How to Configure a Proxy Server in Firefox

If you want to send your web browser traffic—and only your browser traffic—through a proxy, Mozilla Firefox is a great option. It uses your system-wide proxy settings by default, but you can configure separate proxy settings for Firefox only.

RELATED: What’s the Difference Between a VPN and a Proxy?

Generally, you’ll use a proxy if your school or work provides it to you. You could also use a proxy to hide your IP address or access geoblocked websites that aren’t available in your country, but we recommend a VPN for that instead. If you need to set up a proxy for school or work, get the necessary credentials from them and read on.

Firefox is unique here because Chrome, Edge, and Internet Explorer don’t allow you to set a custom proxy server. They only use your system-wide proxy settings. With Firefox, you can route only some web traffic through the proxy without using it for every application on your system.

To access proxy settings in Mozilla Firefox, click on Firefox’s menu and go to Options.

Click the “Advanced” icon at the left side of the Preferences window, click the “Network” tab at the top of the window, and then click the “Settings” button under Connection.

You can select four different proxy options here. By default, Firefox is set to “Use system proxy settings”.

  • No proxy: Firefox won’t use a proxy server, even if one is configured in your system-wide proxy settings.
  • Auto-detect proxy settings for this network: Firefox will use the Web Proxy Auto-Discovery Protocol, also known as WPAD, to detect the appropriate proxy for your network. This feature is sometimes used only on business and educational networks to automatically provide the necessary proxy settings to all PCs on a network.
  • Use system proxy settings: Firefox follows whatever proxy settings you have configured in your system settings. If you don’t have a system-wide proxy configured, Firefox won’t use a proxy.
  • Manual proxy configuration: Firefox allows you to manually set custom proxy settings that will only be used for Firefox itself.

If you select “Manual proxy configuration”, you’ll need to enter your proxy server settings in the boxes here. Your proxy service provider—or employer, if it’s provided by your employer—will be able to provide the settings you need.

Enter the address of the proxy server you want to use for normal, unencrypted HTTP browsing connections in the “HTTP Proxy” box. You’ll also need to enter the port the proxy server uses in the “Port” box.

You’ll usually want to click the “Use the proxy server for all protocols” option. Firefox will also use your HTTP proxy server for SSL-encrypted HTTPS connections and File Transfer Protocol (FTP) connections.

Uncheck this box if you want to enter separate proxy servers for HTTP, HTTPS, and FTP connections. This isn’t common.

If you’re configuring a SOCKS proxy, leave the HTTP Proxy, SSL Proxy, and FTP Proxy boxes empty. Enter the address of the SOCKS proxy into the “SOCKS Host” and its port into the “Port” box.

RELATED: How to Use SSH Tunneling to Access Restricted Servers and Browse Securely

When you’re hosting a SOCKS proxy on your local PC, you’ll need to enter 127.0.0.1 and the port the SOCKS proxy is listening on. For example, you’ll need to do this if you create an SSH tunnel using dynamic port forwarding and want to send your browsing traffic through it. Firefox will send your browsing activity through the proxy server running on your local computer.

By default, Firefox uses SOCKS v5 for the connection. Select SOCKS v4 if your SOCKS proxy uses the older standard instead. If you’re not sure, leave the option set to SOCKS v5.

Firefox also allows you to provide a list of addresses that it will bypass the proxy for. Enter these in the “No Proxy for” box. By default, the list here includes localhost and 127.0.0.1 . These addresses both point to your local PC itself. When you attempt to access a web server running on your PC, Firefox will access it directly rather than attempting to access the addresses through the proxy.

You can add other domain names and IP addresses to this list. Just separate each address in the list with a comma followed by a space. For example, if you want Firefox to access howtogeek.com directly instead of accessing howtogeek.com through the proxy, you’d add howtogeek.com to the end of the list like so:

localhost, 127.0.0.1, howtogeek.com

If Firefox can’t access the proxy sever you configure—for example, if the proxy server is down, if your Internet connection is down, or if you entered the details incorrectly—you’ll see an “Unable to find the proxy server” error message when you attempt to access a website.

You’ll need to go back into Firefox’s proxy server settings and either disable the proxy or fix your proxy settings to browse the web.

Chris Hoffman is a technology writer and all-around computer geek. He's as at home using the Linux terminal as he is digging into the Windows registry. Connect with him on Twitter.