#### 3.10.1 HTTP parent proxies

The variable `parentProxy` specifies the hostname and port number of an HTTP parent proxy; it should have the form ‘`host:port`’.

If the parent proxy requires authorisation, the username and password should be specified in the variable `parentAuthCredentials` in the form ‘`username:password`’. Only Basic authentication is supported, which is vulnerable to replay attacks.

The main application of the parent proxy support is to cross firewalls. Given a machine, say `trurl`, with unrestricted access to the web, the following evades a firewall by using an encrypted compressed `ssh` link:

         $ ssh -f -C -L 8124:localhost:8123 trurl polipo
         $ polipo parentProxy=localhost:8124