nginx proxy_pass через прокси

GET http://w.backend/ HTTP/1.1

GET / HTTP/1.1
HOST: w.backend

proxy_set_header    Host    $host:$server_port;
#proxy_set_header   Host    $host;

server_name flibusta.dom;

        location / {
                # First attempt to serve request as file, then
                # as directory, then fall back to displaying a 404.
                try_files $uri $uri/ =404;

                proxy_set_header Host flibusta.i2p:80;
    #proxy_set_header X-Real-IP $remote_addr;

    proxy_pass http://127.0.0.1:4444;
}

curl -vv http://flibusta.dom
* Rebuilt URL to: http://flibusta.dom/
* Hostname was NOT found in DNS cache
*   Trying 172.17.0.2...
* Connected to flibusta.dom (172.17.0.2) port 80 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.39.0
> Host: flibusta.dom
> Accept: */*
>
< HTTP/1.1 403 Bad Protocol
< Server: nginx/1.6.2 (Ubuntu)
< Date: Mon, 23 Nov 2015 19:51:42 GMT
< Content-Type: text/html; charset=UTF-8
< Transfer-Encoding: chunked
< Connection: keep-alive
< Cache-control: no-cache
< Proxy-Connection: close
<

GET / HTTP/1.0
Host: flibusta.i2p:80
Connection: close
User-Agent: curl/7.39.0
Accept: */*

2016/02/03 09:29:06 [error] 22075#0: *12 readv() failed (104: Connection reset by peer) while reading upstream, client: 9x.xxx.xxx.xx4, server: *.i2p.domain.tld, request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:4444/", host: "flibusta.i2p.domain.tld"