Hi Prentice,
Could you kindly elaborate on this statement? Is host-based security
safe inside a compute cluster compared to user-based SSH keys?
Thanks,
Ole
On 09-06-2020 21:26, Prentice Bisbal wrote:
Host-based security is not considered as safe as user-based security, so
should only be used in special cases.
On 6/9/20 11:45 AM, Michael Jennings wrote:
On Tuesday, 09 June 2020, at 12:43:34 (+0200),
Ole Holm Nielsen wrote:
in which case you need to set up SSH authorized_keys files for such
users.
I'll admit that I didn't know about this until I came to LANL, but
there's actually a much better alternative than having to create user
key pairs and manage users' ~/.ssh/authorized_keys files: Host-based
Authentication.
Setting "HostbasedAuthentication yes" and configuring it properly on
all the cluster hosts allows a cryptographically-secured equivalent of
what used to be known as RHosts-style Authentication using ~/.rhosts
and /etc/hosts.equiv. Essentially, it allows host-key-authenticated
systems to recognize each other, and once that completes successfully,
the target host trusts the source host to accurately introduce the
user who's logging in.
Once you have host-based authentication working, users can SSH around
inside your cluster seamlessly (subject to additional restrictions, of
course, like access.conf or pam_slurm_adopt) without needing hackish
extra utilities to create and manage cluster-specific passphraseless
key pairs for every single user! :-)
There's a great cookbook online that tells you step-by-step how to set
it up:
https://en.wikibooks.org/wiki/OpenSSH/Cookbook/Host-based_Authentication
