I use dsa key with passphrase to login via ssh into CentOS 6 remote server. Unfortunately I forgot the passphrase.
Is there a way to reset or retrieve passsphrase?
I still do have access to root of remote server through webmin.
no, the keyfile itself does not hold any data that would aid you in breaking/recovering (quite the same) the encryption. if you did not back up the information otherwise, you cannot recover it.
you however simply install a new key.
Related
Currently there is this web in an apache server with SSL key with passphrase, so when the server restart you must manually unlock the key by entering the passphrase.
I know I could recreate the key without passphrase.
I also know I could use SSLPassPhraseDialog and auto-unlock the key with a script.
But doesn't seems right to me to protect the key with a passphrase, if this is going to be written down in a clear text file. Event though this file is root 000 file permissions.
What I'm I missing? Should I just remove the passphrase and focus on perimetral defense and other security methods?
I feel must be a third choice, the good one, that I'm not aware of.
What are the best choice to protect a certificate key on the apache server?
Thank you
I have created a ssh key for my droplet at digital oceans. After few days I have deleted the key from security page and still I am able to ssh using putty with that key. Is it necessary to delete the key from authorized_keys file. If so, then what is the use of adding/deleting ssh keys to droplet on their above mentioned security page?
Question at digital ocean - https://www.digitalocean.com/community/questions/how-to-remove-ssh-keys-for-the-droplet
As the digital tutorial page says
"You can create new DigitalOcean droplets with an SSH key already set up on them by adding your computer’s SSH key to the control panel.".
To setup a ssh key for the droplet it is needed to add your newly created key to the droplet's control panel.
You are able to access the droplet even after you deleted the ssh from security page because now the ssh also resides inside your droplet's ~/.ssh/ folder(remote machine).
To authenticate using SSH keys, a user must have an SSH key pair on their local computer. On the remote server, the public key must be copied to a file within the user's home directory at ~/.ssh/authorized_keys. This file contains a list of public keys, one-per-line, that are authorized to log into this account.
When a client connects to the host, wishing to use SSH key authentication, it will inform the server of this intent and will tell the server which public key to use. The server then check its authorized_keys file for the public key, generate a random string and encrypts it using the public key.
So, it necessary to delete the key from authorized_keys file to stop ssh access to the remote machine.
After the droplet creation security page lists the keys just to show what all ssh keys you used for all your droplets.Deleting them from security page will not prohibit you from accessing your droplet.
When trying to connect via PuTTY with SSH, I get the following warning:
The server's host key is not cached in the registry. You have no
guarantee that the server is the computer you think it is. The
server's rsa2 key fingerprint is: ssh-rsa 1024
cc:2v:25:73:c8:a6:59:7e:b8:23:2d:13:3e:66:9b:b9 If you trust this
host, enter "y" to add the key to PuTTY's cache and carry on
connecting. If you want to carry on connecting just once, without
adding the key to the cache, enter "n". If you do not trust this host,
press Return to abandon the connection. Store key in cache? (y/n)
Connection abandoned.
The issue is, the fingerprint shown in the warning message is not the fingerprint to the key that I want to use. How do I change it?
The issue is, the fingerprint shown in the warning message is not the fingerprint to the key that I want to use. How do I change it?
That should not be. That is fingerprint of the key that belongs to the server you are connecting to.
I have heard that SSH does not need certificates.
But for RSA authentication of SSH , it should make sure that public key belong to the server and it can be done with certificates.
But it does not use certificates.
So how does it do?
No. It does NOT NEED them, but it CAN use them (but they are different then the certificates used in SSL! for various reasons). Certificates help only to delegate the verification to some certificate authority. To verify the public key, you just need to get the public key using "secure" channel.
So how you can verify the public key of the server you are connecting to?
There are several possibilities. The server admin will send you using different secure channel the public key of fingerprint of the public key. They can look like this:
Public key: ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAubiN81eDcafrgMeLzaFPsw2kNvEcqTKl/VqLat/MaB33pZy0y3rJZtnqwR2qOOvbwKZYKiEO1O6VqNEBxKvJJelCq0dTXWT5pbO2gDXC6h6QDXCaHo6pOHGPUy+YBaGQRGuSusMEASYiWunYN0vCAI8QaXnWMXNMdFP3jHAJH0eDsoiGnLPBlBp4TNm6rYI74nMzgz3B9IikW4WVK+dc8KZJZWYjAuORU3jc1c/NPskD2ASinf8v3xnfXeukU0sJ5N6m5E8VLjObPEO+mN2t/FZTMZLiFqPWc/ALSqnMnnhwrNi2rbfg/rd/IpL8Le3pSBne8+seeFVBoGqzHM9yXw==
You can store this one directly in your ~/.ssh/known_hosts prefixed with the server name and space.
Fingerprint SHA256:zzXQOXSRBEiUtuE8AikJYKwbHaxvSc0ojez9YXaGp1A bitbucket.org (RSA)
When you connect to the server for the first time, you are asked similar question:
The authenticity of host 'bitbucket.org (104.192.143.3)' can't be established.
RSA key fingerprint is SHA256:zzXQOXSRBEiUtuE8AikJYKwbHaxvSc0ojez9YXaGp1A.
Are you sure you want to continue connecting (yes/no)?
Then it is your responsibility to verify that the fingerprint is the same as the one you got from your admin.
If you don't do that, you are in danger that somebody redirected your connection to some malicious server and you are connecting somewhere completely else. The host keys are unique and this attacker would have different key (and therefore different fingerprint) unless he already compromised the original server (and then you are screwed already).
There is also possibility to add the host keys to the SSHFP DNS record, which will eliminate the burden above (you should have DNSSEC, otherwise the DNS records can be modified the same way as your direct connection). For this to work, you need to turn it on in your ssh_config using VerifyHostKeyDNS options.
And what about the certificates?
SSH can use certificates. This is common in company environment, where you are already given a known_hosts file configured with the certificate authority, which is used to sign all the host keys (and usually also the clients authentication keys). In that case, you don't need anything from above and connecting to local infrastructure "just works". Note, these certificates are not X509 as used in SSL/TLS PKI. For more info about these certificates, see manual page for ssh-keygen, which explains that in detail.
I want to access to a server (hosted in Lonex) trough SSH (for file handling). For this I use PuTTY. To do so safely, I use Pagent, it needs a public and a private key.
In the server, under the ssh folder in the root directory there are two files:
id_rsa - which has the private key.
id_rsa.pub - which has a public key.
Given this information, if posible, I would like to generate the necessary files for Pagent.
What I have tried:
Using PuTTYgen to import/load a local copy of the file id_rsa. This successfully generated the the .ppk file needed for Pagent. I referred to the .ppk file in connection -> ssh -> auth. In this .ppk file appears the public and the private key. But when I use PuTTY to connect, having the generated .ppk added to Pagent, an alert prompts stating that I do not have the server's host key cached in the registry and then shows the server's rsa key fingerprint, which I know to not be the right one from the one shown in Pagent. The fact that this alert prompts tells me that my Pagrent key is not correct. Am I correct?
Comments:
- Given that the host already has a public/private key pair I believe I should generate a local private key given the same public key from the host. I could not accomplished this (I read about ssh-keygen commands but I did not find out how to get what I wanted done).
- The ISP suggested that everything I need is in this link: http://sourceforge.net/apps/trac/sourceforge/wiki/SSH%20keys#KeyGeneration:PuTTY
I could not find the use to it given that I do not have a form where I should place a public key generated locally by me and also the fact that it does not consider the situation where I already have a public key generated in the host.
- I asked the ISP if it was possible to add a public key generated locally by me to the authorized_keys2 file and they told me no due to the fact that it is a shared hosting.
Your question really boils down to this:
The fact that this alert prompts tells me that my Pagrent key is not
correct. Am I correct?
No; this is not correct. Your agent (Pageant) is likely set up correctly. As you said,
an alert prompts stating that I do not have the server's host key
cached in the registry and then shows the server's rsa key
fingerprint,
That prompt is for the server's host key, not your user's private key. Pageant only caches your user's private key, not the host's public key (or public key fingerprint). Pageant's purpose is to hold your private key so that the server can identify you; the purpose of the prompt that you saw was for PuTTY to allow you to verify that the server that you're connecting to is really the server you meant to connect to (i.e. that you're not connecting to an attacker's machine).