+ +
+

nghttpx - HOW-TO

+

nghttpx is a proxy translating protocols between HTTP/2 and other +protocols (e.g., HTTP/1, SPDY). It operates in several modes and each +mode may require additional programs to work with. This article +describes each operation mode and explains the intended use-cases. It +also covers some useful options later.

+
+

Default mode

+

If nghttpx is invoked without any -s, -p and --client, it +operates in default mode. In this mode, nghttpx frontend listens for +HTTP/2 requests and translates them to HTTP/1 requests. Thus it works +as reverse proxy (gateway) for HTTP/2 clients to HTTP/1 web server. +HTTP/1 requests are also supported in frontend as a fallback. If +nghttpx is linked with spdylay library and frontend connection is +SSL/TLS, the frontend also supports SPDY protocol.

+

By default, this mode’s frontend connection is encrypted using +SSL/TLS. So server’s private key and certificate must be supplied to +the command line (or through configuration file). In this case, the +fontend protocol selection will is done via ALPN or NPN.

+

With --frontend-no-tls option, user can turn off SSL/TLS in +frontend connection. In this case, SPDY protocol is not available +even if spdylay library is liked to nghttpx. HTTP/2 and HTTP/1 are +available on the frontend and a HTTP/1 connection can be upgraded to +HTTP/2 using HTTP Upgrade. Starting HTTP/2 connection by sending +HTTP/2 connection preface is also supported.

+

The backend is supposed to be HTTP/1 Web server. For example, to make +nghttpx listen to encrypted HTTP/2 requests at port 8443, and a +backend HTTP/1 web server is configured to listen to HTTP/1 request at +port 8080 in the same host, run nghttpx command-line like this:

+
$ nghttpx -f0.0.0.0,8443 -b127.0.0.1,8080 /path/to/server.key /path/to/server.crt
+
+
+

Then HTTP/2 enabled client can access to the nghttpx in HTTP/2. For +example, you can send GET request to the server using nghttp:

+
$ nghttp -nv https://localhost:8443/
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+
+
+
+

HTTP/2 proxy mode

+

If nghttpx is invoked with -s option, it operates in HTTP/2 proxy +mode. The supported protocols in frontend and backend connections are +the same in default mode. The difference is that this mode acts like +forward proxy and assumes the backend is HTTP/1 proxy server (e.g., +squid). So HTTP/1 request must include absolute URI in request line.

+

By default, frontend connection is encrypted, this mode is also called +secure proxy. If nghttpx is linked with spdylay, it supports SPDY +protocols and it works as so called SPDY proxy.

+

With --frontend-no-tls option, SSL/TLS is turned off in frontend +connection, so the connection gets insecure.

+

The backend must be HTTP/1 proxy server. nghttpx only supports 1 +backend server address. It translates incoming requests to HTTP/1 +request to backend server. The backend server performs real proxy +work for each request, for example, dispatching requests to the origin +server and caching contents.

+

For example, to make nghttpx listen to encrypted HTTP/2 requests at +port 8443, and a backend HTTP/1 proxy server is configured to listen +to HTTP/1 request at port 3128 in the same host, run nghttpx +command-line like this:

+
$ nghttpx -s -f0.0.0.0,8443 -b127.0.0.1,3128 /path/to/server.key /path/to/server.crt
+
+
+

At the time of this writing, there is no known HTTP/2 client which +supports HTTP/2 proxy in this fashion. You can use Google Chrome to +use this as secure (SPDY) proxy to test it out, though it does not use +HTTP/2 at all.

+

The one way to configure Google Chrome to use secure proxy is create +proxy.pac script like this:

+
function FindProxyForURL(url, host) {
+    return "HTTPS SERVERADDR:PORT";
+}
+
+
+

SERVERADDR and PORT is the hostname/address and port of the +machine nghttpx is running. Please note that Google Chrome requires +valid certificate for secure proxy.

+

Then run Google Chrome with the following arguments:

+
$ google-chrome --proxy-pac-url=file:///path/to/proxy.pac --use-npn
+
+
+
+
+

Client mode

+

If nghttpx is invoked with --client option, it operates in client +mode. In this mode, nghttpx listens for plain, unencrypted HTTP/2 and +HTTP/1 requests and translates them to encrypted HTTP/2 requests to +the backend. User cannot enable SSL/TLS in frontend connection.

+

HTTP/1 frontend connection can be upgraded to HTTP/2 using HTTP +Upgrade. To disable SSL/TLS in backend connection, use +--backend-no-tls option.

+

The backend connection is created one per worker (thread).

+

The backend server is supporsed to be a HTTP/2 web server (e.g., +nghttpd). The one use-case of this mode is utilize existing HTTP/1 +clients to test HTTP/2 deployment. Suppose that HTTP/2 web server +listens to port 80 without encryption. Then run nghttpx as client +mode to access to that web server:

+
$ nghttpx --client -f127.0.0.1,8080 -b127.0.0.1,80 --backend-no-tls
+
+
+
+

Note

+

You may need -k option if HTTP/2 server enables SSL/TLS and +its certificate is self-signed. But please note that it is +insecure.

+
+

Then you can use curl to access HTTP/2 server via nghttpx:

+
$ curl http://localhost:8080/
+
+
+
+
+

Client proxy mode

+

If nghttpx is invoked with -p option, it operates in client proxy +mode. This mode behaves like client mode, but it works like +forward proxy. So HTTP/1 request must include absolute URI in request +line.

+

HTTP/1 frontend connection can be upgraded to HTTP/2 using HTTP +Upgrade. To disable SSL/TLS in backend connection, use +--backend-no-tls option.

+

The backend connection is created one per worker (thread).

+

The backend server must be a HTTP/2 proxy. You can use nghttpx in +HTTP/2 proxy mode as backend server. The one use-case of this mode +is utilize existing HTTP/1 clients to test HTTP/2 connections between +2 proxies. The another use-case is use this mode to aggregate local +HTTP/1 connections to one HTTP/2 backend encrypted connection. This +makes HTTP/1 clients which does not support secure proxy can use +secure HTTP/2 proxy via nghttpx client mode.

+

Suppose that HTTP/2 proxy listens to port 8443, just like we saw in +HTTP/2 proxy mode. To run nghttpx in client proxy mode to access +that server, invoke nghttpx like this:

+
$ nghttpx -p -f127.0.0.1,8080 -b127.0.0.1,8443
+
+
+
+

Note

+

You may need -k option if HTTP/2 server’ss certificate is +self-signed. But please note that it is insecure.

+
+

Then you can use curl to issue HTTP request via HTTP/2 proxy:

+
$ curl --http-proxy=http://localhost:8080 http://www.google.com/
+
+
+

You can configure web browser to use localhost:8080 as forward +proxy.

+
+
+

HTTP/2 bridge mode

+

If nghttpx is invoked with --http2-bridge option, it operates in +HTTP/2 bridge mode. The supported protocols in frontend and backend +connections are the same in default mode.

+

With --frontend-no-tls option, SSL/TLS is turned off in frontend +connection, so the connection gets insecure.

+

The backend server is supporsed to be a HTTP/2 web server or HTTP/2 +proxy. Since HTTP/2 requests opaque between proxied and non-proxied +request, the backend server may be proxy or just web server depending +on the context of incoming requests.

+

The use-case of this mode is aggregate the incoming connections to one +HTTP/2 connection. One backend HTTP/2 connection is created per +worker (thread).

+
+
+

Disable SSL/TLS

+

In default mode, HTTP/2 proxy mode and HTTP/2 bridge mode, +frontend connections are encrypted with SSL/TLS by default. To turn +off SSL/TLS, use --frontend-no-tls option. If this option is +used, the private key and certificate are not required to run nghttpx.

+

In client mode, client proxy mode and HTTP/2 bridge mode, +backend connections are encrypted with SSL/TLS by default. To turn +off SSL/TLS, use --backend-no-tls option.

+
+
+

Specifying additional CA certificate

+

By default, nghttpx tries to read CA certificate from system. But +depending on the system you use, this may fail or is not supported. +To specify CA certificate manually, use --cacert option. The +specified file must be PEM format and can contain multiple +certificates.

+

By default, nghttpx validates server’s certificate. If you want to +turn off this validation, knowing this is really insecure and what you +are doing, you can use -k option to disable certificate +validation.

+
+
+

Read/write rate limit

+

nghttpx supports transfer rate limiting on frontend connections. You +can do rate limit per connection or per worker (thread) for reading +and writeing individually.

+

To rate limit per connection for reading, use --read-rate and +--read-burst options. For writing, use --write-rate and +--write-burst options.

+

To rate limit per worker (thread), use --worker-read-rate and +--worker-read-burst options. For writing, use +--worker-write-rate and --worker-write-burst.

+

If both per connection and per worker rate limit configurations are +specified, the lower rate is used.

+

Please note that rate limit is performed on top of TCP and nothing to +do with HTTP/2 flow control.

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