I have too many machines floating around, some virtual, some physical, and they’re getting added and removed semi-frequently as I play around with different tools/try out ideas. One recurring pain point is I have no easy way to manage SSH keys around them, and it’s a pain to deal with adding/removing/cycling keys. I know I can use AuthorizedKeysCommand on sshd_config to make the system fetch a remote key for validation, I know I could theoretically publish my pub key to github or alike, but I’m wondering if there’s something more flexible/powerful where I can manage multiple users (essentially roles) such that each machine can be assigned a role and automatically allow access accordingly?
I’ve seen Keyper before, but the container haven’t been updated for years, and the support discord owner actively kicks everyone from the server, even after asking questions.
Is there any other solution out there that would streamline this process a bit?
Are you initiating SSH connections from all these hosts?
If you just need to SSH to these hosts, use a single key and copy the public key only to the hosts you need to connect to. If you don’t want to copy the pubkeys to target hosts, use LDAP + SSSD or certificates.
Then, if you do need to initiate connections from these hosts and use an SSH agent you can forward your agent and SSH to another host
client> ssh -A host1
host1> ssh host2
host2>
client> ssh -A host1
host1> ssh -A host2
host2> ssh -A host3
host3>
Have an alias so trusted hosts can bounce through my authorization host and end up on a tmux session on the targetted host. It has logging and such but mostly it’s for simplicity.
If I plan to use that connection a lot there’s a script to cat my priv key through the relay.
Have an scp alias too, but that gets more complicated.
For more sensitive systems I have 2fa from gauth set up, works great.
This is a common pattern, typically called a “jump host” or “bastion host”.
a script to cat my priv key through the relay
When it comes to security, I typically recommend against rolling your own. SSH already has agent forwarding option to do this securely and the -J option to accomplish the same without even needing to forward the key. The agent can seem complex at first, it’s actually pretty simple and worth learning.
Feel free to message me if you have more questions, I’ve got lots of experience w/ SSH.
I did not know -J, I rolled my own because I’ve been doing it forever and many of my tricks (non-ssh included) aren’t as easily portable across different os’s.
For some reason ssh-copy-id has been failing for me sometimes lately because it can’t reach the agent, while cat always works, but I never learned much about the user agent, let me look into that now, thanks for the tip!
I think -J is newer and may not work if you have distro versions older than like 5 years (eg. Centos 7 or before). There is a less convenient syntax that does the same thing though
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Are you initiating SSH connections from all these hosts?
If you just need to SSH to these hosts, use a single key and copy the public key only to the hosts you need to connect to. If you don’t want to copy the pubkeys to target hosts, use LDAP + SSSD or certificates.
Then, if you do need to initiate connections from these hosts and use an SSH agent you can forward your agent and SSH to another host
Have an alias so trusted hosts can bounce through my authorization host and end up on a tmux session on the targetted host. It has logging and such but mostly it’s for simplicity.
If I plan to use that connection a lot there’s a script to cat my priv key through the relay.
Have an scp alias too, but that gets more complicated.
For more sensitive systems I have 2fa from gauth set up, works great.
This is a common pattern, typically called a “jump host” or “bastion host”.
When it comes to security, I typically recommend against rolling your own. SSH already has agent forwarding option to do this securely and the -J option to accomplish the same without even needing to forward the key. The agent can seem complex at first, it’s actually pretty simple and worth learning.
Feel free to message me if you have more questions, I’ve got lots of experience w/ SSH.
I did not know -J, I rolled my own because I’ve been doing it forever and many of my tricks (non-ssh included) aren’t as easily portable across different os’s.
For some reason ssh-copy-id has been failing for me sometimes lately because it can’t reach the agent, while cat always works, but I never learned much about the user agent, let me look into that now, thanks for the tip!
I think -J is newer and may not work if you have distro versions older than like 5 years (eg. Centos 7 or before). There is a less convenient syntax that does the same thing though
$ ssh -o ProxyCommand="ssh -W %h:%p bastion-host" remote-hostSee: https://www.redhat.com/sysadmin/ssh-proxy-bastion-proxyjump