linux - How to make ssh log in as the right user?

I use ssh on a variety of machines, mainly linux. Accounts on these machines vary in naming scheme: if my name is First Last, then I have accounts: first, flast, last_f, lastf, and sometimes I need to log in as root. For each machine I use, I would like the openssh client to know which account to use when I don't specify on the command line.

So the question is: How do I make ssh server Do The Right Thing when a username is not specified?

Answer

You can create a config file in your home .ssh directory, which can specify a default user, identity file etc and assign it to an alias which you can use to connect.

For example, you could put this into the ~/.ssh/config file:

Host example
    HostName example.com
    User first_last
    IdentityFile ~/.ssh/example_rsa
    Port 22
    RSAAuthentication yes
    PubkeyAuthentication yes

Host example2
    HostName example2.com
    User last_first
    # other parameters as needed

Then you can just type ssh example or ssh example2 on the command line to connect.

So you can set one up for each machine you want to connect to, with the relevant user. Then just use the aliases to connect without having to specify a user. You can also use a pattern to match multiple hosts.

There's more information, and details of what you can specify in a config file in the ssh_config man page.

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