SSH, or secure shell, is the most common way of connecting to Linux hosts for remote administration. Although the basics of connecting to a single host are often rather straight forward, this can become unwieldy and a much more complicated task when you begin working with a large number of remote systems.

Fortunately, OpenSSH allows you to provide customized client-side connection options. These can be saved to a configuration file that can be used to define per-host values. This can help keep the different connection options you use for each host separated and organized, and can keep you from having to provide extensive options on the command line whenever you need to connect.

In this guide, we'll cover the basics of the SSH client configuration file, and go over some common options.

1. Generate SSH key:

   $ ssh-keygen -t rsa -C <email1@example.com>

2. Generate another SSH key:

   $ ssh-keygen -t rsa -f ~/.ssh/accountB -C <email2@example.com>

   Now, two public keys (id_rsa.pub, accountB.pub) should be exists in the ~/.ssh/ directory.

   $ ls -l ~/.ssh     # see the files of '~/.ssh/' directory 

3. Create config file ~/.ssh/config with the following contents:

   $ nano ~/.ssh/config
   
   Host bitbucket.org  
       User git  
       Hostname bitbucket.org
       PreferredAuthentications publickey  
       IdentityFile ~/.ssh/id_rsa  
   
   Host bitbucket-accountB  
       User git  
       Hostname bitbucket.org  
       PreferredAuthentications publickey  
       IdentitiesOnly yes  
       IdentityFile ~/.ssh/accountB  

4. Clone from default account.

   $ git clone git@bitbucket.org:username/project.git

5. Clone from accountB account.

   $ git clone git@bitbucket-accountB:username/project.git

See More Here

scp allows files to be copied to, from, or between different hosts. It uses ssh for data transfer and provides the same authentication and same level of security as ssh.