The COM Guides

Configure and remove a proxy in Firefox

Where Firefox keeps its proxy controls, what each mode means, and how to test and undo a manual configuration.

Written byProx Editorial

Published

Reading time2 min

Prox guide

What you need

Have the proxy hostname or IP address, port, protocol, and any required username and password ready. Only use credentials supplied by the service owner; never reuse an important password.

Open Connection Settings

  1. Open Firefox and select the menu button.
  2. Choose Settings.
  3. In General, find Network Settings and select Settings or Configure proxy. The exact label can vary slightly by Firefox release.
  4. Note the current selection before changing it.

Mozilla maintains the authoritative Firefox Connection Settings instructions.

Choose the right mode

  • No proxy connects Firefox directly.
  • Use system proxy settings follows Windows, macOS, or Linux configuration.
  • Manual proxy configuration accepts explicit HTTP, HTTPS, and SOCKS endpoints.
  • Automatic proxy configuration URL loads rules from a PAC file supplied by an administrator or trusted provider.

For a manual HTTP endpoint, enter its address and port in the HTTP field. Only select the option to use it for HTTPS when the provider says that configuration is supported. For SOCKS, choose SOCKS v5 when the service specifies SOCKS5. If Firefox offers remote DNS for SOCKS5, enabling it can reduce local DNS leakage, but it does not make an untrusted endpoint trustworthy.

Test the result

Use a private window and visit a known HTTPS IP-check service. Confirm that the public address changed, then browse a non-sensitive HTTPS page. A working page alone does not prove that the proxy is safe.

If Firefox asks for proxy authentication, check the hostname before entering credentials. Stop if the certificate, hostname, or prompt is unexpected.

Turn the proxy off

Return to Connection Settings and restore the original option, normally Use system proxy settings or No proxy. Close private windows and verify that your ordinary public address has returned.

Firefox may show when an extension controls the connection. Remove or disable an extension you do not recognise instead of fighting its settings. Avoid random “free proxy” extensions: an extension can gain much broader browser access than a simple proxy configuration.