I have previously talked about speeding up your site by using Squid as a reverse proxy to cache served pages. This is a great thing to do, but presents a problem now that all sites are moving over to HTTPS, since for various technical reasons reverse proxies can’t really handle HTTPS.

These days the standard way of doing this seems to be using Varnish as a cache, and Squid seems to be a little “old hat”, however I have several client estates which were set up before Varnish came on the scene, so I needed a solution I could get up and running very quickly.

Terminating HTTPS

Thankfully, the solution is very similar whatever reverse proxy you’re using. The solution is simple, you need to install something that terminates and handles the HTTPS session before sending it to your proxy. The simplest way to do this is to install NGINX and configure it to handle HTTPS sessions.

1) Disable Apache’s handling of HTTPS (if you’ve got an existing, un-cached, HTTPS server).

2) Install the basic nginx apt-get install nginx-light

3) Configure nginx to forward to your proxy (which you have previously configured to listen on port 80)

After restarting nginx, you should be able to see https requests coming in on your squid proxy logs.

Gotchas

The biggest gotcha that you’re going to hit is that if you’re checking whether a request is HTTPS in your app (e.g. for automatically forwarding from insecure to secure), you’re not going to be able to use the standard protocol checks. The reason being is that HTTPS is being terminated by nginx, so by the time the session hits your app, it will not be seen as secure!

To perform such a test, you’re instead going to have to check for the X-Forwarded-Proto header instead ($_SERVER['HTTP_X_FORWARDED_PROTO'] in PHP).

On the Indiewebcamp wiki, there’s a page discussing HTTPS, the support for which is strongly recommended. As I’ve mentioned previously, at this stage all non-encrypted communication forms (including traditional port 80 HTTP) should be considered deprecated and dangerous.

Indieweb compatible sites are encouraged to get a higher level as possible, and thanks to some prodding, I’ve finally moved both this blog and my feed over to HTTPS only, with HSTS and forward secrecy.

This got me thinking, perhaps it would be worth adding a “Level 7” (or perhaps Level 6.5) to this, and to suggest that Indieweb sites should also be made available as .onion hidden services on Tor?

Pros

  • Anonymity. Would go a large way towards protecting communication metadata (who know’s whom), which is a goal we should move towards in a world of endemic selector based surveillance.
  • Encryption. Traffic within the tor network is end to end encrypted, and there is some discussion of whether this renders HTTPS unnecessary.

Cons

  • Tor has nothing to do with HTTPS, although it is encrypted. However, the HTTPS levels page seemed a good place to put the suggestion.
  • Could be seen as endorsing one service. Tor is Free software and is pretty much the only game in town when it comes to anonymity networks, but does that constitute a silo? Probably not, but is a point for discussion.
  • No certificates for .onion. There are currently no certificate providers available for .onion domains. But, this may not be a problem.

Anyway, just mooting this as a point for discussion.

We all know how important it is to secure web servers with encryption. As I’ve mentioned before, port 80 HTTP should be considered deprecated at this point!

Just as important (potentially more so), but often overlooked, is to ensure that your email server is also secure.

STARTTLS is a technology that lets you start an encrypted session during a standard SMTP connection. In the same way as HTTPS secures web, STARTTLS will secure email in transit from your mail client to the server, and from server to server. This makes it much harder to passively read the traffic, and having more encrypted traffic on the internet is only ever a good thing.

This only protects email in transit from server to server of course, so this is not a replacement for end to end encryption methods like PGP, but it does complement it… and since most email is still sent insecurely, this adds extra security without requiring your users do any extra work.

It’s easy to set up (for Exim at least), and it transparently runs on port 25, so there’s no reason not to!

Generate your keys

As with web, you’ll need a server key and certificate file.

For my public mail and MX relay servers, I decided to use valid certificate authority certificates. Clients, and some relaying servers, will throw a certificate error for self signed certificates, but others will not. Better safe than sorry, and since I already had a valid certificate on my site for the server in question, I simply recycled the certificate.

If this is your internal server, you can use a certificate signed by your own certificate authority, supported by the machines in your organisation.

The default exim configuration expects to find certificates in /etc/exim4/exim.key and /etc/exim4/exim.crt.

Enable TLS

The basic STARTTLS configuration by simply editing exim4.conf.template and setting MAIN_TLS_ENABLE = yes in the tlsoptions section. Restart exim and you should have STARTTLS support enabled.

As with a web server, you can configure ciphers etc at this stage. On my server at least, the defaults seemed reasonably strong, but as we learn which ciphers have been compromised by GCHQ and the NSA, we might need to tweak these.

Test your configuration

Next, you should test your configuration.

To do this, the simplest way is to use a program called swaks, which you should find in your distro’s package library.

Should produce a result something like…

If you get an error when starting TLS examine your exim log for the cause.