The problem
Six clicks deep, in four different windows.
Change a fixed IP on Windows and you land in a dialog box that has not been redesigned in twenty years, reached through a control panel that redirects to a settings app that sends you back to the control panel. Check whether the firewall is blocking that interface and you are somewhere else entirely. Ask whether the network actually works and nothing tells you: you open a terminal and ping something.
On a live event that is the sequence you run through with a room waiting. Switch the machine from the production network to the venue network, confirm the interface came up, confirm nothing is being blocked. Every second of it visible to everybody.
And the worst case is the one nobody warns you about: you type a static address on a remote machine, press apply, and lose the link to the machine you were configuring.
The answer
One window. Or no window at all.
NetCatChanger lists every network adapter with its addressing mode, its gateway and its current profile, and puts a single labeled switch on each card. Public on one side, Private on the other, the knob sitting on the current state. One click flips it and it applies immediately, with a toast offering to undo rather than a dialog blocking the way. The old confirmation prompt is still there in Settings if you prefer it.
It also lives in the notification area. Right-click the tray icon and switch any interface without opening the window at all. The close button minimizes to the tray instead of quitting, and the app can start with Windows and stay hidden there.
Safe by default
A wrong IP no longer costs you the machine.
Each adapter card has an IP button: switch between DHCP and a static configuration, address, mask, gateway and DNS, and save any of it as a named preset to re-apply in one click.
Because a wrong static address cuts you off from the machine you are configuring, every change is guarded. Once applied, a dialog counts down fifteen seconds. Confirm and the configuration stays. Say nothing, because you can no longer reach the machine, and the previous configuration comes back on its own.
The firewall
Off for ten minutes, not off until you remember.
Turning the firewall off is no longer all or nothing. Disable only the profiles currently active or all of them, and choose how long: ten minutes, one hour, or until you turn it back on yourself. The timed options re-enable it without you.
If the app quits while a timer is still running, the firewall is re-enabled on the way out. The machine is never left unprotected because somebody closed a window.
Diagnostics
It tells you whether the network works.
Every connected interface shows whether its gateway answers. The header shows whether DNS resolves and whether the internet is reachable. An interface stuck on a 169.254 address, which means the DHCP server never answered, is flagged in red instead of being displayed as a perfectly normal IP.
The list shows every adapter, including the disconnected and the disabled ones, with the connected interfaces first. Adapters are enabled, disabled and renamed from their own card, DHCP leases renewed per interface, and one button flushes the resolver cache.
What is in it
The rest of the toolbox.
Labeled profile switch
Public and Private on one switch per card, the knob sitting on the current state. It applies immediately, with an Undo toast instead of a blocking dialog.
Tray icon
Switch any interface from the notification area without opening the window. Close minimizes to the tray rather than quitting, and it can start hidden with Windows.
IP presets
DHCP or static with address, mask, gateway and DNS, saved as named presets and re-applied in one click.
Automatic rollback
Fifteen seconds to confirm a new address. No confirmation means the previous configuration is restored on its own.
Timed firewall disable
Active profiles or all of them, for ten minutes, one hour, or until you say otherwise. Re-enabled automatically, and on exit if a timer is still pending.
Read-only mode
Decline the elevation prompt and the app does not close and does not pretend. It starts read-only, shows everything, changes nothing, and offers to restart elevated.
Launch with Windows
Registered as a scheduled task with highest privileges, which is the only way an elevated app can actually start at logon without a UAC prompt every boot.
Live diagnostics
Gateway response per interface, DNS resolution and internet reachability in the header, and a red flag on any interface stranded on 169.254.
Every adapter listed
Connected, disconnected and disabled, sorted with the live ones first. Enable, disable and rename from the card, renew a DHCP lease per interface, flush the resolver cache in one click.
Installer and portable
A standard Windows installer with Program Files, a Start menu entry, an optional desktop icon and a clean uninstaller, plus the portable executable for machines you are not allowed to modify.
Session log and settings
Every change, profile, firewall, IP or adapter, written to a session log you can open from the footer. Window size and position remembered.
Sharp on HiDPI
Per-monitor DPI awareness, so nothing is blurry at 125, 150 or 200 percent.
Settings live in %APPDATA%\NetCatChanger and deliberately survive an uninstall and reinstall. On launch the app checks this repository for a newer version and shows a small dismissible notice at most once per version. Nothing else is sent anywhere.
Open source, properly
Credited down to the icons.
The adapter and firewall icons are Lucide, taken verbatim from the lucide-static package, with only stroke colour and raster size changed. Lucide is ISC licensed, which is compatible with GPL v3 and asks only that the copyright notice travels with the icons.
The licence text and the exact list of icons used ship in the repository, the untouched source SVGs sit beside them, and the README, the About dialog and the installer all carry the same notices. The Poppins typeface is credited under the SIL Open Font Licence in the same place.
The icons used until now came from an unidentified set, exported with the metadata stripped and no record of their licence. Shipping them in a public GPL v3 repository was not defensible, so they are gone.
Free download