Category Archives: SSL

Using Letsencrypt with Wowza Media Server

As part of a work project, I needed to set up Wowza Media Server to do video streaming. As the webapp (which I wrote using the excellent ionic 3 framework) is running under https, it won’t accept video traffic coming from non-encrypted sources. Wowza has some pricey solutions for automatically installing SSL certificates for you, you can also purchase ones however these days I don’t see why everyone doesn’t just use the free and easily automated letsencrypt system. Unfortunately however, letsencrypt doesn’t let you run servers on different ports particularly easily, although it does have some hooks to stop/start services that may already be listening on port 443 (ssl). I happen to be using a redhat/centos distro, although I’m pretty sure the exact same instructions will work on ubuntu and other distros.

Firstly, you need to download the wowza-letsencrypt-converter java program which will convert letsencrypt certificates to the Java format that Wowza can use. Install that prebuild jar under /usr/bin.

Now, create a directory under the Wowza conf directory called ssl and create a file called jksmap.txt (so for example full path is /usr/local/WowzaStreamingEngine/conf/ssl/jksmap.txt) which lists all the domains the Wowza server will be listening on like:

‘secret’ is not actually a placeholder; it’s the password that the wowza-letsencrypt-converter program sets up automatically so keep it as it is.

Configure SSL on the Wowza server by editing the VHost.xml configuration file (find out more about this process in the wowza documentation). Find the 443/SSL section which is commented out by default and change the following sections:

Note the <KeyStorePath>foo</KeyStorePath> line – the value foo is ignored when using jksmap.txt, however if this is empty the server refuses to start or crashes.

Next, install letsencrypt using the instructions on the certbot website.

Once you’ve done all this, run the following command to temporarily stop the server, fetch the certificate, convert it and start the server again:

Then, in order to ensure that the certificate continues to be valid you need to set up a cron entry to run this command daily which will automatically renew the cert when it gets close to its default 3 month expiry time. Simply create /etc/cron.d/wowza-cert-renewal with the following content:

Easily setup a secure FTP server with vsftpd and letsencrypt

I recently had to set up a FTP server for some designers to upload their work (unfortunately they couldn’t use SFTP otherwise it would have been much simpler!). I’ve not had to set up vsftpd for a while, and when I last did it I didn’t much worry about needing to use encryption. So here are some notes on how to set up vsftpd with letsencrypt on ubuntu 14.04 / 16.04 so that only a specific user or two are permitted access.

First, install vsftpd:

Next, you need to make sure you have installed letsencrypt. If not, you can do so using the instructions here – fortunately letsencrypt installation has got a lot easier since my last blog post about letsencrypt almost 2 years ago.

I’m assuming you are running this on the same server as the website, and you’re wanting to set it up as ftp on the same domain or similar subdomain as the website (eg ftp access direct to example.org, or via something like ftp.example.org). If not, you can do a manual install of the certificate but then you will need to redo this every 3 months.

Assuming you’re running the site on apache get the certificate like:

You should now have the necessary certificates in the /etc/letsencrypt/live/example.org/ folder, and your site should be accessible nicely via https.

Now, create a user for FTP using the useradd command. If you want to just create a user that only has access to the server via FTP but not a regular account you can modify the PAM configuration file /etc/pam.d/vsftpd and comment out the following line:

This lets you keep nologin as the shell so the user cannot login normally but can log in via vsftpd’s PAM layer.

Now open up

Because we’re running behind a firewall we want to specify which port range to open up for the connections (as well as port 21 for FTP of course):

If you want to make it even more secure by only allowing users listed in /etc/vsftpd.userlist to be able to log in, add some usernames in that file and then add the following to the /etc/vsftpd.conf configuration file:

You can test using the excellent lftp command:

If the cert is giving errors or is self-signed, you can do the following to connect ignoring them:

Hiding the list of sites on your server

Following on from switching my server to use HTTPS/SSL with the excellent Lets Encrypt free SSL certificate authority, after I enabled SSL on the first domain and you connect via HTTPS to any of the other domains I noticed that the browser comes up with an error like “You tried to get to site xxx.com but the certificate was issued for yyy.com”. I’m not sure about the specifics of the HTTPS protocol and certificates, but I don’t really want people easily being able to get a list of all the virtual hosts that are on my server. If you use the default Lets Encrypt client to just get one certificate for all domains on your server then when the certificate is passed to the client they will be able to see all the domains anyway, however if you issue a certificate for each virtual host as per the script in my other post, at least you can restrict what people see.

To make it even more secure and disallow even one valid certificate from being shown by default, you can create a new default vhost which will display a dummy certificate. To do this, you first need to create a random self-signed certificate:

Just hit enter to all of those questions. Then, create a file in /etc/apache2/sites-enabled called 00default-ssl.conf and place the following commands in it:

Job done!

Easy guide to free SSL with Lets Encrypt

I was excited to hear the other day that the beta of the lets encrypt project had gone live. For those of you that don’t know this is a great project that provides free SSL certificates to any website with the aim of finally moving much of the internet to SSL. However it’s not quite as easy to use as I had hoped, so I documented the process and the issues I ran in to below with the aim of helping some other people out that are wanting to do the same. My setup is apache on linux ubuntu but it should be true for most other flavours of linux.

Firstly, I downloaded and installed letsencrypt on my server as per the instructions:

I had thought that simply running their advised command of:

would convert my apache setup to use https and provide a certificate for each domain on my server. It doesn’t. Whilst it’s a great tool it is still in beta and even after that I’m not sure if the auto configuration functionality would be included. My first issue was that it presented a long list of all the domians in my apache config; some of which were live and some wern’t. You have to select which you want to get a certificate for. However if you select any that are not accessible or not supported (i18n domains ie those beginning xn-- or wildcard domains) then the process dies with an error and you have to restart selecting which domains you want. This is clearly an issue they could fix pretty simply in the code and hopefully that will happen before long. Also, you have to renew the SSL certs every three months and I believe that you have to go through this same process again each time rather than just hitting a renew button.

Another issue that I ran against which is probably more of a design issue is the idea that it issues you one certificate per server. This is fine if you are just hosting one set of domains; however if you have multiple virtual host entries or host multiple sites that are logically separate you probably don’t want to go down this route.

So, because of these issues I gave up on the automatic apache client and wrote a little script that gets a certificate for each virtual server configuration file and excludes i18n domain names, wildcard, localhost and optionally any others. You should be able to just run this script once every few months and it will automatically regenerate all your SSL certificates without having to change any of your config:

Just save that to a file like /etc/apache2/regen_ssl.sh and run it with bash, or paste it directly into your shell and you will then get a load of directories under /etc/letsencrypt/live/ with your certificates in. Each directory should be called after the first ServerName configuration option in the particular virtual host configuration file.

To get the certificates auto-renewing you want to edit the crontab to execute this every few months:

BUT, the process doesn’t end there – you have to set up apache for each domain you want to enable ssl on. First, enable SSL globally:

Also make sure to update your firewall to allow HTTPS (port 443) traffic. Then for each virtual host you should change the header line from:

to

Then you need to enable SSL and specify the certificates:

A service apache2 graceful should then mean you can access your site via https.

If you want to force traffic to use HTTPS there are a number of different routes; the correct way is to use HSTS; however if for some reason you discover that your site doesn’t work correctly using HTTP (eg you have iframes or javascript that is not on SSL-enabled servers) you want to be able to quickly revert to not force clients to use SSL. For the initial deployment then I used the amazing apache2 mod_rewrite to handle this:

If you are running a blog and you just want to force areas where secure information is transferred (eg user login page) to use SSL so people can’t snoop on your password, you could use something like this (for drupal)

If you’re running a site where you have some mobile or legacy clients accessing your API, but you want new web clients forced to use SSL, you could have some config like this: