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Implementing an SSL-Based Network?
A Nominal Coward asks: "I've been doing some research into making my communications more secure, everything from email to news, from IRC to www. Most of the information I've found repeats one suggestion, 'tunnel your connections over SSL.' Yet while everyone claims this is the best thing to do, no one seems to explain how. I haven't been able to find a faq, howto, or demonstration of how to set this up properly; just lots of people saying 'SSL is good.' What am I missing? I've downloaded and installed stunnel, a free (speech & beer) SSL tunneling proxy, but - don't laugh - now what? All I've managed to do is make an SSL connection to an IRC server a friend set up specifically for that purpose. Where do I go from here in order to secure my other connections, like mail, news, and web? Do I have to subscribe with providers who explicitly provide SSL access, if so, which are recommended? I would appreciate advice from others who have managed to get this working."
Yes, as with every other protocol/combination of protocols (HTTP over TCP overIP), both ends of your many communications will need to speak the same way.
For mail, some providers offer pops (that is, secure POP3), but you'll have to ask around to know which ones do. Another way to go is Web mail: those packages usually allow https connections. But don't forget that with both these tools, your mail is only secure between you and your ISP: the SMTP protocol your provider's server use to deliver it to other servers is not encrypted. If you really want one end to the other secure mail (as in: nobody will be able to read it unless they are the intended receiver or they're the NSA or CIA), then use PGP, GPG or any other good mail encryption package. Then it'll reach your recipient in a unreadable format. But all your recipients must have a public key, else you won't be able to encrypt it in the first place (so for helpdesks, mailing-lists, etc. it won't work).
For news, www, etc., do you intend to encrypt what you receive (content)? What you receive (URL)? What you send (even if it ends up on a public nntp server)? For some of those, it won't work because you'd want every connection to be encrypted, period. Normal web servers essentially serving "free" info don't need that, and there's some overhead if you encrypt everything. So it won't be put in practice.
Usually people use stunnel for, eg, remote X sessions, where you don't want other people to spy what you're doing. A couple apps also use ssh to do the same (cvs). But in each case, both ends of the communication must be properly set up to communicate through an encrypted layer.
IPsec (as mentionned in another post) is also good, but as soon as your packets leave the other IPsec end (as in, leave the corporate firewall), your communication will again be very plain to read.
Your question, and the answers, have confused apples and oranges. They look similar (round, fruit), but there are some key differences.
Specifically, you could use a tunnel (stunnel, ssh), or you can use applications that directly support SSL. Setting up the applications takes a bit of research since it hasn't been standardized yet, but it's not too hard once you figure out where the documentation has been hidden. (Sometimes in the source code. *grrr*.) Setting up a tunnel is probably a bit easier, but it requires that the server explicitly provide a tunnel.
The benefits of a tunnel is that it provides a "one size fits all" solution - if you can do it for one application, you can do it for others. More importantly, you can use it with applications that don't yet support SSL directly.
The benefits of direct SSL support is that the clients can almost always verify the identity of the server (it is possible to set up a server so it doesn't require an X.509 certificate, but it's much more common for the server to require one). Optionally, the server can require that clients provide a certificate to identify themselves.
If you control the server, the choice may come down to authentication and identity. If you don't care who connects, or who they connect to, e.g., because you'll be using (username,password) to log in, you should probably go with a tunnel. If you need to establish identity, or want to use a "login-less" mechanism, you should probably go with direct SSL and possibly require client certs.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
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A talk was given at the USENIX conference last week in California in which the throughput performance of SSL/TLS was compared to that of IPsec. IPsec won easily in all cases.
Personally, I prefer IPsec since it can be used to encrypt and authenticate all IP layer traffic. If you're tunneling services over SSL, you're still leaking information to an eavesdropper (i.e. "I know you transferred 200 kB of mail via your tunneled pop3 connection"). With IPsec, it becomes difficult to differentiate between higher level protocols. UDP over IPsec doesn't look any different than TCP.
IPsec is also nice because it's starting to gain widespread industry acceptance. Setting it up on the free Unixes is very easy. Windows 2000 and XP come with it as a standard feature. I don't know if MacOS X 10.1 comes with it, but the forthcoming 10.2 release (Jaguar) includes it.
noah
I've done similar research and here's what I've discovered.
IPSec is usually used for connect LAN's across the internet because it can encrypt all traffic. The one puzzling thing I've found about IPSec is that once its run, it takes over the the IP, that is you can't run regular IP and IPSec at the same time. This part confused me, as it seemed to indicate that I can't run an open HTTP server on port 80 with accessability to the outside world. Now, I'm sure there's a way around this, I just wasn't able to find it before I realized that stunnel would fit my needs.
Stunnel (found here) is able to encrypt (using SSL) and network connection, so lets say you want to use it to secure POP email, you can use the POPS port(which escapes me now) and have STUNNEL sit there and redirect connections to the POP port, then you can turn off outside access to POP through your firewall, and low and behold you have POPS accessable to major e-mail clients without needing the functionality built into the e-mail server. You can do this with anything, and yes the same thing can be accomplished with SSH, but the one thing is that you need to log into SSH first, because it tunnels all traffic through port 22. Now this can be a good thing too, you can close all the ports except for port 22, and require everyone who wants access to your system to log in using a private key. The configuration is a pain because you'll have to configure each users Putty or other client to forward the connections. Its best use, I think is for tunneling windows clients like PCAnywhere throughout your enterprise and passed the firewall. As for News? I've never heard of NNTPS, but I wouldn't be surprised if its the the same. For web, that's simple, just go get yourself a certificate and follow the openssl instructions. You can even sign your own if you don't want to spend on a Verisign one.