Firewall Software Download: Protect Your Network

A firewall inspects network packets and applies rules to allow or block them. Inbound filtering stops outside attempts to reach your machine, while outbound filtering controls which of your apps can phone home. Together they reduce your attack surface and can flag suspicious behavior, like an unexpected program trying to send data out.

A firewall does not detect viruses on its own; pair it with antivirus and a malware scanner for layered protection.

For most home users, the firewall built into the operating system provides strong inbound protection. Here is what each one offers, according to its maker:

• Windows: the Firewall and network protection page in the Windows Security app has separate domain, private and public network profiles; public networks such as cafe Wi-Fi get tighter restrictions. You can allow a blocked app or open a port, use Block all incoming connections (which ignores the allowed-apps list), or Restore firewalls to default. Microsoft warns that turning the firewall off could make your device more vulnerable and recommends allowing the specific app instead.
• macOS: the firewall is under System Settings, Network, Firewall. Its options include blocking all incoming connections, automatically allowing built-in and downloaded signed software, and stealth mode, which stops your Mac responding to probing requests.
• Ubuntu Linux: Ubuntu's security documentation says ufw, its simplified firewall tool, is available but disabled by default. It is a front end for iptables and nftables.

Third-party firewalls become worthwhile if you want detailed outbound control, real-time connection prompts, or a more visual way to manage rules.

Facts below are from each vendor's own page, checked in November 2026:

• ZoneAlarm Free Firewall offers two-way traffic monitoring and public and private network zones. Its page says it is compatible with Windows 11 and 10 and needs .NET Framework 3.5 or later.
• Comodo Firewall is offered as a free download, but its system requirements list Windows XP to Windows 10 and do not mention Windows 11, so check compatibility before installing it on a newer PC.
• GlassWire is a network monitor and firewall for Windows, with an Android app. It shows which hosts each app talks to, can block apps, and has an Ask to connect mode for new connections. It can be used free, with a Premium upgrade.
• LuLu from Objective-See is a free, open-source macOS firewall that blocks unknown outgoing connections. Version 4.5.7 needs macOS 10.15 or later. It does not filter incoming connections, so keep the built-in macOS firewall on as well.
• OPNsense and pfSense are open-source firewall platforms you run on a dedicated device, protecting the whole network rather than one computer.

Choose based on whether you want software on one computer or a firewall for the whole network.

Good firewall software offers clear per-application rules, both inbound and outbound control, logging so you can review blocked connections, and sensible default profiles for home and public networks. Network activity visualization helps non-experts understand what is happening, while a stealth mode hides your machine from casual scans.

Avoid tools that nag constantly or bundle unrelated "optimizers," which add clutter without real security value.

Security software is a prime target for impersonation, so download only from the official vendor: zonealarm.com, comodo.com, glasswire.com, objective-see.org for LuLu, and opnsense.org or pfsense.org for the platforms. Be skeptical of pop-ups claiming your PC is infected and offering a "firewall" download.

Check the publisher in the installer's digital signature and scan the file before running it. A new firewall can block apps you rely on, so set aside time to review its first prompts. If you think something malicious already got through, see our malware removal tool guide.

Most third-party Windows firewalls are designed to take over from the built-in one, while outbound-only tools such as LuLu on macOS sit alongside the system firewall. Running two full firewalls that both filter the same traffic tends to cause confusing blocks rather than extra protection. Follow the vendor's install notes, and if you remove a third-party firewall later, check that the Windows or macOS firewall is switched back on.