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Kerberos Support In OpenSSH
Dan writes "Marshall Vale writes on behalf of the MIT Kerberos team and several other parties interested in the availability of Kerberos authentication for the SSH protocol. Kerberos is a network authentication protocol. It is designed to provide strong authentication for client/server applications by using secret-key cryptography. Marshall says that Kerberos support within OpenSSH may be incomplete and needs more work. In particular, implementing draft-ietf-secsh-gsskeyex in addition to any other Kerberos mechanisms will better serve the needs of Kerberos community. Secondly, he says that they would like to reduce user confusion associated with all of the different options for Kerberos and SSH. He suggests adoption of the GSSAPI key exchange mechanism in the IETF draft (which uses Kerberos to authenticate both parties to each other), in order to avoid man-in-the-middle attacks."
All UNIX and Linux distros should have cleartext protocols disabled by default.
I still use telnet, ftp and even rsh as well and I don't feel insecure about it. Transport-mode IPSec between hosts really helps a lot here...
The "moronic passwords"-issue comes mainly from pop3 and different web-sessions these days. What the world really needs is opportunistic IPSec.
I will paraphrase a quote from Mr Bruce Schneier:
"No matter what security measures you implement, the end users are still the weakest link in the chain."
I think it speaks for itself. Passwords can be brute forced via secure protocols as well. Passwords can be copied from stick-it notes on people's monitors, or from knowing their maiden name.
While cleartext protocols should be disabled, many places use them... a LOT. And while I know SSH can replace most of their functionality, many places have scripts that have been running for years that would need man power to rewrite (even if changing only one line) which makes it difficult for many organizations decide this is a priority.
Heck, I had a hell of a time convincing our organization to move from SSHv1 to SSHv2 due to the man-in-the-middle attacks.
There are other parties interested in Kerberos?
Idol Star Astronomer
i have a mod for putty that can do gssapi+kerberos auth for users. windows client to the linux/unix openssh servers.
we're beta testing (or will start soon) but it works!
respond if you're interested...
...or maybe not.
Yes. Scenario: 500 *nix servers, team of 10 administrators. Solution 1: Each user gets a login created on each machine, and then they login, create an ssh key, and distribute the public key to all other machines. Later, when that person leaves, all those keys and all those user accounts get deleted. (Given, you could use NIS/LDAP/etc to try and alleviate the user-account side of the issue. But you didn't mention that as part of your RSA solution, and note that each of these solutions has potential inherent security problems.) Solution 2: Setup kerberos. Authenticate all users for all machines securely from one location. Add and delete user accounts from one location.
"No nation could preserve its freedom in the midst of continual warfare."
--James Madison
The main advantage of using Kerberos for key exchange is the elimination of the known_hosts file, and the tendency for ssh users to accept any
old key offered by the server the first time they connect. This common behavior exposes the user to the risk of man-in-the-middle attacks. If I've tricked your stack into connecting to me instead of the host you thought you were getting, I can spoof both ends of the connection and intercept your traffic in the clear. Also, Kerberos authentication is two-way (server to client AND client to server)
"Even if you are on the right track, you'll get run over if you just sit there" - Will Rogers
I am unable to get to the article (slashdotted) but there is an already existing GSSAPI patch for OpenSSH here: patch.