Naming Public-Key on Server

Adirondacks · 10-12-2018, 11:51 AM

This is regarding setting up passwordless authentication for SSH.

Locally when I run ssh-keygen, I tend to use the naming convention: <company_initials>_id_rsa

For example:

abc_id_rsa
abc_id_rsa.pub

def_id_rsa
def_id_rsa.pub

My wanting to do this is to make key-pair for different servers more easily identifiable.

I have been told that it is okay to make such a change, and it has no impact on the internals of the public/private keys, but that I do need to specify the non-standard name when doing things like SSH'ing into my server.

For instance, I would need to specify this...

Code:

ssh -i ~/.ssh/abc_id_rsa user1@111.222.333.444 -p 22

So finally on to my question...

Being a newbie, I use cPanel to import my Public-Key onto my server.

In cPanel, under the heading "Import SSH Key", is a webform asking for...

- Choose a name for this key
- Paste the private key into the following text box
- Passphrase
- Paste the public key into the following text box

Questions:
1.) When I generated my key-pair, if I used the naming convention above, would I break things if in cPanel I named my Public-Key the default of "id_rsa.pub"?

2.) If I name the Public-Key "abc_id_rsa.pub" do I have to make any changes anywhere else, or will that work?

3.) Should I be including the ".pub" on the end, or is that implied for a Public-Key?

Thanks!

nodir · 10-12-2018, 12:42 PM

3) The *pub key is the one which gets put on the remote in the file ~/.ssh/authorized_keys, either copied manually or with ssh-copy-id (or similar command)

2) You don't have to make that change but for convenience you can create a file ~/.ssh/config

Code:

host abc
hostname abc.org
user username
port 22
#ServerAliveInternal 30
ServerAliveCountMax 100
IdentityFile ~/.ssh/abc_id_rsa

Now you can just use "host abc" (whichever you have choosen as a shortcut !)
ssh abc
rsync -auv ~/Downloads abc:Tmp/
git, sshfs, etc ... you will always be able to use the shortcut: "abc" which you have choosen for the user@hostname with the IdentityFile ...

Adirondacks · 10-12-2018, 01:00 PM

Quote:

Originally Posted by nodir

3) The *pub key is the one which gets put on the remote in the file ~/.ssh/authorized_keys, either copied manually or with ssh-copy-id (or similar command)

Right.

Quote:

Originally Posted by nodir

2) You don't have to make that change but for convenience you can create a file ~/.ssh/config

Code:

host abc
hostname abc.org
user username
port 22
#ServerAliveInternal 30
ServerAliveCountMax 100
IdentityFile ~/.ssh/abc_id_rsa

You lost me on how to create that file...

I am actually a Mac user. Could I create a file like that in BBEdit and then save it to: ~/.ssh/config

Is "config" the name of the file I would be creating?

Does that file already exist? (Don't want to overwrite anything!)

Quote:

Originally Posted by nodir

Now you can just use "host abc" (whichever you have choosen as a shortcut !)
ssh abc
rsync -auv ~/Downloads abc:Tmp/
git, sshfs, etc ... you will always be able to use the shortcut: "abc" which you have choosen for the user@hostname with the IdentityFile ...

I don't understand what to type?

What is rsynch?

Here is my original command I am used to running in Terminal...

Code:

ssh -i ~/.ssh/abc_id_rsa user1@111.222.333.444 -p 22

How would I modify that command after takin your advice?

nodir · 10-12-2018, 01:22 PM

On Linux and BSD systems:
"config" is the name of the file
"~/.ssh/config" is the path
if it exists, you don't overwrite, you append another entry.
Hence you then simply use, without -i :
ssh abc
ssh another_remote
ssh still_another_remote
So you just use whatver name you have choosen for your convinience as the first entry (name abc; the abc part).

Code:

host abc_convenient_name
hostname 111.222.333.444
user user1 
port 22 
ServerAliveCountMax 100
IdentityFile ~/.ssh/abc_id_rsa

Now you simply do:

Code:

ssh abc_convenient_name

(abc_convenient_name not being that convenient ... ).
rsync is just one example of a program based on ssh. All programs based on ssh will make use of ~/.ssh/config, so you will save yourself a lot of typing.

Turbocapitalist · 10-12-2018, 01:52 PM

I'd tweak that slightly, including indentation for readability.

Code:

Host 444 111.222.333.444
        HostName 111.222.333.444
        User user1 
        Port 22 
        IdentityFile ~/.ssh/abc_id_rsa
        IdentitiesOnly yes

Host *
        ServerAliveInterval 30
        ServerAliveCountMax 4

See "man ssh_config" for the details, but that would allow either

Code:

ssh 444

or

Code:

ssh 111.222.333.444

and the SSH client would fill in port, user, key file, etc. automatically.

Adirondacks · 10-12-2018, 02:47 PM

For now, I think I like the extra typing as it helps me learn the Linux command-line and better understand what I need to tell Linux/SSH to do.

But down the road that would be handy!

Thanks, @Nodir and @Turbocapitalist