SSH configuration: override the default username [closed]

Question

Is it possible to configure ssh to know what my username should be?

By default it uses the current username, which is not correct in my case.

I'm on a loaner laptop, and my username is loaner, but I want to tell ssh that my username is buck.

Bonus points: my username at home is bgolemon. If I could configure the username per-host that would be even better.

Madelenemadelin

Stack Overflow is a site for programming and development questions. This question appears to be off-topic because it is not about programming or development. See What topics can I ask about here in the Help Center. Perhaps Super User or Unix & Linux Stack Exchange would be a better place to ask. Also see Where do I post questions about Dev Ops? – Stroll

This is such a good question! – Abstruse

accepted answer here is better quality than superuser ones: includes global (default) user directive use and comments added make directive priorities clear – Gilbart

More about ssh config priorities, default and host-specific users and such: therootcompany.com/blog/ssh-defaults-config-and-priorities – Mulligatawny

Answer 1

Create a file called config inside ~/.ssh. Inside the file you can add:

Host *
    User buck

Or add

Host example
    HostName example.net
    User buck

The second example will set a username and is hostname specific, while the first example sets a username only. And when you use the second one you don't need to use ssh example.net; ssh example will be enough.

Ophthalmia

It's probably worth pointing out that according to man ssh_config: Since the first obtained value for each parameter is used, more host-specific declarations should be given near the beginning of the file, and general defaults at the end. So the Host * section should probably go at the end. – Stenson

It is worth noting that config file will be processed in top-to-bottom fashion, populating each field (User, HostName...) and skipping repeated fields if multiple Host directives are matched. If you define Host *, User jdoe at the top, and then define Host example, HostName abc.example.com, User root, attempting ssh example will be the same as if you entered ssh [email protected]. In order to define ssh defaults (ie. User root), Host * directive needs to be at the bottom of config file. – Corded

Also, don't forget chmod 600 on .ssh/config – Unusual

Note that if there are multiple hostnames that the server is accessible by (or if you want the same default username for multiple servers), you should change the first line to Host server1.local example.net *.example.org and just get rid of the HostName line. – Kristin

Answer 2

If you only want to ssh a few times, such as on a borrowed or shared computer, try:

ssh buck@hostname

or

ssh -l buck hostname

Permanganate

Thanks, but I'm already familiar with this. It seems redundant to specify buck@host when it's always buck@host. I'm trying to find a method to represent this information in a configuration file. – Madelenemadelin

Have you considered something as simple as alias sshhostname='ssh buck@hostname'? – Permanganate

Yes, I have. Learath2's answer is exactly what I was looking for. I can check this into my dotfiles repository and not worry about it ever again. – Madelenemadelin

I took the alias root because I connect to machines for different clients, where my username is different in each client environment. Another approach I suppose would be to have different local shell environments to set the ssh and related settings for each client. Or a VM per client. – Decolorant

Answer 3

If you have multiple references to a particular variable i.e. User or IdentityFile, the first entry in the ssh config file always takes precedence, if you want something specific then put it in first, anything generic put it at the bottom.

Disaccharide

This is exactly what I'm trying to figure out! Just move my Host * to the end of the file and everything works like I want. – Grissel

Answer 4

man ssh_config says

User

Specifies the user to log in as. This can be useful when a different user name is used on different machines. This saves the trouble of having to remember to give the user name on the command line.

Supermundane

"Identity" in this case is equivalent to the usual usage of "password". This is the data which authenticates you, but doesn't help specify who you are trying to authenticate as. – Madelenemadelin

Oops. There's a user setting in there as well. – Supermundane

Answer 5

There is a Ruby gem that interfaces your ssh configuration file which is called sshez.

All you have to do is sshez <alias> [email protected] -p <port-number>, and then you can connect using ssh <alias>. It is also useful since you can list your aliases using sshez list and can easily remove them using sshez remove alias.

Tetrastichous