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How to Set Up a Proxy in Firefox: Connection Settings, a Login and SOCKS5

How to set a proxy in Firefox, step by step: the Connection Settings window, which fields to fill for HTTP and for SOCKS5, what happens with a username and password, and how to check and switch it off.

What this guide rests on

The steps follow Mozilla's support page "Connection settings in Firefox" (last updated 16 December 2024 on the page). On 2 November 2026 the live page showed only a browser check, so I read it through an Internet Archive copy of the same URL. That page names the menu path, the five choices in the window, the "Also use this proxy for HTTPS" box and the "No Proxy For" list. It does not describe SOCKS fields, Proxy DNS or the login prompt. For those I used Mozilla's policy reference for administrators, whose proxy options "correspond to the connection settings in Firefox preferences"; it is not a user guide, so if a label on your screen differs, trust the screen.

Three words explained

A proxy is another computer that sends your requests to the internet for you; websites then see the proxy's address instead of yours.

HOST and PORT are the address of that computer and the number of its door. USERNAME and PASSWORD prove that you may use it.

SOCKS5 is a second kind of proxy besides HTTP. It passes data along without reading web addresses.

Open the proxy window

  1. Open Settings

    Click the menu button (three lines) in the top-right corner and choose Settings. On macOS you can also click Firefox in the menu bar and choose Settings (older macOS versions call it Preferences).

  2. Find Network Settings

    In the General panel go to the Network Settings section and click Settings. The Connection Settings dialog opens.

The choices in the window

Mozilla's support page lists five choices in the window: No proxy; Auto-detect proxy settings for this network; Use system proxy settings (the proxy configured for your operating system); Manual proxy configuration, where each proxy needs a hostname and a port number; and Automatic proxy configuration URL, for a .pac file (a small script that decides which address goes through which proxy). For a Proxy302 IP choose Manual proxy configuration. If you choose Use system proxy settings, Firefox does not use its own fields, and the system proxy guide applies instead.

Manual setup with an HTTP proxy

  1. Choose Manual proxy configuration

    Select it so that the address fields can be filled in.

  2. Fill in the proxy address

    Type HOST in the HTTP Proxy box and PORT in the Port box.

  3. Use the same proxy for HTTPS

    Mozilla's page says: if the same proxy name and port are used for all protocols, tick "Also use this proxy for HTTPS". Websites with https:// go through an HTTP proxy by a method called CONNECT, which MDN describes as the way a client behind an HTTP proxy reaches TLS sites.

  4. Click OK and open a page

    If the proxy asks for a login, Firefox shows a prompt; see the next section. The Mozilla pages I read do not show what that prompt looks like.

Username and password

Mozilla's policy reference lists proxy options for the addresses, the SOCKS version, hosts that skip the proxy and DNS, but none for a username or password, and an AutoLogin option described as "do not prompt for authentication if password is saved". So Firefox gets the login from a prompt, not from the window. A proxy that wants a login answers with code 407; MDN says the client may repeat the request with a new or replaced Proxy-Authorization header, which is what the prompt does for you. Type the USERNAME and PASSWORD from My assets there.

If the box keeps coming back, the proxy rejected the details: copy them again.

Manual setup with a SOCKS5 proxy

  1. Fill in the SOCKS proxy line

    In the manual configuration, type HOST and PORT in the line for the SOCKS proxy. Mozilla's policy reference calls it "the SOCKS proxy server" and takes the port after a colon; the support page I read does not describe this line, so use the label you see on screen.

  2. Choose version 5

    The policy reference says the SOCKS version can be 4 or 5. Pick SOCKS v5.

  3. Tick the proxy DNS option for SOCKS v5

    The policy reference describes it as "use proxy DNS when using SOCKS v5". DNS is the step where a name such as example.com is turned into a number; the option is meant to make that step go through the proxy instead of your local network. The Mozilla pages I read do not explain it further, and they do not say how Firefox handles a SOCKS5 login.

Addresses that skip the proxy

The window has a No Proxy For line. Mozilla's support page describes it as a list of hostnames or IP addresses that will not be proxied, and says <local> stands for all hostnames which do not contain periods. Add the addresses you want to reach directly.

How to check that the proxy works

  1. Open https://ipinfo.io/json in a new tab

    It shows the IP, country and network that websites see. Compare with the same page without the proxy.

  2. Test the proxy outside Firefox

    Run the curl command below. If it fails, the problem is the proxy details, not Firefox.

  3. Read the message Firefox shows

    A refused connection means the address or port is wrong or closed; a repeating login box means the details were rejected.

Check the proxy outside the browser: example

curl -x http://USERNAME:PASSWORD@HOST:PORT https://ipinfo.io/json

Replace HOST, PORT, USERNAME and PASSWORD with the values from My assets.

Many proxies or a switch

If you move between several proxies, an extension that changes proxies from a button is easier; FoxyProxy has its own guide. To switch the proxy off, open the same window and choose No proxy.

Common errors

• The proxy server is refusing connections. The address or port is wrong, or the proxy is not listening. Copy HOST and PORT again.

• The login box keeps coming back or the page says 407. Copy the username and password again.

• The IP did not change. Use system proxy settings is chosen and the computer has none, or an extension controls Firefox's connection: Mozilla's page says the dialog then shows the extension and a Disable Extension button.

• Sites do not open with SOCKS5. Check that the version is 5 and that HOST and PORT are in the SOCKS proxy line, not in the HTTP Proxy line.

How to do it with Proxy302

A static ISP proxy fits when you want one permanent address for your browser: the IP stays the same for the whole lease and you choose the protocol at purchase. Choose HTTP for the simplest set-up: one address line and a login prompt. If you bought SOCKS5 (port 3333), use the SOCKS lines above, keeping in mind that Mozilla's pages do not describe a SOCKS5 login. The product itself is described on the static residential proxies page.

How to do it with Proxy302: steps

  1. Step 1

    Open the static ISP page, choose the country, set Protocol to HTTP, choose the term and the quantity, then review the cost and generate.

  2. Step 2

    Open My assets and copy HOST, PORT, USERNAME and PASSWORD. The Connect page shows a ready example with your own details. HTTP uses port 2222 on proxy.proxy302.com.

  3. Step 3

    Put the values into the Firefox Connection Settings as shown above (HTTP Proxy line for an HTTP IP, SOCKS Host line for a SOCKS5 IP) and click OK.

  4. Step 4

    Check the exit with the curl command above and read the country and org fields, as the proxy location guide explains.

Prices and limits

A static ISP IP costs US$0.50 for one day and US$7.99 for 30 days, about US$0.27 per day, the same in every country. Availability by country changes daily and is shown on the order page. There is no free trial, and the smallest purchase is one IP for one day.

FAQ

Does Firefox use the computer's proxy?

Only if you choose Use system proxy settings. Otherwise Firefox uses the fields in its own Connection Settings window.

Where do I type the username and password in Firefox?

Not in the window. The proxy options have no such field; Firefox asks in a prompt when the proxy answers that a login is needed.

What does Proxy DNS when using SOCKS v5 do?

Mozilla's policy reference calls it "use proxy DNS when using SOCKS v5". It is meant to send name lookups through the SOCKS proxy instead of your local network; tick it when you use SOCKS5.

How do I switch the proxy off?

Open Connection Settings again and choose No proxy.

Reference links

5
  1. Mozilla Support: Connection settings in Firefox

    Official documentation · Confirmed on:

    Support page "Connection settings in Firefox", last updated 16 December 2024 on the page. Opened on 2 November 2026 through an Internet Archive copy of the same URL (web.archive.org snapshot of 28 December 2025), because the live page returned only a browser check. Read: menu path (Settings, General, Network Settings, Settings...); the Connection Settings dialog; the choices No proxy, Auto-detect proxy settings for this network, Use system proxy settings, Manual proxy configuration (each proxy needs a hostname and a port), Automatic proxy configuration URL (.pac); the "Also use this proxy for HTTPS" box; No Proxy For (hostnames or IP addresses that will not be proxied, <local>); the note that the dialog shows extensions that control the connection, with a Disable Extension button.

    The page does not describe SOCKS fields, SOCKS version, proxy DNS or any login prompt. The archive copy may differ from the live page.

  2. Mozilla: Firefox policy templates, Proxy

    Official documentation · Confirmed on:

    Read on 2 November 2026 (Proxy policy section): the Proxy policy "corresponds to the connection settings in Firefox preferences"; fields for the mode, HTTP proxy, using the HTTP proxy for all protocols, SSL proxy, SOCKS proxy, SOCKS version (4 or 5), hosts that are not proxied (with <local>), a PAC address, AutoLogin ("do not prompt for authentication if password is saved") and proxy DNS when using SOCKS v5; no field for a username or password.

    It is an administrator reference, not a user guide, and it does not give the window's on-screen labels.

  3. MDN: 407 Proxy Authentication Required

    Official documentation · Confirmed on:

    Read on 2 November 2026: 407 means the request lacks valid credentials for the proxy; the response carries Proxy-Authenticate; the client may repeat the request with a new or replaced Proxy-Authorization header.

  4. MDN: Proxy servers and tunneling

    Official documentation · Confirmed on:

    Read on 2 November 2026: the CONNECT method opens a tunnel and is how a client behind an HTTP proxy reaches TLS sites on port 443; not every proxy supports CONNECT or allows other ports.

    It does not mention SOCKS.

  5. Proxy302 product facts and price list

    Product observation · Confirmed on:

    Product facts file of the site (checked against the console, the backend and the price table on 18-19 October 2026): prices in US$ (1 PTC = US$1), lease terms, protocols and ports, no free trial.

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