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State of Secure Wireless Networking?
Mr. Sketch asks: "At my office, they want me to add a wireless network and it seems like it could be possible to do it in a secure way, but I'm not 100% confident. The setup I was thinking of was 802.11g only (no backward 802.11b compatibility), WPA-PSK with AES encryption with a 15 character password consisting of upper and lower case letters and numbers and special characters, MAC filtering, no ssid broadcast, and no default anything (ssid, passwords, etc). How secure would this network be? What type of attacks would it be vulnerable to? I haven't found any tools to crack AES, only WEP, does that mean it's secure or I just that I haven't looked hard enough? I want the wireless computers to still be able to access the computers on our network, in fact ideally, I just want it to be a wireless extension of our wired network, but only if it's secure enough. I'm sure there are plenty of other companies who want to add wireless to their network, but want to be reasonably confident that it will be secure and are unsure of the current state of wireless security."
and address. I will tell you if its secure ;)
and the week before that, and the month before that. Do not rely on your wireless access point's built-in encryption and authentication under any circumstances. Use it as a barebones minimum and then drop a VPN on top of that. Make sure the access points terminate on an insecure network isolated from the rest of your trusted LAN and require VPN access to reach the trusted side. Anybody that was trusting LEAP just got burned last week so don't make the same mistakes about trusting a hardware implementation when there's proven software VPN solutions that have stood the test of time.
How secure would this network be? What type of attacks would it be vulnerable to? I haven't found any tools to crack AES, only WEP, does that mean it's secure or I just that I haven't looked hard enough?
AES itself is considered a strong encryption technology. How secure it will be for a WiFi connection is anyone's bet. It is the approved NIST standard. (US centric) see http://csrc.nist.gov/CryptoToolkit/aes for more information.
You could enhance it by putting in an SSH VPN to a seprate box on your network.
Connect your AP to the network through a firewall that only allows the SSH tunnel to communicate with the tunnel server, and drops all other traffic. The ap would provide it's own DHCP server to eliminate unnecessary load on the firewall.
Then again, I work in an environment where we do not allow any wireless networking.
-Rusty
You never know...
If I understand wireless networking correctly, somebody can key in the info you give them for access to the network, and then allow unsecured, "ad hoc" network access -- meaning people could get into your network through their computer. Do you have control over all of the computers? I would worry about such a security hole if it's possible.
I do some wardriving and I can tell you that I wouldn't even attempt to break into what you just described wirelessly. If I did want in, it would be much easier to walk in the front door and socially engineer the secretary. WEP has been broken, I seem to thing one form of WAP has been, not sure which, but it is so difficult that a physical attack would be much more likely. Is your wired network that secure or can anyone plug into an open port and have full access?
You should map the network, understand where the signal reaches and try to tune the power to only go where you want it.
If you are paranoid enough to want to try all of the layers of encryption, and you should be, its fun to do. Then go with the setup you have and put IPSEC on top, that will make it at least as secure as your wired side. Be aware that you won't get anywhere near 54MBs with all of the encryption loading down the system, so it will be slow.
I am not aware of any attacks that could brute force this setup, but it would be easier for someone to socially engineer it, MAC addresses can be cloned, VPN logins stolen, so some form of automated monitoring would be nice, checking for duplicate logins, unauthorized times. Why is Bob trying to authenticate at 3AM? That kind of stuff.
This gives you bomb-proof security using proven technology, avoids key distribution problems and allows you to upgrade the wireless infrastructure with less effort.
http://www.nortelnetworks.com/products/01/contivit y/
If there is any weakness in this setup, it's probably in WPA-PSK. It's intended more for home use than for corporate WLANs. If the PSK password gets compromised, you could be in for trouble. Of course if the password is strong, the only attack I know of is to get physical access to one of the wireless nodes. I'm not all that familiar with the new protocals; the attacker may still have to find a way past AES to make use of the compromised PSK.
All this security stuff to keep people out of your network, but don't forget about people jamming up your network. It only takes one client to mess up everything.
I'm running a small WISP and have found that some radios can crash my access points. Make sure you get a real good AP, like Cisco or something. I've use the cheap ones. Linksys, D-Link, and I end up having problems. So I built my own with a Soekris board using Linux. Same problems. Switch to FreeBSD (m0n0wall). Same problems. The dam things crash almost every day. The biggest reason... Power Save Mode on a client computer.
The above is not worth reading.
One of the most difficult problems is that since linksys boxes are so cheap these days, it's not unusual for a misguided employee to just bring his old one from home and plug it into the corporate network. Hey the super-secure ultra-locked down DMZ'd VPN one you provided didn't even show up in the pop-up menu so obviously it was his right to just get something working.
Some really high-end wifi equipment will scan the airwaves for unauthorized signals, plus scan the wired network for IP addresses that are act like access points and then notify you or even attempt to shut them down.
everything looks fine except for the WPA-PSK part. Use WPA with 802.1x authentication instead of pre-shared keys. Its more secure and makes overall management easier (want to lock a user out, just disable his account on the server; users can use the same password as they use on their VPNs or on your regular network, a new master-key is generated per session, you can allow users to login only at specific times or from specific access points). The only problem is that authentication takes a wee bit longer than PSK each time, but unless you have users using voice-over-IP and walking around from access-point to access-point you wont notice any difference with 802.1x
It's only as secure as any new encryption method that comes out. WEP was thought to be secure until it was proven not to be. Now, WPA is said to be secure. It may or may not be. You won't know until you're either hacked or someone else is.
:)
Be warned: Turning off SSID broadcasting, enabling MAC filters, or even lowering your AP power levels can result in unexpected behavior.
For instance, my Dlink access point/router has a firmware update that features WPA, but it doesn't work with my Gigabyte w/l card. A few small packets can get through, but large packets are right out of the question. Sometimes there will be windows of a few seconds where I can get traffic through, but they go away in 5 seconds or less.
I switched back to WEP and everything was peachy. I then turned off SSID broadcasting. My w/l cards (all of them) would no longer recognize my active network because they couldn't "see" it. There isn't a way to hard-code or static-set the SSID name, channel, etc into my cards. You'll need to find one with hardware or software that supports connecting to networks that don't have a visible SSID. Basically, one that remembers what channel it was last on.
It's frustrating. Also, if you're paranoid about security, run your traffic through a VPN. It's a pain in the butt to set up, but it should work. Get ready for lots of support calls, too. Calls like "It was working, but I rebooted my machine and now it can't see the network", "the network is slow", "Why does it say the signal quality is low a lot of the time and I'm using the network just fine?"
You'll hear lots of that
I would recommend that you implement (now) WPA with TKIP encryption. If you're a MS shop, and have an Active Directory infrastructure, adding MS IAS (internet authentication server) to that is very easy, and you're probably already licensed. Then you get to choose between authentication methods, and MS supports (and integrates into XP) EAP-MS-CHAP and EAP-TLS, basically login/passwd and digital certs, respectively. I would avoid Preshared Secret Keys (PSKs) due to their vulnerability to off-line dictionary attacks, unless you're willing to generate the PSKs in a cryptographically sound manner and push the length out quite a bit.
Likewise, I would counsel caution about using the AES encryption. If you purchase all of your gear from one vendor, you'll probably be OK, but there are a couple of gotcha's that you need to know about. First, the IEEE 802.11i standard which specifies CCMP (the AES crypto) is not yet final. It's extremely unlikely, but it _could_ change (we meet next week). Any vendor you choose today would likely provide updates in the event of a change, but who knows. More importantly, because the 11i is not final, the Wi-Fi Alliance has not yet integrated CCMP into their testing. So not only do you have absolutely no guarantee of interoperability, no one other than the vendor has tested the crypto implementation. Most crypto folks have a good feeling about AES, but no sane cryptographer trusts an implementation that hasn't been 3d party tested.
Unfortunately, if you need to support Linux, you're in for a hard time. I am not aware of a complete working set of client-side "stuff" to integrate into this lashup, although I did notice the beginnings of some support in the recent 2.6.5 kernel. Do NOT assume that you will be able to get linux working in this environment right now. It's comming..... but it's ain't there yet.
Now, on the subject of some of the other "advice" offered here....
There is a book out from Microsoft Press that gives a lot of background, and takes you step-by-step through getting all of this crap up and running in their environment. I have met the author, and know a number of the contributors from the committee. I highly recommend it, available here. I sincerely hope all of this helps....