David Westerfield

Theology, Culture, Technology, Reviews, and Other Commentary



OpenVPN Sharing a TCP Port with SSL on NGINX and Apache? Yeah It’s Possible

The reason I say “it’s possible” is because for the longest time I didn’t think it was because I couldn’t get anything to explain how it works. I’m absolutely baffled there isn’t more information out there about this. It seems like web managers and techs would be all over this, but there’s barely any information out there on this. I had a hard time finding documentation on OpenVPN’s site itself!

As one guy stated here (the post where I finally understood how this works) it’s not really “sharing” the port per se, but OpenVPN is deciphering between HTTP/S traffic and OpenVPN traffic and then forwarding web traffic over to another port, defined below. That’s crucial to understand.

Before I start, I want to note this doesn’t have to be done on an SSL port, as I understand it. I’m just using that as an example because it seems to be the most logical way to make it work if this is your configuration (you know, an SSL VPN going to an SSL port).

It should also be noted in this configuration example that OpenVPN, using the port-share parameter, is actually doing the listening on TCP port 443 and acting as a proxy itself that forwards non-OpenVPN traffic to the NGINX SSL port which we’ll layout below. You cannot do this utilizing UDP, that I know of.

So here’s what you do.

1) Set your NGINX or Apache listening ports. Set your NGINX standard http port 80 and SSL listening port to something OTHER than 443 … so, for arguments’ sake, let’s set it to 4443.

So it would look like this for Apache and NGINX:

For Apache, in the main httpd.conf (Windows) or in ports.conf (Ubuntu/Linux):

Listen 4443

For NGINX, in /etc/nginx/sites-available/defaults:

server {
listen 4443;

location / {
root /web/etc/blah;
}
}

Once implemented, restart your respective service, Apache or NGINX.

2) Next, you’re going to set your OpenVPN server parameters. Set your listening port to 443 from its standard 1194 and add the port-share parameter to point to the Apache or NGINX port created above. The config should look as follows now:

port 443
port-share 127.0.0.1 4443
proto tcp

OpenVPN will now be ready to accept connections over 443 and route the appropriate https/SSL traffic to Apache or NGINX.

3) Change your firewall settings. Leave your TCP port 80 rule pointing directly to Apache or NGINX. Then point your SSL rule to TCP port 443 running on your OpenVPN server. OpenVPN will now catch the traffic directed at it and decipher between OpenVPN traffic and HTTPS traffic.

4) Change the configuration in your OpenVPN clients. Point your OpenVPN clients to TCP port 443 instead of the port you were using before:

remote domain.name.com 443

or

remote [IP ADDRESS] 443

Hope it works. Cheers!

13 Comments

  1. Hi,

    First, thanks for sharing, it could have help me a lot if I havn’t misunderstood : « For NGINX, in /etc/nginx/sites-available/defaults: »

    So to future travalers, beware, you should edit you’re website configuration and absolutely not /etc/nginx/conf.d/default ;)

    After a long time of search I finally found the problem and solve it : now it works fine. So, thanks ! :-)

  2. hi
    what should i do for this (Leave your TCP port 80 rule pointing directly to Apache or NGINX. Then point your SSL rule to TCP port 443 running on your OpenVPN server)
    Can you explain more?
    tnx

  3. I’ll try to break it down:

    1) Set your OpenVPN listening port to 443 … all requests to TCP 443 for either web/https or OpenVPN will come through this port: “port 443″

    2) Set your port-sharing rule … this is what your Apache/NGINX servers’ port is set to, on the same box, in other words, this is what you’re telling OpenVPN to connect to for web/https traffic; for argument sake assume your Apache server is listening on port 4443): “port-share 127.0.0.1 4443″

    Make anymore sense?

    • i have cent os 5 32 bit
      and apache
      in the httpd.conf
      I’ve changed Listen 80 to Listen 4443
      and Open VPN settings to the following

      local [IP ADDRESS]
      port 443
      port-share 127.0.0.1 4443
      proto tcp
      dev tun
      tun-mtu 1500
      tun-mtu-extra 32
      mssfix 1450
      ca /etc/openvpn/easy-rsa/2.0/keys/ca.crt
      cert /etc/openvpn/easy-rsa/2.0/keys/server.crt
      key /etc/openvpn/easy-rsa/2.0/keys/server.key
      dh /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem
      plugin /etc/openvpn/plugins/rp.so /etc/openvpn/plugins/rp.cnf
      client-cert-not-required
      username-as-common-name
      server 10.8.0.0 255.255.255.0
      push “redirect-gateway def1″
      push “dhcp-option DNS 8.8.8.8″
      push “dhcp-option DNS 8.8.4.4″

      and OpenVPN Config File (.ovpn) Is as follows

      client
      dev tun
      proto tcp
      port-share 127.0.0.1 4443
      remote [IP ADDRESS] 443 # – Your server IP and OpenVPN Port
      resolv-retry infinite
      nobind
      tun-mtu 1500
      tun-mtu-extra 32
      mssfix 1450
      persist-key
      persist-tun
      ca ENGLAND.1.crt
      comp-lzo
      verb 3
      auth-user-pass
      script-security 3

      What I’m doing wrong?
      And make adjustments where
      I did not do?
      Completely explain it?
      Thank you

  4. There’s SSLH which allows for HTTP, SSL, SSH, OpenVPN, tinc, XMPP on the same port. http://www.rutschle.net/tech/sslh.shtml

  5. port-share is OpenVPNs ass, port is it’s mouth. It’s shits useless data out and other deamons are eating it up :+)

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