Comodo Firewall controls which programs on a Windows machine may reach the network, hides your open ports from scanners, and runs anything it does not recognise in an isolated container instead of letting it touch the real system. It is free, including for business use, and it has been one of the better-known alternatives to the built-in Windows firewall for years.
Two things to weigh before deploying it. The most recent release announcement is from December 2024 (version 12.3.4.8162), and the vendor’s own system requirements still stop at Windows 10 — Windows 11 is not listed.
Comodo Firewall at a glance
| Latest announced version | 12.3.4.8162, announced December 2024 |
|---|---|
| Licence | Free, including business use |
| Stated system requirements | Windows XP through Windows 10, 32- and 64-bit; about 150 MB RAM and 400 MB disk |
| Windows 11 | Not listed in the vendor’s requirements |
| Development pace | Slow — no newer release announcement since December 2024 |
How it works
The design principle is “default deny”: anything that is not on the known-good list does not simply run. In practice that means three mechanisms working together.
- Application-level firewall — rules for inbound and outbound connections per program, with alerts when something behaves unexpectedly.
- Containment (auto-sandbox) — an unknown program runs against a virtual file system and registry, so it cannot modify the real ones.
- HIPS — behaviour monitoring, with a training mode that learns which applications you trust and writes the rules for you.
Around these sit port stealthing (your machine does not answer scans at all), cloud lookups against a large whitelist of known applications, a game mode that stops alerts during full-screen use, and a virtual desktop for opening things you do not trust.
Download and install
- Click the Download button at the top of this page and unpack the archive.
- Run the installer with administrator rights. Read the component list carefully — the installer is shared with the full Comodo Internet Security suite and offers extra components you may not want.
- Reboot when asked: the firewall installs kernel drivers.
- Run in training mode for the first days so it learns the applications you actually use, then switch to normal mode.
- Check the containment settings. Aggressive containment is what protects you, and also what breaks an unusual in-house application.
Where it fits, and where it does not
Good fit: a workstation that needs stronger outbound control and sandboxing than Windows provides, where somebody is willing to answer the prompts during the learning period.
Poor fit:
- Windows 11 machines — the vendor does not claim support.
- Central management across many PCs; that is the paid endpoint product.
- Users who will click through alerts without reading them. A default-deny firewall answered carelessly is worse than none.
- Anyone who needs regular security updates — the release pace suggests the product is largely dormant.
Known issues documented by the vendor
| Problem | Detail |
|---|---|
| KillSwitch component fails to install | Reported for 12.3.4.8162 as a corrupted-package error. |
| Virtual desktop and containment problems | Reported in the same build on the official forum. |
| Revoked signing certificate | An advisory was published in October 2024 with a workaround. |
| Throughput reduced | Users report slower transfers with the firewall active — test before rolling out. |
| Extra components installed | The installer offers browser and homepage changes; deselect what you do not want. |
Comodo Firewall vs. alternatives
| Tool | How it compares |
|---|---|
| SimpleWall | Free, open source, tiny; blocks outbound traffic without sandboxing or HIPS |
| GlassWire | Excellent monitoring and history; blocking requires the paid tier |
| Portmaster | Open source and actively developed, combines monitoring, blocking and DNS filtering |
| Windows Defender Firewall | Built in and well maintained; outbound rules exist but there are no prompts and no sandbox |
FAQ
Is Comodo Firewall free for business use?
Yes. The vendor’s FAQ states it is free for business users too, and points larger networks at its paid centrally managed product.
Does it work on Windows 11?
The official requirements list Windows XP through Windows 10. Windows 11 is not mentioned, so treat that combination as unsupported.
Is it still being updated?
The last release announcement is from December 2024, and the product pages still carry 2019 branding. Development appears to have slowed considerably.
Does it include antivirus?
The firewall alone does not. Antivirus is part of the fuller Comodo Internet Security package.
Why do I get so many alerts at first?
By design — it does not trust what it has not seen. Use training mode for the first days so it builds rules from your normal work.
Can it manage many computers centrally?
No, that requires the paid endpoint product.
