Tunnelling connections - The Polipo Manual
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### 3.12 Tunnelling connections

Polipo is an HTTP proxy; it proxies HTTP traffic, and clients using other protocols should establish a direct connection to the server or use an ad hoc proxy.

Due to wide-spread brain-damage1, however, there are some circumstances in which establishing a direct connection to the server is not possible. In such situations, it is possible to have Polipo behave as a tunnelling proxy — a proxy that merely forwards traffic between the client and the server without understanding it. Polipo enters tunnel mode when the server requests it by using the HTTP ``CONNECT`' method.

Most web browsers will use this technique for HTTP over SSL (sometimes known as `https') if configured to use Polipo as their `https proxy'. Recent versions of ssh can also use it to cross mis-configured firewalls.

The variable `tunnelAllowedPorts` specifies the set of ports that Polipo will accept to tunnel traffic to. It defaults to ``22, 80, 443`', meaning that Polipo will only tunnel ssh, HTTP and https traffic.

#### Footnotes

[1] Sometimes known as NAT.