Some ikiwiki plugins make outgoing HTTP requests from the web server:

* [[plugins/aggregate]] (to download Atom and RSS feeds)
* [[plugins/blogspam]] (to check whether a comment or edit is spam)
* [[plugins/openid]] (to authenticate users)
* [[plugins/pinger]] (to ping other ikiwiki installations)

If your ikiwiki installation cannot contact the Internet without going
through a proxy, you can configure this in the [[setup file|setup]] by
setting environment variables:

    ENV:
        http_proxy: "http://proxy.example.com:8080"
        https_proxy: "http://proxy.example.com:8080"
        # optional
        no_proxy: ".example.com,www.example.org"

Note that some plugins will use the configured proxy for all destinations,
even if they are listed in `no_proxy`.

To avoid server-side request forgery attacks, ensure that your proxy does
not allow requests to addresses that are considered to be internal.