Windows – What else does “netsh int ip reset” do

dhcpnetshnictcpipwindows

According to this KB article when you run the "netsh int ip reset" command, all it does is to reset the content of two registry keys:

SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\
SYSTEM\CurrentControlSet\Services\DHCP\Parameters\

but on my test system it appears to do more than that.

On a Windows Server 2012 R2 x64 machine, after my application does something wrong, if I try to set up a static IP to a network interface I get instant BSOD.

To fix the issue I have to run "netsh int ip reset" and then I can set a static IP. Now, I'm trying to figure it out how does "netsh int ip reset" fix the problem.

I know is not the content of those 2 registry keys because I did the following on my virtual machine:

  • Make a VM backup when the system is troubled.
  • Launch the VM and run the "netsh int ip reset" command
  • Export the two registry keys
  • Roll back to the backup made before the "netsh int ip reset" command
  • Import the saved registries keys
  • Set up a static IP on an network interface, but I still get a BSOD

When my application tries to configure a network interface with an IP address that was already used by another network interface in the past, first it has to remove that IP configuration for the non-present device and then it can use that IP.

To do that it searches in every registry in SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces and sees if any of the interfaces did use the IP address I want to use by comparing the value in "IPAddress" property with the one I want to use.
If it finds a match, first it checks if that interface is live, and if it's not, it deletes the value in "IPAddress" property and set property "EnableDHCP" to 1, then I can use that IP on my interface.
This is what my application did wrong. When this interface comes back live again, it will set an IP configuration through DHCP, but it will BSOD if you try to set a static IP on it.
The correct way to do it is to set "IPAddress" property to "0.0.0.0" and "EnableDHCP" to 1. If you leave "IPAddress" empty and set "EnableDHCP" to 1, something goes wrong in TCPIP configuration, that "netsh int ip reset" will fix .. but what exactly it fixes, I have no idea. All I know it's that it's not in the two registries keys that the KB article mentions.

So what else does "netsh int ip reset" do, except resetting the content of those two registries, that fixes the problem on my test system?

Best Answer

That same KB article mentions that running the command will save a resetlog.txt log file. What does that log say?

You can also run Process Monitor from SysInternals and have it monitor your netsh command.

I did this on my Windows 8.1 workstation, filtering ProcMon's output by "process name > contains > netsh" and pulled over 5,000 results. Looks like there's a LOT going on when you run this command. I'm sorry, but I'm not going to parse all of that output for you :)

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