Thank you in advance for any assistance you can provide...
I am trying to talk to a UHF radio (from a PC) over a secure channel, but having some difficulties. Please let me provide just a little background so you know why I’m doing what I’m doing. In the existing system, Internet Explorer (IE) is the client that talks to this radio. When the radio boots up, it sends a webpage over Ethernet to IE and (after the user login), a secure link is established, and the radio can be controlled from IE – the various webpages change as the user maneuvers through the various dropdowns, etc. We’ve been asked to automate this interface now for a production environment. The client is going to be replaced with a PC connected to a great deal of test equipment, and the server will now send XML instead of html to the client. The client is being developed in LabVIEW (from National Instruments) – this has made this task even more challenging.
As all of this secure stuff is new to me, I spent many hours just trying to understand the problem(s) and the lingo. As LabVIEW has some limitations in this area, I found that Stunnel was my best option. Using TCP/IP and sending http to the radio (shown below), I’ve been able (in a non-secure mode, without Stunnel) to communicate and get the opening screen (html) to be returned to me (the XML server output is currently being developed) and displayed in a LabVIEW window.
GET / HTTP/1.1 Host: 10.4.32.1 Connection: Keep-Alive Authorization: Basic YWRtaW46UgEkJHdvtmQx Credentials: admin:Password
I downloaded the binary version of Stunnel.exe (version 4.27 with OpenSSL 0.9.8k dated Mar 2009), then modified the LabVIEW code to call (using a command line approach) Stunnel. In this way, I can’t provide any (dash) options, so it’s completely dependent on the stunnel.conf file. After a number of attempts, I was able to get the client to bind to the server (I think), but I see nothing being returned to me (no html). I must use TLSv1, and ciphers = DES-CBC3-SHA.
I’ve seen examples on stunnel.org that show a great deal more handshaking information than I’m seeing, so I’m wondering if I’m missing some detail in my conf file. For example, my log file ends like this
2009.10.16 13:18:49 LOG7[4812:4776]: FD 208 in non-blocking mode 2009.10.16 13:18:49 LOG7[4812:4776]: SO_REUSEADDR option set on accept socket 2009.10.16 13:18:49 LOG7[4812:4776]: https bound to 10.4.1.8:443
But the example I mentioned goes on after the “https bound” and adds things like …
2009.08.04 12:15:55 LOG7[16648:22996]: proxy accepted FD=320 from 127.0.0.1:48086 2009.08.04 12:15:55 LOG7[16648:22996]: Creating a new thread 2009.08.04 12:15:55 LOG7[16648:22996]: New thread created 2009.08.04 12:15:55 LOG7[16648:8540]: proxy started 2009.08.04 12:15:55 LOG7[16648:8540]: FD 320 in non-blocking mode 2009.08.04 12:15:55 LOG7[16648:8540]: TCP_NODELAY option set on local socket 2009.08.04 12:15:55 LOG5[16648:8540]: proxy accepted connection from 127.0.0.1:48086 2009.08.04 12:15:55 LOG7[16648:8540]: FD 340 in non-blocking mode 2009.08.04 12:15:55 LOG7[16648:8540]: proxy connecting 89.149.253.125:8080 2009.08.04 12:15:55 LOG7[16648:8540]: connect_wait: waiting 10 seconds 2009.08.04 12:15:56 LOG7[16648:8540]: connect_wait: connected 2009.08.04 12:15:56 LOG5[16648:8540]: proxy connected remote server from 192.168.2.3:48088 2009.08.04 12:15:56 LOG7[16648:8540]: Remote FD=340 initialized 2009.08.04 12:15:56 LOG7[16648:8540]: TCP_NODELAY option set on remote socket 2009.08.04 12:15:56 LOG7[16648:8540]: SSL state (connect): before/connect initialization 2009.08.04 12:15:56 LOG7[16648:8540]: SSL state (connect): SSLv3 write client hello A 2009.08.04 12:15:56 LOG7[16648:8540]: SSL state (connect): SSLv3 read server hello A . . . 2009.08.04 12:15:57 LOG6[16648:8540]: SSL connected: new session negotiated 2009.08.04 12:15:57 LOG6[16648:8540]: Negotiated ciphers: AES256-SHA SSLv3 Kx=RSA Au=RSA Enc=AES(256) Mac=SHA1
That make’s me think that I’m not quite there yet. I’ve attached my stunnel.conf, my log file, and the http request I’m making (above). I’m hoping you can find some flaws in my conf file that will get me closer. Other than receiving html, I’m not sure how to know that I truly have a secure connection. I’m thinking I should see a little more in my log file, but I’m not sure.
The other thing I’m not sure about (as I’ve heard differing thoughts) is whether I have to Encrypt my http commands, or does stunnel take care of that somehow? If I have to encypt, how would I go about doing this? Also, (and I’m getting ahead of myself) do I have to open and close a session every time I want to talk, or do I somehow leave the channel open? I’ve read about Session Resumption, but I’m not sure if that is something I need to setup in the conf file, or if that can even be controlled by Stunnel.
Al Gonzalez Principal Software Engineer Compass Call Programs Offensive Information Warfare Raytheon Company
260.429.4354 260.429.5829 fax [email protected]