Solidworks Host File Block Guide

While the temptation to resolve a nagging error by editing a single text file is strong, the potential consequences for a business or an individual professional are extremely severe. Understanding these risks is critical before taking any action.

Ensure your corporate firewall explicitly permits bidirectional traffic to standard activation endpoints, preventing automated security systems from accidentally auto-blocking SolidWorks traffic.

Before diving into SolidWorks specifically, you need to understand the hosts file. It is a plain text file present in every operating system (Windows, macOS, Linux) that maps hostnames to IP addresses.

Unofficial or pirated copies of SolidWorks use hosts file modifications to prevent the software from phone-home validation checks. When clean, licensed instances are later installed on that same machine, the leftover blocks cause genuine activations to fail. Symptoms of a SolidWorks Host File Block Solidworks Host File Block

The SolidWorks Host File Block can occur due to various reasons, including:

| Issue | Legitimate Solution | | :--- | :--- | | | Edit Hosts File Temporarily: This is the one proper use case. Add the correct server IP and hostname to the hosts file as a temporary fix while you resolve the underlying DNS issue. | | Need granular control over network licenses. | Use the OPT (Options) File: The SolidNetWork License Manager allows administrators to create a sw_d.opt file. This powerful tool can reserve licenses for specific users, deny access to certain versions, and manage license borrowing. | | Clients need to find a new license server. | Reconfigure the License Manager Client: On each client machine, launch the "SolidNetWork License Manager Client". Simply go to the Server List tab, remove the old server entry, and add the new one using the format port@hostname (e.g., 25734@new-license-server ). | | Client on a different subnet can't find server. | Use the Hosts File for Direct Mapping: As a permanent fix, the hosts file is a perfectly legitimate tool for manually defining the path to a server for specific clients when DNS is insufficient. |

# SolidWorks Block List 127.0.0.1 localhost 127.0.0.1 solidworks.com 127.0.0.1 www.solidworks.com 127.0.0.1 login.solidworks.com 127.0.0.1 activation.solidworks.com 127.0.0.1 license.std.3ds.com 127.0.0.1 std.3ds.com 127.0.0.1 events.3ds.com 127.0.0.1 swym.3ds.com While the temptation to resolve a nagging error

There are three primary scenarios where SolidWorks domains end up blocked in a local hosts file: 1. Security Software and Firewall Overreach

Open as an Administrator (Right-click Notepad -> Run as Administrator). Open the hosts file from the location above.

I can provide specific firewall rules or script deployment solutions based on your environment. Share public link Before diving into SolidWorks specifically, you need to

Users attempting to set up a local PDM server, as described by GoEngineer , may have inadvertently mistyped an entry, creating a block rather than a redirect.

If your organization utilizes genuine standalone commercial or educational licenses that require periodic online validation, blocking the activation servers will trigger validation errors, rendering the software unusable until the block is removed.

Users cannot successfully borrow or validate licenses from an external or hosted license manager because local traffic is being misrouted.

You cannot edit this file with standard user privileges.