I work for a webdevelopment company that also manages the hosting of our customers websites.The hosting is shared and only on 3 servers. The webservers are debian webservers where each customer has his own account to reach his own website files.
Normally I would login to the server as this customer and add my ssh key to an authorized_keys file so that I can simply ssh into the account without having to lookup the password, this works perfectly fine.
The downside is I have to do this for every account over again, is there a way to add it to the server only once so that I can access all the accounts?
I tried putting the authorized_keys file in a .ssh folder in the root of the server but this doesn't seem to provide me access with any account. I have to admit my linux knowledge is limited, so am wondering if this is even possible?
You can update your sshd_config and add to AuthorizedKeysFile also for example some path in /etc/ssh/authorized_keys where you can put your master key. This would authorize you with this key to all accounts. But don't forget to leave there also the original one:
[...]
AuthorizedKeysFile .ssh/authorized_keys /etc/ssh/authorized_keys
[...]
Or you can use certificates as described in ssh-keygen manual page. This would allow you to audit the access with these keys.
You can consider to use emcSSH tool for your purposes. This is blockchain-based distributed Public Key Infrastructure and group management system.
You can read details and download here: http://emercoin.com/EMCSSH
If needed any assistance, feel free for contact me. I'm author of this system, and can answer your questions.
Related
I read the question: How does the GitHub authentification work? and https://unix.stackexchange.com/questions/315615/is-ssh-public-key-associated-with-a-user Which is exactly what I am wondering. I am still missing a better answer.
When I test my SSH-key-pair I connect to user git#gitlab.com. My stored Public key has a fingerprint of base64. When the SSH Client(me) want to connect to the server(My gitlab/github account server) it sends its ID(fingerprint), the server checks it ".ssh/authorised_keys" and loops through the Fingerprints after the correct public key to encrypt the challenge.
On Github/Gitlab there are several thousand of users, they all use the same username ("git") to initiate a web (SaaS)session. So how is this separated on the server? I don't get root access on gitlab/github, of course. I only get access to my account though the generic user-session git#gitlab.com. But how is this implemented?
When I use SSH in other situations I have a specific username which I use to [my-username]#router.com
E.g.
If I would set up my own GitLab on a local NAS/Server. How can I create an account (User#local-gitlab.com) but the access rights are limited to the Fingerprint of the differents users SSH-key-pairs?
User: ID:001
User: ID:002
User: ID:003
Somehow I need to limit the access for ID:001 when he/she initiate a ssh-session with my server on account "User".
I can't speak for GitLab, but for GitHub, there is a dedicated service that terminates these connections, contacts the authentication service with the key in question, and then receives the response about whether the user is allowed to access that repo, and if so, contacts the servers storing the data.
GitHub has more than 65 million users, many users have multiple SSH keys, and there are also deploy keys for servers, so using the command directive with an OpenSSH authorized_keys file would be extremely slow, since it would involved parsing and reading probably gigabytes of data each time a connection was made.
If you need this yourself for a small set of users, the command directive in authorized_keys is a viable approach. If you need something more scalable, you can create a custom server with something like libssh and perform authentication yourself, either in that process, or in a separate process.
I found this question+answer: https://security.stackexchange.com/questions/34216/how-to-secure-ssh-such-that-multiple-users-can-log-in-to-one-account. Which highlights that you can put restrictions on authorised_keys. Don't know if that provides precise answer for my question, but it looks like it.
command="/usr/local/bin/restricted-app",from="192.0.2.0/24",no-agent-forwarding,no-port-forwarding,no-x11-forwarding ssh-rsa AAAA… git#gitlab.com
I guess there is several thousand of those lines at gitlabs/githubs servers in .ssh/authorized_keys where every single line points out access to only that gitlab/hub account.
Please comment if you don't agree.
I had an user account set up by my collegue weeks ago, to access our server(rhel). Now Im asked to copy my key so I can login to other servers in the cluster.
My first approach was to copy my /home/user/.ssh folder from the (already set-up) server to the new one. This one obviously fails, I found out with ls -a , that in my .ssh directory is only one file - known_hosts.
Im bit confused from my search results, is it necessary to create a new private-public key pair (I dont have any log about creating in before for the first server, so it was probably already setup for me), or is it sufficient to copy files from the first server and setup owners and permissions?
What you're probably looking for is file ~/.ssh/authorized_keys on the server. If you have your key set up, your public key should be stored there. If there is no such file, than you don't have your keys set up(do you have private keys files on your desktop?).
Please note that for usually ssh will require strict access permissions(rwx for user only) for your ~/.ssh directory and authorized_keys file.
Also you can use as many and as few keys as you wish, depending on your security needs. So using single key pair for multiple servers is possible.
I've been working with the server only for 2 days so I am sorry if that is simple question. I looked everywhere, but didn't find an answer.
So I have a Google compute engine account and I have owner privileges. When I run
gcloud compute ssh instance --zone us-central1-a
it works, but it creates a key with username that it takes from my computer account.
So when I am in google shell I can add or remove files using sudo. But when I go to Filezilla I have to use ssh file key and username from that key. And the only folder that accessible with that username is it's own folder. I am not sure what is the problem so I gave all the facts I could.
I'm not entirely sure I'm answering the right question, but I'll take a stab at it. The ssh keys created by/used by gcloud are specific to a particular linux user on your VM. As you note, you can use sudo when ssh'd in to edit files/directories owned by different users---the way this works is that you (roughly speaking) temporarily switch users to root when doing the file edit.
An scp client like Filezilla isn't going to be able to switch users that way. So you'll need a different technique to edit files with Filezilla.
I suggest ssh-ing in to your vm and using chmod or chown to change the ownership of files/directories that you want to use with Filezilla. Alternatively you could you use useradd -G to add you username to a group that can edit the files you care about.
Exactly what you'll do depends on the security policy you want to enforce for your files, but there a lots of decent options. The key test to run---can you get to a state where you can edit the files when logged in with SSH, but not using sudo? If so then you should be able to edit the files with Filezilla.
I couldn't find any basic info for designers (on a mac) for how SSH keys work - so thought I'd ask them here.
If I want to connect my work workstation to:
Github
A DEV server
A LIVE server
Do I generate one ssh key on the workstation and add it to all those servers or do I generate multiple keys - one for each server?
Once I've generated a key (or keys), do I copy it into the id_rsa file in my user account on that server (I realize I may have to create the id_rsa file)?
And if I now want to access the same server but from my home laptop, do I add the laptop's ssh key to the same id_rsa file on the server or do I create a new file?
If I need to create a new file, does it matter what the file is called - laptop_rsa?
I basically want to disable root login on my servers but I don't really understand how SSH applies to multiple machines and multiple servers.
Any help or pointers in the right direction would be much appreciated.
Cheers
You only need one key for the local machine that you are connecting
to all three servers.
For the DEV server and the LIVE server, you can add the contents of
your id_rsa.pub file to the
authorized_keys file on each of the target servers.
This file will be in the ~/.ssh directory. You will
need to create the file if it's not there (touch
~/.ssh/authorized_keys). Adding your public key to this file
will let you login with your passphrase rather than a password.
Place all authorized keys (i.e. your laptops id_rsa.pub) in the same
authorized_keys file on the target server.
Adding your keys to authorized_keys doesn't affect root login (that is a separate setting), however, it will prevent people from attempting to brute-force your password if you then turn off password login.
I guess I'm being a little hesitant but I deal with vcs's occasionally and always get asked for some sort of prompt, of course I'm attempting to access an external machine which I'm sshing into.
Basically my question is, say I don't have root access on this machine, would it still be possible to set this up? I've skimmed through reading it a couple times and I'm pretty sure I got the method down - you generate pub/private keys, sftp to the machine and throw your public into some authorized_keys directory. How is this managed with multiple users for example? Could the generic file name ( the .pub ) get overwritten, or am I completely misunderstanding the process here and it's setup to allow multiple keys natively?
If I'm not a sudoer and one of the server's directories needs to be chmod'd to say 700 whereas it's 655, I can't really do anything other than ask for su access, right?
If you have ssh access to the remote machine, you can generate the key pair on your local machine, add the public key to the authorized_users file on the remote machine, and then use this for authentication. You don't need root privileges to do this. The keys and authorized_files usually reside under your home directory ( myhome/.ssh/authorized_keys etc) so they don't get confused between users.
Your questions about setting directory permissions is unrelated, but if you own the directory or its parent (or its parent...) you will be able to set any permissions on the file in that directory.
Sounds to me like it might be time to curl up with a general *nix administration book, perhaps? Not light reading, but it can be useful and I always find it most informative to learn the details when I'm actually struggling with them.
I ssh all the time into a machine that allows su or sudo. But, it's set up not to allow ssh via "ssh root#machine". So to answer your question, yes it's possible.
You can only change the directory permissions if you own the directory or if you have root access.