To configure HTTP or Socks proxy in Opera on Windows, follow these steps.
Opens the Settings window directly by the operating system Windows.
Specify the proxy settings depending on its type. If possible, we recommend using Socks 5 proxy. At the moment this is the most anonymous protocol.
If you are using an HTTP proxy authorization, the window with the login and password will be immediately as soon as you try to access any website on the Internet.
Browsers does not support Socks proxy authorization. In such cases it is necessary to use the special program. For example, Proxifier.
More about configuring Proxifier on Windows.
We want to draw attention to the fact that the proxy settings is produced directly in the Windows operating system.
If you use a VPN, it may be undesirable situation when traffic first goes to the proxy server, and then only on VPN (chain: Proxy + VPN). While the best option in terms of security and anonymity is considered chain: VPN + Proxy.
To solve this problem, the best option is using special program Proxifier.
Or need to use a browser that supports proxy settings directly in the browser. More about proxy settings in Firefox on Windows.