microsoft Windows 10 Enterprise
Version 10.0.17763 Build 17763

running psping I get "Error binding TCP socket: An attempt was made to access a socket in a way forbidden by its access permissions." — Warrick FitzGerald, Jan 14 '19 at 12:25
Are you running as administrator, if not: can you test that. — Lieven Keersmaekers, Jan 14 '19 at 12:26
What's interesting is that I can bind to much higher port like 50583 .. but anything between 49691 and 50005 seems to fail and when looking at the current bindings there's nothing bound to those ports. — Warrick FitzGerald, Jan 14 '19 at 12:28
netstat -ano | find ":50005" does not return anything - looking in TCPView and netstat does not show anything bound to that port. https://stackoverflow.com/questions/113224/what-is-the-largest-tcp-ip-network-port-number-allowable-for-ipv4 ... seems to suggest that ... the range is Dynamic/private ports: 49152 to 65535 — Warrick FitzGerald, Jan 14 '19 at 12:35
https://support.microsoft.com/en-za/help/929851/the-default-dynamic-port-range-for-tcp-ip-has-changed-in-windows-vista — Warrick FitzGerald, Jan 14 '19 at 12:38
netsh int ipv4 show dynamicport tcp Protocol tcp Dynamic Port Range --------------------------------- Start Port : 49152 Number of Ports : 16384 — Warrick FitzGerald, Jan 14 '19 at 12:39
so I think that becasue the dynamic range has changed it's possible that something is using that port for a client connection, not a bound listing connection ... not 100% sure though yet. — Warrick FitzGerald, Jan 14 '19 at 12:40
That should also have been in the output of `netstat`. You can start a wireshark trace or attach procdump to get a dump of the exception or start medling with procmon but chances ar'e that a mere reboot will suffice. — Lieven Keersmaekers, Jan 14 '19 at 12:43
Yes, I suspect you're correct that a reboot will fix it. Until next time .. I'm going to dig deeper as I also would have expected netstat to show something using that port. — Warrick FitzGerald, Jan 14 '19 at 12:46
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/186654/discussion-between-lieven-keersmaekers-and-warrick-fitzgerald). — Lieven Keersmaekers, Jan 14 '19 at 12:48

score 7 · Answer 1 · answered Jan 14 '19 at 14:48

The problem was related to this: https://support.microsoft.com/en-za/help/929851/the-default-dynamic-port-range-for-tcp-ip-has-changed-in-windows-vista

It seems the Windows reserves the bottom range of these dynamic ports. The only way I could free up the port, allowing any application to bind to port 50005 was to move the dynamic port range up a little.

After the below change and a reboot all applications were once again able to bind to the port.

score 6 · Answer 2 · answered Jan 14 '19 at 19:01

6

It turned out the real problem was Docker.

netsh int ip show excludedportrange protocol=tcp

netsh int ip add excludedportrange protocol=tcp startport=50005 numberofports=2

answered Jan 14 '19 at 19:01

Warrick FitzGerald

1,583
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how do you know it's the docker? running that command does not give any information about what is holding those ports etc? – ANewGuyInTown Jul 15 '20 at 07:55

score 0 · Answer 3 · answered May 20 '21 at 03:25

https://answers.microsoft.com/zh-hans/windows/forum/windows_10-networking/%E7%AB%AF%E5%8F%A3%E8%A2%AB%E5%8D%A0%E7%94%A8/14a7fecd-1b6e-4728-813c-d6077ea23dc5

https://github.com/docker/for-win/issues/3171

netsh int ipv4 show excludedportrange protocol=tcp

netsh int ip delete excludedportrange protocol=tcp startport=50005 numberofports=100

Windows can't bind to port above 49690

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