Say I have local access to two machines A and B and remote access to machine C.

If I generate a public-private pair of keys for accessing machine C from A, can I share the private key with machine B to access machine C from it? Or do I need to generate a new public-private pair?

At the moment I have a pair of keys working to access C from A, but when I use this private key from B it doesn't work.

In case it matters, I use a config file for this as follows:

Host XXX
User XXX
HostName XXX
IdentityFile ZZZ

Where ZZZ points to the key in B (different paths in the machines A and B)

I am using the same username in both.


You always can. I think C will have your public key (outside) and, if A and B are both inside a local network (ie: your home network), you are not doing something risky by sharing, unless you use internet to send it unencrypted xD. If A and B are machines you own and you can be sure that nobody can read your private key, then you can share a private key with no risk.

The thing is that your private key must never be compromissed. Ensure you have a revoke certificate generated and printed, and the public key in a keyserver, so anyone can just refresh it to see new signatures and revoke certificates.

I will give you an example. I have a GitHub account, and I access it from SSH from my machines at home. I have more than one machine, and more than one OS inside each machine, but I use only one key for GitHub. Why? Well... I have my key in personal, encrpted drives. Nobody can see my private key, no matter how much copies I own.

Hope it'ill be helpful Cheers

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Regardless the user name you use, you can copy the private key from A to B without any problem. It works and there is IMHO no problem with that.

I also do it this way. For security reasons you should ensure that every private keys is protected with a passphrase.

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  • I think that depends on the interpretation of "user". Is it the OS user? is it the remote OS user? is it the User ID of the GPG/PGP key? – D4RIO Jan 13 '12 at 19:56
  • I only referenced to the user name that points the user's OS user name. You can also use different GPG keys to access C... – tuergeist Jan 15 '12 at 18:13

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